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The initial microstructure of cold-worked Ti-added 14Cr–15Ni stainless steel was modified through short-term aging and its influence on creep properties has been investigated at a test temperature of 973 K and two stress levels of 150 and 175 MPa. The improvement in rupture life of the condition comprising of post-aging was nominal at 175 MPa, but enhanced more than two times at 150 MPa when compared to the condition which comprised of prior cold work alone. Microstructural examination after creep testing showed that though M23C6 type of precipitates was prominent in both conditions, their size distribution varied with respect to processing condition (viz., one with prior cold work and another comprising of prior cold work followed by aging) as well as applied stress. Retention of cold work-induced dislocation structures aided by secondary TiC precipitates in the aged condition enhanced the rupture life at 150 MPa. Extensive recovery of the dislocation substructure was observed in the unaged condition tested at the same stress level. The size distribution of the dimples observed from the fractographs could be correlated with the extent of creep-induced cavitation. This work describes how the two preprocessing conditions influence the nucleation of M23C6 and secondary TiC precipitates during creep deformation. [ABSTRACT FROM AUTHOR]

The AA2219 is an Al-Cu alloy with widespread engineering applications. The sheet parts of this alloy are produced by metal forming and are subjected to age hardening (e.g., T6 temper) for strengthening. The cold work in metal forming affects the ageing behavior of alloy and hence the resulting mechanical properties. In this research, a novel forming technique namely Incremental Forming with three different forming-ageing routes is employed to produce age-hardened AA2219 parts. The resulting microstructure evolution, mechanical properties, and residual stresses are examined. The results reveal that forming imposed cold work (35% plastic strain) enhances the sheet strength and hardness to a certain extent, which can be further enhanced by opting an optimum forming-ageing route. Similarly, the residual stresses also show sensitivity to the forming-ageing route opted. Based upon extensive analysis of the experimental results, it is concluded that the [O-IF-ST-T6] route is the most appropriate route for producing age-hardened parts with high strength, hardness and ductility, and low residual stresses (where O, IF, ST, and T6 represent parent, incremental forming, solution treatment and T6 ageing, respectively). This route is found to offer a gain of 238% in the tensile yield strength, 151% in the ultimate tensile strength, and 200% in the hardness with respect to the parent metal. Further, from several correlations drawn between mechanical properties and microstructural quantities, namely grain size, and precipitate's size and density, strengthening mechanism is revealed for the reported gains. [ABSTRACT FROM AUTHOR]

Austenitic stainless steel has high toughness and plasticity; however, it tends to exhibit low yield strength, which severely limits the widespread application of this steel. It can be strengthened by cold working; however, this will cause many defects in the structure. Therefore, annealing treatment must be carried out before use. In this paper, the effects of annealing treatment at different temperatures and times on the microstructure and mechanical properties of cold-rolled 305 stainless steel sheet were studied and the theoretical mechanism was further analyzed to provide better theoretical guidance for production and application. It was found that the microstructure grains obtained by annealing at 850 °C for 30 s were finer and more uniform, and the mechanical properties were also the best, which met the requirements of strong plasticity. Therefore, the rolling and annealing experiments could be carried out again under this annealing condition, and the requirements of the finished product could be finally obtained. At this time, the thickness of the plate was about 0.15 mm, the yield strength was 1238 MPa, and the permeability was below 1.02, which met the production requirements of the metal mask plate. [ABSTRACT FROM AUTHOR]

T8 treatment includes solution treatment, cold working and artificial aging treatment. T8 treatment can greatly improve the hardness and strength of 2024 aluminum alloy without reducing the corrosion resistance. The effect of 0, 1, 2, 3, and 4% cold-drawing deformation on the microstructures of the alloy was observed by transmission electron microscopy, and properties of the alloy was investigated by hardness tests, tensile tests and electrochemical corrosion tests. The results show that the mechanical properties and corrosion resistance of cold-drawing deformed 2024 aluminum alloy are better than those of non-deformed alloy. Compared with AA2024-T6, AA2024-T8 with 2% cold-drawing deformation has a higher hardness by 11.3%, and a higher tensile strength by 10.8%. The improvement of the properties of AA2024-T8 is mainly due to the interaction between dislocations and precipitates. With the increase in cold-drawing deformation, the nucleation points of precipitates in AA2024-T8 gradually increase, and precipitates are gradually coarsened under the same artificial aging treatment. [ABSTRACT FROM AUTHOR]

