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Fluorescence can be used to measure and visualize the activity of herbicides that inhibit the photosynthesis. Glyphosate, although not acting primarily on the photosystems, appears to increase fluorescence of plants. We investigated whether fluorescence technology is a useful tool to both quantify and image of the performance of different adjuvants for glyphosate. A red laser beam providing equipment is used to scan black nightshade plants at a low and high light intensity. A cooled, integrating 16 bit CCD camera is used to record the fluorescence during the low level (Fo) and high level scan (Fm). The relative increase of fluorescence expressed as [(Fm—Fo)/Fm] 100 % is calculated and color images are produced. Glyphosate was applied at two suboptimal application rates of 16.9 and 33.8 g ae/ha at 200 L/ha. Both the influence of glyphosate rate and the influence of added adjuvants were obvious. The fluorescence data 30 h after treatment demonstrated that the adjuvants HM9121-A and HM9110 performed better than AMS, HM9541-A, HM9910, or HM2005-B. This observation was consistent over the next three observations (54, 78, and 102 h). The fluorescence data after 72 h correlated (R2=0.82; logarithmic regression) with the fresh weight reduction caused by the glyphosate treatments. The adjuvants HM 9121-A and HM9110 performed the best and the adjuvant HM9541-A had little effect on glyphosate performance. Both imaging and fresh weight data indicate that HM 9121-A performs somewhat better than HM9110.

There is a wealth of information in the published literature which describes a multitude of approaches to enriching the environment of laboratory animals. This paper attempts to review the various methods of enrichment through social contact, enhancement of the environment and diet, and improvements in husbandry. It attempts to place the various enrichment initiatives within the context of a laboratory which conducts regulatory toxicology, describes some of the experiences in the author's own laboratory and attempts to highlight those ideas which might prove practical to implement in the future. The aim is to demonstrate that a creative approach to environmental enrichment is indeed compatible with regulatory toxicology. It is hoped that this will encourage those responsible for the care and welfare of animals in such a laboratory to challenge historical practices and include environmental enrichment as a fundamental necessity of study design.

The strength of autoclaved lightweight concrete (ALC) is evidently lower than that of normal concrete. Therefore, when movement occurs at a sealed joint between ALC panels, the sealant is required to deform and remain intact without damaging the ALC substrate. However, there is currently not sufficient information to permit evaluation of the expected performance of sealants applied to ALC substrates. In this study, static and dynamic tests were carried out in order to obtain an index that could be used to select the modulus of a sealant that can be expected to provide long-term performance when applied to an ALC substrate. To develop this index, an initial study was carried out in order to clarify actual joint movement between ALC panels of buildings; the expansion and contraction at the joint were measured, and shear joint movement was calculated based on the expected story-to-story drift of an external wall due to earthquake loads. Thereafter, in a subsequent stage of the study, five types of two-component polyurethane sealant products, of different elastic modulus, were subjected to tensile and shear tests from which the relationship between stress and the type of joint fracture was determined. The results from these tests revealed that when the stress is greater than 0.6 to 0.7 N/mm2, the ALC substrate is more easily fractured than the sealant. In a final stage of the study, the cyclic fatigue resistance of the same two-component sealants was evaluated using tensile and shear fatigue tests. Results from the fatigue tests indicated that the high modulus sealants lost adhesion from the ALC substrate at an early stage in the test. As well, the fatigue resistance of test specimens with joints having three-sided adhesion was lower than that of specimens having normally configured joints with adhesion on two sides of the sealant. Therefore, on the basis of results derived from all the studies, it was determined that a suitable sealant for use on ALC substrates is a sealant having a low modulus that is applied in the normal fashion as a two-sided joint. Copyright © 2012 by ASTM International., 4th Durability of Building and Construction Sealants and Adhesives, 16 June 2011 through 17 June 2011, Anaheim, CA

Adhesive Applied Roofing System (AARS)s are regaining popularity in the Canadian low slope application. AARSs use no fasteners. All components (e.g., steel deck, vapour barrier (if any), insulation board, cover board, base sheet, and cap sheet) are integrated using cold adhesives and presented as a new generation of Built-Up Roofs. As there are no metal fasteners, AARSs can offer an advantage of a reduction in the moisture migration and thermal bridges of the roof assemblies. Moisture in the roof envelope can lead generally to material deterioration, structural integrity problems, and the growth of mould. Even though AARSs have been in use, existing uplift standards do not certify them for wind uplift performances. A new project, the “Development of Wind Uplift Standard for Adhesive Applied Low Slope Roofing System,” has been initiated in collaboration with industries, universities, and government departments. The project has three major tasks: Experimental investigation, formulation of a numerical model, and development of wind design guide and standards. This paper documents a segment of the findings from this project. Under Task 1, investigations were completed by constructing over 600 specimens constructed using cold adhesives and examining the peel resistance of bonded roofing components through mechanical separation of bonded layers by applying shear forces. These specimens use the insulation and the cover board components exclusively because they are more vulnerable to peeling under shear forces. Based on this scrutiny, three key parameters; namely, peel position, peel angle, and specimen size were optimized. This paper presents the findings and development of a standardized test method to determine the peel resistance of AARS specimens.

In the present paper, generalized Paris and Wohler equations are derived according to dimensional analysis and incomplete similarity concepts. They provide a rational interpretation to a majority of empirical power-law criteria used in fatigue. In particular, they are able to model the effects of the grain size, of the initial crack length, as well as of the size-scale of the tested specimen on the crack growth rate and on the fatigue life. Regarding the important issue of crack-size dependencies of the Paris’ coefficient C and of the fatigue threshold, an independent approach, based on the application of fractal geometry concepts, is proposed to model such an anomalous behavior. As a straightforward consequence of the fractality of the crack surfaces, the fractal approach provides scaling laws fully consistent with those determined from dimensional analysis arguments. The proposed scaling laws are applied to relevant experimental data related to the crack-size and to the structural-size dependencies of the fatigue parameters in metals and in quasi-brittle materials. Finally, paying attention to the limit points defining the range of validity of the classical Wohler and Paris power-law relationships, correlations between the so-called cyclic or fatigue properties are proposed, giving a rational explanation to the experimental trends observed in the material property charts.