The combined impacts of copper content, cold working and homogenization in aluminiumsilicon alloys were examined using microstructure study, thermodynamic modelling, image analysis and hardness measurement. Two aluminium alloys of varying copper contents were cast in a permanent mould using induction furnace. Microstructural observation revealed the formation of varying amount of intermetallic phases due to the presence of copper. Image analysis confirms the relative changes in percent phase fractions owing to presence of copper as intermetallic phases increases. Al2Cu phase was most favoured with increasing copper. Cold working was performed by reduction of 5%, 10% and 15% of the cast alloys by equal amounts of strain. Hardness measurements indicated increase in hardness values attributed to both higher amounts of copper and cold working. Al2Cu phase was predicted contribute compared to Al7Cu4Ni and Alpha phases. Homogenization at 300°C for 4 hr would suffice to obtain a uniform structure. The reasons for changes in microstructure and mechanical properties for different copper content were established by thermodynamic phase fraction calculation. Higher amounts of copper leads to greater volume fractions of intermetallic phases. Using solidification calculations, it is found that copper in liquid encourages dendrite formation which was also evident from microstructure. [ABSTRACT FROM AUTHOR]

Cu-Ni-Si alloy is the key raw material for the lead frame of large integrated circuits. The disordered grain orientation of alloy billet, high hardening rate, residual stress, and poor surface quality of cold working strips seriously affect its processability. In order to improve the cold-working properties of Cu-Ni-Si alloy, two kinds of C70250 copper alloy strips were produced through hot mold continuous casting (HMCC) and cold mold continuous casting (CMCC) technology. The effects of solidified microstructure on the cold-working deformation behavior, mechanical properties, and residual stress of the alloy were studied. The results show that C70250 copper alloys with columnar grain and equiaxed grain were prepared through HMCC and CMCC. After a 98% reduction in cold rolling, columnar grain strip surface quality was very good, and the elongation was still as high as 3.2%, which is 2.9 times that of equiaxed grain alloy. The residual stress of equiaxed grain strips reached 363 MPa, which is 2.7 times that of columnar grain strips. During the cold rolling process, equiaxed grain strips are prone to cause intersecting plane dislocations, stacking faults, shear bands, and grain breakage during large deformation cold rolling. The columnar grain strip causes parallel plane dislocations, stacking faults, and shearbands. Furthermore, the deformation structure was found to be uniform, and, ultimately, the alloy formed a fibrous structure. Therefore, the elongation and latter distortion of columnar grain strips improved after being put through large deformation cold rolling, which greatly reduced residual stress. [ABSTRACT FROM AUTHOR]

In the present paper, an investigation was carried out to understand the microstructure or secondary phase changes formed during thermal ageing at nose temperature (where Cr diffusion was faster) and its influence on the pitting corrosion behaviour of type 316LN SS with marginally lower Cr in as-received (AR) and 10% cold work (CW). X-ray diffraction studies confirmed Cr23C6 and Cr2N in AR and CW conditions. On thermal ageing, AR material from 0 to 10 h and CW from 10 to 24 h, although with lower Cr, the degree of sensitisation (DOS) and pitting potential (Epit) were insignificant due to nitrogen where as above 10 h in AR condition and below 10 h in CW condition resulted reductions in pitting potential (Epit) in different chloride mediums. These results provide new insights on the interplay between pitting, microstructures, alloying elements. [ABSTRACT FROM AUTHOR]

Cu-Ti alloys were strengthened by β'-Cu4Ti metastable precipitation during aging. With the extension of the aging time, the β'-Cu4Ti metastable phase transformed into the equilibrium β-Cu4Ti phase. The Cu-3.5 wt% Ti(Cu-4.6 at% Ti) alloys with different processing were aged at different temperatures for various times after solution treatment at 880 °C for 1 h. The electrical conductivity of samples under different heat treatments had shown an upward trend as time increased during aging, but the hardness reached the peak value and then decreased. The hardness and electrical conductivity of the samples with 70% deformation after aging are higher tha n the samples without deformation. Deformation after aging would cause the metastable phase to dissolve into a matrix. The best combination value of conductivity and hardness is 13.88% IACS and 340.78 Hv, and the optimal heat treatment is 500 °C for 2 h + 70% deformation + 450 °C for 2 h. [ABSTRACT FROM AUTHOR]

High-N Ni-free stainless steels are used for their excellent mechanical properties combined with their high corrosion resistance, especially for biomedical applications. Even though it is well-known that secondary hardening during annealing after cold working has been observed in many materials, this phenomenon was not reported for these materials, one of the best known being Biodur108©, although numerous efforts have been made to increase its hardness. In this work, thermomechanical treatments at low temperature of cold-deformed Biodur108© were conducted to increase the hardness. Hardness as high as 830 Hv was obtained. For this material, the annealing of a deformed sample at intermediate temperature leads to a secondary hardening phenomenon. The mechanisms responsible for this secondary hardening were analyzed. It was found that for deformed samples, annealing at 575 °C leads to the formation of small Cr2N precipitates along grain boundaries and sub-grain boundaries, and simultaneously with a new body-centered cubic (BCC) phase that possesses a super structure. The newly formed phases have sub-micrometric grain sizes. [ABSTRACT FROM AUTHOR]

Featured Application: Manganese bronzes are applied in marine environments, for example, gate valve stems due to their characteristics of high mechanical strength and corrosion resistance. Each element present in the chemical composition of the alloy contributes to the properties required in this application, such as: lead contributes to machinability, iron improves tensile strength, tin increases corrosion resistance and manganese contributes to elastic properties. The study of the increase in mechanical properties is crucial for a better understanding of alloy hardening, as well as for the optimization of properties and manufacturing processes. The present study evaluated the influences of different temperatures during heat treatment on the microstructure and mechanical properties of the manganese bronze alloy. During heating, there was a decrease of stored energy in the form of crystal defects due to the mechanisms of rearrangement and the annihilation of dislocations, followed by nucleation and grain growth. Initially, the samples were drawn using 34% cold work. Then, the specimens were heat-treated for one hour with different temperatures ranging from 200 to 750 °C, increasing by 50 °C for each sample. The chemical composition characterization was determined by X-ray fluorescence spectrometry (XRF). The mechanical property characterization involved the Vickers hardness, tensile strength, yield strength, and elongation. For the microstructural analysis of the samples, optical microscopy and scanning electron microscopy were used. The results showed an increase of elongation and decrease of the Vickers hardness and tensile and yield strengths with the increasing annealing temperature. The Hollomon model was used to investigate the strain-hardening behavior in all specimens. The (n) strain-hardening coefficient and the (K) strength coefficient were calculated, and the correlation with the increase of temperature occurred with the increase of n and variation of K after the recrystallization temperature. [ABSTRACT FROM AUTHOR]

In this study, the influence of the variable content of Al, Ni, Fe on the grain refining and the change of mechanical properties of aluminium bronze cast into iron ingot mould was investigated. The ingots were tested for susceptibility to cold plastic working in the rolling process. It was shown that a small amount of iron (0,8 wt. %) influenced a significant level of grain refining and improvement of mechanical properties. For alloys with an increased content of Al, Fe and Ni, the maximum value of the true strain of 0,36 was achieved in the cold rolling process. The possibility of achieving similar mechanical properties for alloy with reduced content of alloying elements was demonstrated after applying the true strain of 0,61. [ABSTRACT FROM AUTHOR]

The Zr-2.5Nb alloy pressure tubes manufactured by Water Quenched and Aged (WQA) fabrication route has reportedly exhibited superior resistance against in-reactor dimensional changes. WQA route comprises three consecutive thermo-mechanical treatments viz., solution heat treatment (SHT), cold working and vacuum aging, which govern the final microstructure and therefore fracture toughness of the pressure tube material. This work describes the influence of SHT soaking duration, degree of cold working and aging temperature on the microstructure and fracture toughness of WQA Zr-2.5Nb alloy. WQA pressure tubes are expected to have better resistance to in-reactor dimensional changes. However, if proper care of hydrogen absorption during thermo-mechanical processing is not taken, though resistance to creep will improve expectedly but fracture toughness at ambient temperature will deteriorate. [ABSTRACT FROM AUTHOR]

A technique of deformation heat processing for Al–Si based alloys is proposed which can significantly increase their both ductility and strength and also reveals additional reserves for their strength and hardness increasing through cold work hardening. The method includes serial of small hot plastic deformations with intermediate cooling and short annealing. This makes the silicon inclusion rather small with shape close to spherical, which leads to the ductility increasing. Then a work hardening processing could be performed for the material. Finally, both ductility and strength appear higher than in the initial cast state. [ABSTRACT FROM AUTHOR]

The effects of thermal aging and prior cold work at 700 °C on the kinetics of sensitization (i.e., corrosion failure) of high-manganese austenitic stainless steel have been studied by conducting microstructural analysis, transmission electron microscopy analysis, and double-loop potentiostatic reactivation analysis. Thermal aging at 700 °C caused an increase in preferential grain boundary attack (dual and ditch type) and degree of sensitization, and the intensity of these effects increased with the increase in time duration of thermal aging. With cold working, a widespread grain area attack has been found with no preferential grain boundary attack; however, an increase in degree of sensitization values has been observed. Transmission electron microscopy and energy-dispersive x-ray spectroscopy showed the presence of carbides on the grain area, i.e., transgranular carbide precipitation. The findings conclude that the cold-worked thermal-aged high manganese austenitic stainless steel becomes susceptible to intergranular corrosion failure due to sensitization and transgranular corrosion. [ABSTRACT FROM AUTHOR]