Oxygen distribution in the rod cladding tubes during a Loss of Coolant Accident (LOCA) situation is known to play a key role regarding the post-quench mechanical properties of fuel rods. Analyticalsolutions of the diffusion equations in the complex multilayer and multiphase systems describing thecladding material tube during high temperature oxidation are limited to stationary isothermal conditions. To address the problem of non-stationary transient LOCA situations, a numerical tool (named DIFFOX) hasbeen developed. In the first part, the main assumptions and main features of the code are described. In parallel to the code development, an experimental program has been launched to provide a validation database as well as to input data for improvement of the code models. Zircaloy-4 cladding samples have been pre-oxidized at low temperature then vacuum annealed or steam oxidized at high temperature. Oxygen distribution profiles are investigated by Electron Probe Microanalysis. The ability of the code to describe the chemical reduction of the pre-oxide layer and oxygen diffusion into the metal during high temperature annealing is demonstrated. Regarding high temperature steam oxidation, the pre-oxide layers are observed to be either protective or not on a same given sample. While a good code to experimental data agreement is obtained in the first case, the growing of a high temperature oxide underneath the pre-oxide is not well reproduced by the code. The effect of hydrogen has also been investigated by performing small scale oxidation tests on 600 wppm hydrogen charged Zy-4 cladding. Samples have been long-term annealed for homogenization after oxidation. The main purpose of these experiments is to provide quantitative data on the modification of the α/α+β and α+β/β transus of the Zy4-O pseudo binary phase diagram induced by the presence of hydrogen. A variation of the transus locations deduced from these experiments is proposed. Copyright © 2011 by ASTM International.

The highly hardened surface layers obtained from a TiN-physical vapor deposition (PVD) coating and a treatment that leads to a surface carbon enrichment, applied to American Iron and Steel Institute (AISI) 304, 316, and 316L stainless steels, have been characterized. The metallographic analyses have revealed a depth of about 2.5 μm for the TiN-PVD treatment (1150 HV) and of between 30 and 40 μm for the carbon enrichment (1000–1150 HV), depending on the steel composition. The molybdenum enhancing carbon diffusion is also discussed. The X-ray diffraction analysis has shown an increase in the lattice parameter, subsequent to insertion of the carbon interstitial element, a reduced Fe5C2 Hagg carbide precipitation (mainly on AISI 304 samples), and high compressive stresses. The carbon profiles, obtained on carbon enriched samples through microprobe analysis, have been related to the HV profiles.

This paper reviews existing specifications, specifically for the application of crushed concrete or recycled concrete aggregate (RCA) as pavement material for unbound subbases and base courses. While the use of recycled crushed concrete is not new internationally, its application in Australia is unique as it is being commonly used as a granular basecourse/subbase supporting thin bituminous seals (asphalt or spray seal/chip seal). Commonality of specifications is explored and differences that exist are questioned. In light of practice outside of Australia, limitations by Australian authorities placed on recycled material inclusions other than crushed concrete are raised. In this paper, two South Australian-based RCA products, which were designed for use as pavement bases, are compared with current engineering specifications. The RCA products performed well in terms of resilient modulus and permanent deformation. However, properties such as abrasion resistance and wet/dry strength may restrict the application of the material if current specifications are justifiable. Refereed/Peer-reviewed

Stainless steels are widely used in chemical and other industries due to their corrosion resistance. However, because of their low hardness and wear properties, their applications are limited. Many attempts have been made to increase the surface hardness of these materials by using plasma techniques. Plasma nitriding is distinguished by its effectiveness, and for presenting a relatively low cost and being a clean process, producing hard surface layers on stainless steels. Aiming to verify the influence of the temperature and pressure on the modified resultant layers, samples of AISI 316 and 409 stainless steels were plasma nitrided in two different temperatures (450 and 500°C) and pressures of 400, 500, and 600 Pa for 5 h. After the nitriding treatment, the layers were analyzed by means of optical microscopy and wear tests. Wear tests were conducted in a fixed-ball micro-wear machine without lubrication. After the plasma nitriding treatment on AISI 316 and 409 samples, homogeneous and continuous layers were produced and their thicknesses increased as the temperature increased and as the pressure decreased. The nitriding treatment on the AISI 316 steel resulted on the formation of expanded austenite layers at 450°C and chromium nitrides (CrN and Cr2N) phases at 500°C. The nitriding treatment on AISI 409 yielded the formation of similar layers for both treatment temperatures; these layers constituted mainly chromium (Cr2N) and iron (Fe2N, Fe3N, and Fe4N) nitrides. After the nitriding treatment, the AISI 316 steel sample presented higher wear resistance for lower temperature and pressure values. The increase on layer fragility, for higher temperature and pressure values, can be responsible for this inverse tendency. The wear resistance of the nitrided AISI 409 sample followed a logic tendency: the harder the layer, the better the performance, i.e., the performance was improved with the increase in both the temperature and pressure.

This paper investigates the role of the vapor barrier in exterior wood-frame stucco walls with the help of a two-dimensional hygrothermal simulation tool, hygIRC-2D. For this purpose, the wall is subjected to the exterior weather conditions of six different North American geographic locations and three different interior climatic conditions. Seven different vapor diffusion strategies, generated by varying the water vapor permeance of the vapor barrier, installed outboard of the interior finish, have been studied to generate critical understanding on the role of vapor barrier in the wood-frame stucco walls. The outputs from the simulations have been analyzed with the help of a novel moisture response indicator called RHT index. Simulation results indicate that the vapor transmission characteristics of the vapor barrier, in terms of water vapor permeance, play a very important role in the overall moisture response of the wood-frame stucco wall. A very high or low vapor permeance of the vapor barrier does not produce the optimum moisture management strategy for the wood-frame stucco wall. Moreover, simulation results indicate that the removal of vapor barrier from the wall system can result in a heightened moisture response and a considerable accumulation of moisture in the interior gypsum board that may lead to severe consequences in particular, the premature deterioration of the interior facing gypsum board. It has also been observed from the simulation outputs that the optimum vapor diffusion strategy, that of limiting the vapor permeance of the vapor barrier, is not a function of interior climatic conditions considered in this study. It is hoped that the results reported in this paper will shed some light on a number of concerns raised in recent years on the role of vapor barrier in wood-frame stucco wall construction.

The ability of a wall assembly to manage rainwater and control rain penetration depends on the assembly configuration, including interface details for penetrations, and on the rain loads to which the wall is subjected. There are a variety different protocols for evaluating the ability wall systems to resist water intrusion. Generally they involve spraying varying amounts of water while maintaining a pressure difference across the specimen. Across the conterminous United States hourly weather data for extended periods (climatic data) is available for many locations. From this climatic data estimates of wind-driven rain loads can be determined. We answer the question of how often these combinations of rainfall intensities and pressure are likely to present a problem with respect to moisture management of the assembly and how often these are likely to occur over the expected life of the wall assembly. Climate information related to rainfall and wind-driven rain for Boston, Miami, Minneapolis, Philadelphia, and Seattle are provided. A methodology for generating rates of water spray impinging on and pressure differences acting across the wall assembly is also developed. Although the methodology was primarily developed to select the proper testing criteria and test conditions to mimic real events, it can also be used by designers and practitioners to: (i) determine the response of the wall assembly to the effects of wind-driven rain; (ii) estimate design loads below which adverse effects on the assembly are minimized; (iii) assess the likelihood and degree of damage to the assembly when design loads are exceeded; (iv) estimate the long-term performance of the wall assembly based on watertightness and moisture management the wall assembly.

[EN] The main difficulty for the application of Rp on site is the vanishing of the current with the distance which has been overcome with the use of a modulated confinement of the current only feasible if the guard ring is monitored during the measurement by means of electrodes able to detect the distance reached by the current. In the present paper after a short review of existing corrosion rate meters to measure on site, results of a comparison made of reinforced concrete slabs with various degradations such as carbonation or chloride among several using a guard ring with modulated confinement of the current is presented in order to have a reproducibility and repeatability for the measurements. Results show a good correlation among all the methods used for the corrosion rate evaluation.

16th International Symposium on Zirconium in the Nuclear Industry, 9th May 2010 – 13th May 2010, Chengdu, Sichuan Province, China; International audience; Zirconium alloys are commonly used in Pressurized Water Reactor as fuel rod cladding tubes. After irradiation and cooling in pool, the Spent Nuclear Fuel Assemblies are either transported for wet storage to a devoted site or loaded in suitable casks for dry storage on Nuclear Power Plant site. During dry transportation or at the beginning of dry storage, at temperatures around 400°C, the cladding experiences a creep deformation under the hoop stress induced by the internal pressure of the fuel rod. During creep a recovery of the radiation damage can occur that can affect the subsequent mechanical properties. The mechanical behavior of the cladding has been investigated in laboratory on two neutron irradiated cladding materials: fully recrystallized Zr-1%Nb and stress relieved Zircaloy-4. Creep tests under internal pressure were conducted at 400°C and 420°C. After depressurization and cooling, ring tensile tests were carried out at room temperature. In addition, Transmission Electron Microscopy observations have been performed after testing. The post-creep mechanical response exhibited a decrease of the strength compared to the asirradiated material. This decrease is associated with a significant recovery of the ductility, which becomes close to the ductility of the unirradiated material. The Transmission Electron Microscopy examinations, especially conducted on recrystallized Zr-1%Nb ring samples, revealed that the radiation defects have been annealed. It was also observed that, as for the unirradiated material, the deformation occurred homogeneously throughout the grains. No dislocation channel was indeed observed contrary to the as-irradiated material. These observations explain the recovery of the strength and of the ductility after post-irradiation creep that may occur during dry transportation or at the beginning of dry storage.

A quench probe, based on the Temperature Gradient method was used to measure and record cooling curves when quenching real axially symmetric workpieces of any complex shape in liquid quenchants. Calculation of relevant heat transfer coefficients is based on the cooling curve measured just below surface of the cylindrical probe of 50-mm diameter. A two-dimensional computer program, based on the cooling time from 800°C to 500°C (t8/5), and the Jominy hardenability curve of the steel grade in question, is used to predict the hardness distribution within the whole volume of the workpiece, all at once, which is a unique feature of this method.

A volumetric pressure plate (extractor) can be used to measure the soil-water characteristic curve in the laboratory using the axis translation technique. The volume of extracted water from the soil specimen in the volumetric pressure plate can be continuously measured during the test without the stoppage of air pressure during the measurements. However, the water volume measurement in the volumetric pressure plate requires an air trap, a ballast tube, a burette, and a vacuum device while maintaining a constant pore-water pressure in the soil specimen, which is quite complicated and tedious. In order to improve the measuring method of the volumetric pressure plate, a modified volumetric pressure plate was developed and tested on residual soil specimens. The modified apparatus can measure the volume of the extracted water using both Method A and Method B of ASTM D6836-02 depending on the range of matric suction. In addition, the volume of diffused air during testing can also be measured for correcting the water volume change measurements. The improvements of the modified apparatus and typical results obtained from the tests are discussed in the paper. Accepted version

The engineering and economical aspects of the optimization of steel shaft quenching and tempering were investigated. The mathematical model and method of computer simulation for the prediction of fatigue properties of quenched and tempered steel were developed. Computer simulation of the fatigue properties of quenched and tempered steel was applied in the optimization of quenching and tempering of steel shafts. The proper heat treatment process was accepted based on economical analysis. Fatigue properties of quenched and tempered steel were predicted based on microstructure composition and yield strength. Microstructure composition and yield strength were predicted based on as-quenched hardness. The distribution of as-quenched hardness in the workpiece was predicted through computer simulation of steel quenching using a finite volume method. The as- quenched hardness was estimated based on time of cooling and on Jominy test results. It was taken into account that the mechanical properties of quenched steel directly depend on the hardness, degree of hardening, and microstructural constituents. Using a numerical simulation of microstructure and mechanical properties, it was found out that the investigated shaft has the best fatigue properties in cases when the shaft was machined or formed on proper geometry before proper quenching and tempering. Through economical analysis of the investigated shaft manufacturing, it was found out that the most suitable shaft manufacture process is to manufacture the shaft from the quenched and tempered bar. But in this case, heterogeneous microstructures of ferrite, perlite, bainite, and martensite with very low fatigue limits could appear at some critical locations.

Promoted ignition testing [1–3] is used to determine the relative flammability of metal rods in oxygen-enriched atmospheres. In these tests, a promoter is used to ignite each metal rod to start the sample burning. Experiments were performed to better understand the promoted ignition test by obtaining insight into the effect a burning promoter has on the preheating of a test sample. Test samples of several metallic materials were prepared and coupled to fast-responding thermocouples along their length. Various ignition promoters were used to ignite the test samples. The thermocouple measurements and test video were synchronized to determine temperature increase with respect to time and length along each test sample. A recommended length of test sample that must be consumed to be considered a flammable material was determined based on the preheated zone measured from these tests. This length was determined to be 30 mm (1.18 in.). Validation of this length and its rationale are presented.

Laboratory water spray testing identifies the performance of a component or assembly under a specified set of simulated wind-driven rain conditions. Well-developed water spray test protocols can also help identify where an assembly is vulnerable to water entry, the test loads at which water entry occurs, and whether the water entry is managed by the installation details in such a way that it does not result in within-wall damage. This paper presents a proposed laboratory test protocol for assessing the effectiveness of wall-window interface details with regard to management of rainwater and provides a rationale for a performance-based approach to the evaluation method. An overview of the test approach is provided, and details of the test apparatus and test specimen are given, including information on implementation of the test method. Examples of testing performed according to the proposed protocol are provided. Finally additional tests for evaluating the performance of installation details are suggested. The additional tests are for field evaluation of installation details and for laboratory evaluation of installation details with regard to the risk of condensation along window frames.

The detailing of wall-window interfaces and the consequences of defective installation of windows is an on-going concern in North America. This manuscript concerns laboratory evaluation of the water leakage performance of a select set of window-wall interface details. The details were for windows with mounting flanges installed in wood-frame walls sheathed with rigid extruded polystyrene foam. The tests were performed on a single full scale test assembly in which two identical windows were installed by two similar but nonetheless different means. Each detail included a sill pan intended to collect water that gained entry into the assembly and thus was designed to be robust (tolerant of flaws). Tests were performed over a series of different water loading (spray) rates, and over a series of different air pressure differentials at each spray rate. Air leakage rates through the window opening were monitored; they were controlled by a unique methodology. Leakage paths were introduced in the window frames and these paths were alternatively blocked or opened to permit evaluation of the performance of the installation details under two different assumed conditions of window leakage. Air pressure distribution within the assemblies was monitored during spray testing. The wall assembly were designed to permit observation of water entry in it, and to allow measurement of water entry to, or drainage from, various locations within the assembly. Results on water entry and management for the two wall-window interface configurations are given and effectiveness of the details is discussed.

In North America, more than 50 % of low slope roofing applications uses faced rigid cellular polyisocyanurate (hereafter abbreviated as ISO) board as thermal insulation. Long-term performance of a roof assembly is critically dependent on the ISO characteristics during the service period in various environmental conditions. For this reason, the ASTM C 1289-02, “Standard Specification for Rigid Cellular Polyisocyanurate Thermal Insulation Board,” outlines the physical and thermal property requirements for the ISO boards. However, these requirements are based on the available knowledge, information, and consensus at the time of drafting and balloting of the ASTM standard. Nevertheless, the standard gets updated and revised when more credible data are available that solicits revisions of the current standard. This paper presents experimental results from an ongoing pilot research study that critically evaluates the ASTM C 1289-02 specification requirements for the ISO on three engineering properties: (1) dimensional stability, (2) thermal resistance, and (3) compressive strength. Preliminary results from this study reveal many unknown phenomena, particularly regarding the dimensional stability and compressive strength of ISO boards.

Waterworks sludge continues to be an inescapable by-product of the potable water treatment process. Accordingly, final disposal of the sludge remains one of the most significant pressing problems for the potable water treatment industry. The possibility of reusing the sludge as a main substrate in a novel constructed wetland system was investigated in this study. Results show that significant phosphorus (P) and other pollutants removal were achieved in the system. With a mean influent BOD5 (5-day biochemical oxygen demand) and COD (chemical oxygen demand) levels of 392.7 mg/l and 579.8 mg/l, respectively, a removal efficiency of 90.6 % and 71.8 %, respectively, was obtained. P removal was however exceptionally high despite the high influent mean P level of 45.3 mg-P/l, which is about 2-3 times the level of P commonly found in sewage. This is attributable to the P adsorption capacity of the alum sludge and this highlights the benefits of its reuse in the system. The paper presents and discusses the findings from a laboratory scale research, which has potential for further large scale implementation. Other funder Environmental Protection Agency

This paper presents a proposed qualitative framework to discuss the heterogeneous burning of metallic materials, through parameters and factors that influence the melting rate of the solid metallic fuel (either in a standard test or in service). During burning, the melting rate is related to the burning rate and is therefore an important parameter for describing and understanding the burning process, especially since the melting rate is commonly recorded during standard flammability testing for metallic materials and is incorporated into many relative flammability ranking schemes. However, whilst the factors that influence melting rate (such as oxygen pressure or specimen diameter) have been well characterized, there is a need for an improved understanding of how these parameters interact as part of the overall melting and burning of the system. Proposed here is the ‘Melting Rate Triangle’, which aims to provide this focus through a conceptual framework for understanding how the melting rate (of solid fuel) is determined and regulated during heterogeneous burning. In the paper, the proposed conceptual model is shown to be both (a) consistent with known trends and previously observed results, and (b)capable of being expanded to incorporate new data. Also shown are examples of how the Melting Rate Triangle can improve the interpretation of flammability test results. Slusser and Miller previously published an ‘Extended Fire Triangle’ as a useful conceptual model of ignition and the factors affecting ignition, providing industry with a framework for discussion. In this paper it is shown that a ‘Melting Rate Triangle’ provides a similar qualitative framework for burning, leading to an improved understanding of the factors affecting fire propagation and extinguishment.

This paper describes a small study carried out using a hygrothermal simulation tool to investigate the sensitivity of wall performance results to uncertainty in the amount of rain impinging on the wall. Design standards for hygrothermal analysis of proposed designs include methods for selecting appropriate moisture reference years and specify the amount of water that is assumed to intrude into the wall. Weather data used as input for modeling purposes is generally assumed to be reliable, but recent work has shown that there may be considerable uncertainty in the rainfall data. A small study was carried out to investigate the effect of uncertainty of rainfall data on the hygrothermal performance of a typical residential building envelope. Most hygrothermal models require fully populated hourly datasets, which include rain data. Many locations, however, do not have this kind of data although many have qualitative rain data. Ten locations with rain gage data were chosen as typical of most regions of Canada, except for the far north. Different methods in estimating rainfall were considered as well as variations on the amount of rain data were subsequently made. Several performance criteria, including total moisture content and a mold index, were compared. Although the choice of which method for deriving quantities of water from qualitative codes does cause differences in the hygrothermal response and consequently the performance criteria, these differences appear to be manageable. It is suggested that practitioners should show their awareness of the probable level of uncertainty by stating error bands for their predictions of performance. It should be emphasized that the sources of uncertainty dealt with in this small study are not the only ones, but that they do focus on water entry through leakage paths. The natures of the leakage paths likely introduce greater uncertainty, and should also be borne in mind.

The paper summarizes recent results obtained from a new wear test performed on fresh and artificially aged rocks. Four different types of granitic rocks with different mineral compositions and grain sizes were selected for this study. Some important physical and mechanical properties of the rock specimens were also determined. Measurements performed on fresh specimens showed that the wear coefficient is affected by the mineralogical composition, especially the predominant mineral which constitutes the rock. It was determined that wear resistance increased with increasing quartz content. The results also show that there is a positive correlation between the micro-fragmentation rate, during the wear test, and the average grain sizes. Two specimens of the tested granites were subjected to an artificial hydro-physical ageing test. Based on the results of the experiment, it was concluded that the wear testing method is a good indicator of the weathering degree. It was shown that the imposed weathering process decreases the abrasion resistance of the rock and increases its micro-fragmentation ability.

Results of an experimental study to understand crack growth in open threaded bolts and nut-loaded bolts with and without pretension are presented in this paper. Experimental crack growth rates are compared with predicted solutions obtained from known stress intensity factor solutions. For the experiment, a specially designed fixture was used for loading the bolt and the level of pretension was varied by controlling the displacement on the arm of the C section of the fixture. Programmed Hi-Lo fatigue load sequence was applied on a bolt to ensure that decodable marker bands are left behind on the fracture surface, to study the crack growth characteristics. Fatigue crack growth rate was estimated using a scanning electron microscope by identifying crack increment during high stress ratio cycles. This has been compared with predicted crack growth rates using available stress intensity factor solutions. Crack growth at the center of the bolt correlates well with Toribio's (Int. J. Fract., Vol. 53, 1992, pp. 367-385) finite element based predictions for open threaded bolts. Crack growth rate is much higher at the surface than at the center. In case of nut-loaded bolts, available K solutions are found to be inadequate to provide an accurate estimate of crack growth rates at the center of the bolt. Further study is required to characterize the effect of friction, pitch angle, and thread geometry to understand crack growth in bolts. Copyright � 2008 by ASTM International.

International audience; It is now well acknowledged that, after a prototypical loss of coolant accident (LOCA) transient, the resultant mechanical properties of fuel cladding tubes depend strongly on the oxygen content of the residual prior-β layer, as this phase is the only metallic part of the high-temperature oxidized cladding that may show some residual ductility. The aim of this study is to obtain relevant information on the evolution of the mechanical properties, on the one hand, of the prior-β structure as a function of the oxygen content, assuming that there is a critical oxygen content that leads to a ductile-to-brittle failure mode transition at low testing temperatures (20–135°C); and on the other hand, of the α(O) structure as a function of the oxygen content. Sheets of Zircaloy-4, 1 to 3 mm thick, and M5® advanced alloys from AREVA NP have been studied. To obtain different oxygen contents, they were oxidized at high temperature and then annealed under vacuum in order to reduce the oxide layer. Systematic post-treatment measurements of the oxygen concentration and of its homogeneity within the sheet thickness were performed. The different prior-β and α(O) structures thus obtained have homogeneous oxygen content between ∼0.14 wt. % and 0.9 wt. % and ∼2 wt. % and 7 wt. %, respectively. Such oxygen concentration ranges cover the solubility values that are expected in the β phase and in the α(O) phase at high temperatures typical of LOCA transients. Detailed microstructure investigations were subsequently performed on the prior-β structures since it is considered to be the most important layer when regarding the post-quench mechanical behavior of the material. Continuous cooling temperature (CCT) phase diagrams as a function of the oxygen content were established to correctly interpret the results. Electron backscattered diffraction (EBSD) analysis has then allowed the crystallographic orientations and the morphology of prior-β phase sub-grains to be determined. For each considered prior-β grain, it was possible to interpret the data by taking into account the “Bürgers” crystallographic relationship between the parent β phase and the resultant α phase. Complementary electron probe microanalysis (EPMA) was also used. These last experiments have shown a spatial fluctuation of the oxygen content within the microstructure that depends both on the nominal oxygen content and on the cooling rate. Nanohardness measurements were also performed and correlated with this oxygen spatial partition. These measurements proved to be useful for the understanding of the tensile macroscopic mechanical behavior. Finally, on the one hand, tensile tests were performed on prior-β phase at testing temperatures ranging from −100°C up to 260°C. The ductile-to-brittle temperature transition and the mechanical constitutive laws as a function of the oxygen content were then described. These tests show the existence of a ductile-to-brittle failure mode transition at 20°C for a critical oxygen concentration of ∼0.5 wt. %. A detailed fractographic analysis was performed to assess the failure mechanism. On the other hand, four-point bending tests were conducted on α(O) phase at 25°C and 135°C in order to obtain behavior laws. Preliminary finite element calculations were performed to simulate ring compression tests carried out on multi-layered high-temperature oxidized cladding tubes.

A new generation of built-up roofs, known as Adhesive Applied Roofing Systems (AARS), is gaining popularity in North America for low slope application. AARS use no fasteners for components’ attachment and all components (e.g., insulation board, cover board, and membranes) are integrated by application of adhesives. Since there are no metal fasteners, AARS can offer advantages of reduction in moisture migration and thermal bridging. Moisture in the roof envelope can lead generally to material deterioration, structural integrity problems, and the growth of mould. Even though AARS are in commercial use, there is no existing test standard to quantify their wind uplift performance. A new project, “Development of Wind Uplift Standard for Adhesive Applied Low Slope Roofing Systems,” has been initiated in collaboration with industries, university, and the Canadian Government. The project has three major tasks: experimental investigation, formulation of a numerical model, and development of wind design guide and standard. Task 1 completes preliminary investigations by constructing eight mock-ups. All mock-ups had steel deck and polyisocyanurate insulation and varied in adhesives (type, quantity, and application method), cover boards, and membranes. Mock-ups were subjected to both static and dynamic wind loading conditions. Experimental data showed similarity in failure modes and variations in wind uplift ratings. Data show that among the mockups, the weakest link varied depending on the type of adhesives used and component arrangements. This paper presents and discusses the data from this ongoing experimental investigation.

Natural wind hazard damages have been dramatic in recent years, incurring losses of life and property around the world. Wind-induced failure is one of the major contributors to insurance claims, and it is rising. To address these growing concerns, RICOWI (Roofing Industry Committee on Weather Issues) started a Wind Investigation Program (WIP) to investigate the field performance of roofing assemblies after major windstorm events and to factually describe roof assembly performance and modes of damage. As part of this program, Hurricane Charley, which hit Punta Gorda, FL, with winds exceeding 140 mph (63 m/s), was investigated. This paper mainly focuses on the field performance of the low-sloped roofs with three important parameters that were found critical in the failure of the roofing systems, namely, • Effect of corner wind suction, • Effect of parapet, • Effect of internal pressure. For each scenario, first scientific documentation was presented, and then how the field observation reflects the fundamental principles were discussed. Based on this exercise, correlations are developed for roof wind design. In addition, wind design data from the North American codes of practice are also calculated and compared to show the impact of science and field observation on durable roof design. With these illustrations, this paper offers recommendations to advance the roof system design for hurricane-prone regions.

An overview is given of practices for “retrospective” dosimetry based on extraction and counting of niobium and manganese present in typical pressure vessel materials. The main problem of counting structural materials is the overwhelming presence of the nuclide 60Co in the gamma-ray spectra of irradiated materials. Chemical separation of niobium and manganese is needed to determine the induced 93Nbm and 54Mn activities. Procedures have been developed for retrospective dosimetry applicable at normally equipped radiochemical laboratories. Chemical separation procedures have been applied followed by determination of the amount of niobium in dissolution after separation. Special attention has been given to the accurate counting of the very weak X rays of 93Nbm. Different techniques have been applied. Advantages, disadvantages, and the accuracy that can be achieved are discussed. Special attention has been given to the maximum accuracy that can be reached and the minimum amount of niobium that has to be collected to reach this accuracy.

The aim of this study is to investigate the groutability of a microfine cement and silica fume mix grout into fine to medium sands. The basic rheologlcal properties of the cement and silica fume mix suspension (microfine cement: 90 % of solids by weight and silica fume: 10 % of solids by weight) with water/solid ratio of 1.0 are first determined. In addition, penetration performance of the suspension into fine to medium sand specimens having different relative densities is investigated. Unconfined compression and permeability tests were performed on the grouted specimens. It is found that the unconfined compressive strengths of sand specimens permeated the grout mix were higher than those of sand specimens permeated with cement but without silica fume additive. Permeability tests on specimens permeated with cement/silica fume revealed that the permeability in these specimens is lower than that of specimens permeated with cement only. Copyright © 2007 by ASTM International.

The lifetime of thin-walled catalyst-carrying foils is directly linked to the overall amount of aluminum present in the base alloy. Ferritic stainless steel containing more than 7 wt. % of Al represents an interesting material for the production of substrates in catalytic converters because of its good corrosion resistance at high temperature. Despite that, the considerable brittleness of the alloy makes production by means of traditional metallurgical processes difficult. Enriching the steel surface with aluminum avoids these problems and due to the high superficial aluminum concentration, enhances the Al2O3 scale formation in the early stages of the oxidation process. Among several techniques, the co-rolling process appears to be a promising technology for enriching ferritic stainless steel surfaces with aluminum without affecting the structural and mechanical properties of the substrate. This process involves cold rolling the annealed AISI 430 ferritic stainless steel together with aluminum foil to form an Al-steel-Al sandwich. After a preoxidation treatment the resultant assemblies were subjected to cyclic oxidation in air. Their oxidation behavior was then characterized by the weight gain versus the number of cycle curves. Oxides were examined by SEM and the phases were identified by X-ray diffraction (XRD). The results highlight that in the lower range of temperatures (T

There are a number of paintings in the McClung collection [ East Tennessee History Center ] by East Tennessee artists of some notoriety. In the cleaning process, curators had noticed that a painting attributed to Lloyd Branson is actually painted over a previous painting or drawing. This underdrawing is only partially visible with the naked eye. Infrared Reflectography was used to detect and document the underdrawing. The top painting is oriented in the portrait direction with the subject being an American Civil War general by the name of John P. McCown. The underdrawing is oriented in the landscape direction with the subject being a mill scene, complete with a water wheel. Contrast optimization through the use of filters and spatial resolution enhancement by assembling a mosaic from a set of close-up images will be discussed.

Transgenic mouse assays, such as MutaMouse, provide a method to predict the potential target organ carcinogenicity of chemical compounds. As part of a validation study, the effects of the direct-acting mutagens, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and 1-chloromethyl-pyrene (CMP), were investigated for gene mutation in the tissues of MutaMice after a single oral or topical exposure. MNNG (50 or 100 mg/kg) or CMP (25 or 50 mg/kg) were administered as a single oral dose and the mice killed after 3, 7 or 10 days. Mutation frequencies were determined in stomach DNA from both MNNG and CMP-treated animals and in liver DNA from the MNNG-treated animals only. The results, although obtained from a limited number of animals, consistently showed that MNNG increased the mutation frequency in stomach DNA, but not apparently in liver DNA, at each exposure time; no clear increase in mutation frequency was seen in the stomach DNA of CMP-treated animals. Also, MNNG (250 or 500 micrograms) or CMP (5 or 10 micrograms) in acetone were applied as a single dose to the shorn skin of mice 7, 14 or 21 days prior to death. A positive control group was similarly given dimethyl-benz[a]anthracene (DMBA, 40 micrograms) and sacrificed after 14 days. Mutation frequencies were determined in the skin DNA extracted from all animals and in the stomach DNA from MNNG-painted animals only. The results, again obtained from a limited number of animals, clearly showed that all test compounds consistently increased the mutation frequency of skin DNA and that these increases were far greater in the DMBA- and MNNG-treated mice than the CMP-treated mice. No apparent increases were seen in the stomach DNA from the MNNG-painted mice.

Transgenic mouse assays, such as Muta Mouse, provide a method to predict the potential target organ carcinogenicity of chemical compounds. As part of a validation study, 2-acetylaminofluorene was administered as a single oral dose of either 50 or 100 mg/kg. The mice were killed 3, 7, 14, 28, 56 or 112 days after this single treatment. Mutation frequencies were determined in liver DNA. The results showed that a mutagenic response was observed in the mice treated at the highest dose (100 mg/kg) and this increase was expressed from 28 up to 112 days after the single exposure.

The purpose of the paper is to open discussion for an alternative methodology for stability testing of spinal fusion devices that does not require cadaveric tissue. A simulated single level functional spinal unit (FSU) model was used to evaluate spinal fusion devices as an alternative to using cadaveric human tissue models. Initially, this study was proposed as a feasibility investigation prior to investing in a cadaveric study, but was then developed into an alternative, stand-alone method that eliminates variabilities associated with cadaveric tissue testing for providing comparison testing between spinal devices. The objective of this paper is to present the development of the synthetic FSU model and the apparatus for providing kinematic stability testing on lumbar interbody spinal devices. The synthetic model geometry was based on morphological parameters for the lumbar spine using rigid foam per ASTM F1839. A universal servo-controlled test frame provided the pure moment loading through a system of cables and pulleys for the application of flexion-extension, lateral bending, and axial rotation. Comparable testing was performed using short cyclical, fully reversing runs up to 50 cycles where the last ten cycles were evaluated.

The weatherability of construction sealants is a highly important performance criterion for the prediction of their service lives. Currently, the evaluation of a sealant’s surface weatherability is carried out mainly via qualitative visual judgment. One objective of this paper is to establish a quantitative method for the assessment of surface degradation. A further objective is the evaluation of the relationship between outdoor and accelerated exposure with regard to surface degradation. The understanding of this relationship is important for the shortening of the development cycle and the prediction of a sealant’s service life. The paper presents information on the weatherability of construction sealants based on a recently developed test specimen design that allows simultaneous exposure of the sealant to forced compression and extension movement in a single specimen with cyclic movement and weathering carried out simultaneously. A quantitative method for the assessment of surface cracks is employed, and the relationship between outdoor and accelerated weathering exposure is evaluated by using metrics that indicate the degree of surface cracking as a new semi-quantitative criterion of surface degradation.

The analysis of in-service lubricating fluids is a useful tool in determining the state of both the fluid and the equipment being lubricated. Many laboratories provide analysis services for in-service lubricating fluids. The results of the analyses performed are often tracked over time to allow for the observation of trends in the test results. The analysis of in-service lubricating grease is a more challenging task; since the amount of grease in many applications is quite small, the grease may be partially or totally replaced each time new grease is added, and access to the lubricated contact zone may be difficult. Many commercial in-service lubricant analysis laboratories lack the specialized test equipment required for grease analysis, so that type of analysis is performed by a limited number of laboratories, primarily those of the grease manufacturers. Various techniques are employed to determine both the macro and micro condition of in-service lubricating grease. The strengths and weaknesses of those techniques are discussed herein.

This paper shows the evolution of the surface crack front in round bars constituted of different materials (determined by the exponent m of the Paris law), subjected to fatigue tension loading (with free ends) or fatigue bending loading. To this end, a numerical modeling was developed on the basis of a discretization of the crack front (characterized with elliptical shape) and the crack advance at each point perpendicular to such a front, according to a Paris-Erdogan law, using a three-parameter stress intensity factor (SIF). Each analyzed case was characterized by the evolution of the semielliptical crack front, studying the progress with the relative crack depth a/D of the following three key variables: (i) crack aspect ratio a/b (relation between the semiaxes of the ellipse which defines the crack front); (ii) maximum dimensionless SIF; and (iii) minimum dimensionless SIF.

Currently, the (pozzolanic) strength activity indices of fly ashes and natural pozzolans are typically evaluated using the procedures outlined in ASTM C311 [“Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete,” Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2007]. In this test, the 7 and 28 d compressive strengths of mortar cubes with a 20 % mass replacement of cement by pozzolan are compared to those of a control without pozzolan, at constant flow conditions. In its current form, this procedure confounds two other properties of the pozzolan with its strength activity, namely its density and its water-reducing/increasing capabilities. In this study, the current C311 testing procedure is evaluated against an alternative in which the 20 % fly ash replacement for cement is performed on a volumetric basis and the volume fractions of water and sand are held constant, which should provide a true evaluation of the strength activity index of the pozzolan, free of these confounding influences. Class C and Class F fly ashes, a natural pozzolan, and a sugar cane ash are evaluated using both approaches, with some significant differences being noted. For a subset of the materials, the strength measurements are complemented by measurements of isothermal calorimetry on the mortars to an age of 7 d. For the constant volumetric proportions approach, a good correlation is exhibited between the cumulative heat release of the mortar at 7 d and the measured 7 d strength, suggesting the potential to evaluate 7 d pozzolanic activity via calorimetric measurements on much smaller specimens.

The heat flow during the unidirectional downward solidification of Al-7Si and Al-12Si alloys was analyzed using thermal analysis technique and inverse modeling. Chills instrumented with thermocouples were brought into contact with a small pool of liquid metal so as to minimize the effect of convection caused by pouring and temperature gradients. Modification melt treatment resulted in an increase in the cooling rate of the solidifying casting near the casting–chill interfacial region. The corresponding interfacial heat flux transients were also found to be higher. The thermal diffusivities of alloys were measured using a laser pulse technique and were found to be higher for modified alloys. However, the increase in the heat flux transients was attributed mainly to the improvement in the casting–chill interfacial thermal contact condition brought about by the decrease in the surface tension of the liquid metal upon the addition of sodium.

The objective of this study was to investigate how the axial gripping capacity can be affected by varying the tightening torques applied to the set screws in a pedicle screw ASTM F1798 subassembly. Although the current ASTM F1798 standard indicates that all tightening loads to the locking mechanism be applied as specified by the manufacturer, the torque limiting instruments used in the field can have nominal upper and lower torque limits. The interconnection assemblies were assembled using a multi-axial screw, spinal rod, and set screw. Six groups were assembled using different types of spinal rods. Each group was sub-divided into three groups each containing five interconnection assemblies. The three sub-groups of interconnection assemblies were locked to the nominal torque value as indicated by the manufacturer technique, lower limit, and higher limit respectively. Static axial grip testing was performed according to ASTM F1798 guidelines. Axial gripping capacity was influenced by the nominal tightening torque and lower tightening torque and holds true regardless of rod diameter and rod material. There is no significant difference in the axial gripping capacity between the nominal tightening torque and higher tightening torque. These results indicate that the set screw tightening torque has an effect on the gripping capacity and could potentially affect yield load, ultimate load, and failure modes when performing ASTM F1717 compression bending testing. With the wide range of materials used to manufacture pedicle screw systems and the processing techniques that are currently available, e.g., anodization and shot peening, critical thinking should be put into determining if the torque applied to the system represents a worst-case scenario.

A close correlation between the mechanical behavior changes of metal-metalloid glasses and their relaxation spectrum heat emissions has been found. The criteria of crystallization and ductile-brittle transition for these kinds of metallic glasses (MGs) have been established. They correspond to the heat emission balance between the low- and high-temperature parts of the relaxation spectrum. The model of MGs as a system constituting an additive sum of elementary two-level transitions with continuously distributed activation energies is proposed for the analytical description of the relaxation spectrum and its parameters. The methods developed in the approximation of the model permit the determination of the current state of MG materials at an arbitrary temperature, as well as forecasting of their ductile-brittle transition and crystallization according to heat emission alterations of the relaxation spectrum.

Until now, most of the detailed characterizations of the M5 corrosion behaviour were performed under standard PWR operating conditions, under moderate Li content and moderate temperature of the primary coolant. In this study, in addition to these standard conditions, two demanding operating conditions were explored: increased Li chemistry and elevated temperature. The objective is to establish whether these more demanding conditions have an impact on the structure of the oxide layers formed, on Nb, Li and B contents in these layers and on Hydrogen pickup of the cladding. The structure of oxide layers was studied by microscopy, the Nb content and distribution by Electron Probe Micro Analysis, the Li and B contents and distributions by Nuclear Reaction Analysis and the hydrogen pickup by gas extraction. It was observed that the stability of the corrosion behaviour of M5 is not affected by increased Li or elevated temperature conditions. The hydrogen pickup fraction of M5 is not modified by increased Li conditions or by irradiation temperature with measured contents (

In vitro wear tests results and 2-year follow up radiographic analyses of implanted fixed- and mobile-bearing LPS Flex knees are compared. The two knee designs use gamma-sterilized GUR 1050 ultra high molecular weight polyethylene (UHMWPE) patellae and tibial inserts, and the same CoCrMo alloy (ASTM F 75) femoral components. The in vitro wear tests were performed on six fixed- and six mobile-bearing knee implants using modified ISO 14243-3 load and kinematic waveforms. Tests were conducted at a frequency of 1 Hz for 5 × 106 cycles (Mc) in bovine serum lubricant. Two year follow up radiographic analyses were performed on 341 patients implanted with 173 mobile- and 168 fixed-bearing implants. Average accumulative in vitro polyethylene wear rates of the mobile- and fixed-bearing knees were 19.9 ± 5.1 mg/Mc and 14.2 ± 2.1 mg/Mc, respectively. There is no statistically significant difference in the wear rates of both devices (p > 0.05, Mann–Whitney test). Overall survivorship at two years with revision for any reason as the endpoint was 99.3 % for the mobile group and 100 % in the fixed group. There was no evidence of tibial, femoral, or patella bone loss at the two year follow up. The mean active range of motion increased from 110.8° to 127.0° in the mobile- bearing group and from 110.7° to 127.2° in the fixed-bearing one. Overall, radiographic evaluation showed similar performance of both devices.

In the current version of ASTM F2624, the center of rotation (COR) is not specified. Potentially, each device can be tested using a different COR, which subsequently makes a direct design comparison of results difficult. Four posterior dynamic stabilization (PDS) devices (Dynesys, DYN, Zimmer; DSS, Paradigm Spine; and two Aesculap implant concepts) were tested in comparison to a rigid-fixation device and to the native situation of the lumbar spine on fresh-frozen human lumbar spines (L3–L5). The instrumented level was L4–L5. The PDS systems have axial compressive stiffness values ranging from 10 N/mm to 230 N/mm and were all made compatible to connect with the pedicle-screw system. The specimens were loaded in a spinal simulator, applying pure moments for flexion/extension, lateral bending and axial rotation (+/−7.5 Nm) with a defined velocity. The COR was analyzed based on the data measured with a 3-dimensional (3D) motion-analysis system. The effect of the PDS on the location of the COR is most pronounced in the sagittal plane. In general, the higher the implant stiffness, the more the COR shifted in a posterior direction. The DYN had a similar COR to the rigid fixator. However, the PDS systems with low axial compressive stiffness values (range: 10–70 N/mm) showed very similar results on CORs, which are located in the region of the posterior border of the intervertebral disc. In the frontal and transversal plane, the COR was found to be close to the native situation for each system. Therefore, for PDS devices with low implant stiffness, the location of the COR varies only marginally and can be specified for a test setup. An initial proposal that will allow side-by-side comparison for these kinds of PDS systems is given and the feasibility of the new test setup could be proven for all three loading conditions.

The current American Association of State Highway and Transportation Officials standard on crushed concrete in base applications (M 319-02) allows up to 5 % brick by mass, and more with the approval of the engineer; however, in some regions the brick content may be greater than 10 %. More than 41 states allow the use of crushed concrete in highway applications, but only a handful allow the use of building derived concrete (BDC) or mixed stream crushed concrete. Barriers to increasing the appropriate use of BDC in highway applications include a lack of data comparing BDC properties and performance to natural aggregates, as well as data that pavement engineers can use for design. This research has focused on characterizing BDC that was screened to meet New Hampshire Department of Transportation specifications. The gradation, optimum water content, unit weight, and resilient modulus were measured for the BDC and for the control materials, which were a crushed stone and a sand. The resilient modulus was measured using both a laboratory triaxial cell, and a light falling weight deflectometer (LWD) in a test pit. The resilient modulus of the BDC exceeded that of the control materials as measured in the laboratory and using the LWD. In addition, the laboratory resilient modulus showed good correlation with the LWD stiffness. These results suggest that BDC would perform as well as natural aggregates in base course applications.

To estimate the temperature distribution, stress distribution, and stress direction in a blade in service, the morphology of γ′ precipitates in Ni-based superalloy serviced in the first stage low pressure turbine (1st LPT) blade of a jet engine was investigated before and after aging. Using a field emission scanning electron microscope, microstructures were observed in forty portions of the blade. Most of the γ′ precipitates remained cuboidal in the serviced blade. Many secondary γ′ precipitates were observed in the γ matrix at the root part. In contrast, there were no secondary γ′ precipitates at the leading edge of the tip part. After simple aging, low-completion rafted γ/γ′ structures appeared on the suction side of the 70 mm part, while in other portions, coarsening of the γ′ precipitates was observed. Therefore, the leading edge of the 1st LPT blade tip was exposed to the highest temperatures in service. However, the stresses were extremely low in all portions of the blade.

The objective of this study was to investigate the influence of the filler metal on the microstructure and mechanical properties of ferritic stainless steel AISI 444 welded using two types of filler metal of austenitic stainless steel. Microstructure examinations showed that in both welded joints grain growth occurred in the heat affected zone (HAZ). The results also showed that the fusion zone of the weld joints using E309L filler metal presented a discontinuous network of delta ferrite unlike the fusion zone of the weld joint using E316L. Tensile tests showed that the failures of specimens always occurred in the HAZ and that the weldments using E316L filler metal presented tensile strength lower than that of the weldment using E309L filler metal. In the fusion zone of the weldments using E316L filler metal, values for hardness were found to be higher than those found in the fusion zone of the E309L filler metal.