WC-10Ni powder was deposited on Al, Cu, and low carbon steel substrates by cold gas spray method under the process gas pressure of 15 and 35 bar. The effect of substrate on the deposition phenomenon, microstructure, and microhardness of the coatings was evaluated. The cross-section morphology of the coating was studied by the scanning electron microscopy (SEM). The pinning of WC particles caused a high strength between the coating and the substrate. Crack initiation and propagation during cold spraying process, due to the high level of cold working, was the main reason for the high level of porosity of the deposited coating on the Cu substrate. It was found that low carbon steel substrate, for its higher hardness compared to aluminium and copper, experienced minimum deformation. Moreover, the harder the substrate, the higher the microhardness and fracture toughness and the lower the porosity of the coating. [ABSTRACT FROM AUTHOR]

Cold work dies (of Cr12MoV) surface of the WC/Ni composite coating prepared by laser cladding can be used to quickly repair worn areas of dies. The composition, hardness, fracture morphology, microstructure, and shear strength of the coating were characterized by microhardness tester, universal tensile testing machine, XRD, EDS, and SEM. The results show that the main phase of the coating is composed are M23C6, FeNi3, Cr7C3, WC, W2C, Cr2B, Fe2B, and W2B. The change of scanning speed only changes the diffraction peak, but has little effect on the internal structure and strengthening mechanism of the coating. With the decrease of scanning speed, the powder deposition density per unit time increases, and a large number of pores and unmelted particles are mixed in the coating, which weakens the bonding strength between the coating and the substrate, and the fracture mechanism of the coating changes from quasi-cleavage fracture to brittle fracture. [ABSTRACT FROM AUTHOR]

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Copyright of Ingenius, Revista Ciencia y Tecnología is the property of Universidad Politecnica Salesiana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High-manganese Hadfield cast steel is commonly used for machine components operating under dynamic load conditions. The high fracture toughness and abrasive wear resistance of this steel are the result of an austenitic structure, which—while being ductile—at the same time tends to surface harden under the effect of cold work. Absence of dynamic loads (e.g., in the case of sand abrasion) causes rapid and premature wear of parts. To improve the abrasive wear resistance of high-manganese cast steel for operation under the conditions free from dynamic loads, primary niobium carbides are produced in this cast steel during the melting process to obtain in castings, after melt solidification, the microstructure consisting of an austenitic matrix and primary niobium carbides uniformly distributed in this matrix. The measured hardness of the tested samples as cast and after solution heat treatment is 260–290 HV and is about 30–60 HV higher than the hardness of common Hadfield cast steel, which is 230 HV. Compared to common Hadfield cast steel, the abrasive wear resistance of the tested high-manganese cast steel measured in the Miller test is at least three times higher at the niobium content of 3.5 wt%. Increasing the niobium content to 4.5 wt%. in the tested samples increases this wear resistance even more. [ABSTRACT FROM AUTHOR]

To explore an appropriate intermediate temperature of heat treatment during the cold working of UNS N10003 alloy, the influence of heat treatment temperature, time, the induced deformation, the mechanical properties, and microstructures by the pre-stretching method was investigated systematically. The results showed that after heat treatment (performed at 760 °C, 6 h), the strength was not reduced, and the elongation was not improved efficiently. However, after only 30 min of heat treatment at 870 °C, their strength was efficiently reduced, and their elongation was substantially improved, reaching the original sample level. Moreover, no apparent changes were observed with the extension of heat treatment time. The morphology of the microstructures and fractures indicated that the recovery and recrystallization process occurred at the temperature of 870 °C during the heat treatment, which resulted in the residual stress relieving and microstructural reconstruction. Correspondingly, the fractographs were also transformed from cleavage to ductile. Therefore, the heat treatment during the cold working should be carried out at 870 °C, enhancing energy- and cost-efficient production of UNS N10003 alloy. [ABSTRACT FROM AUTHOR]

Deep drawing process is one of the most important processes of sheet forming, which is widely used in the deformation of metal sheets in order to produce parts with complex geometry. Several studies have been carried out on some steels with good formability such as low-carbon and austenitic stainless steels. Among different types of plain carbon steels, high carbon eutectiod steels are capable to withstand cold and warm working without formation of any defect, due to their fully pearlitic microstructure without the presence of proeutectoid phases and nano-sized cementite lamella. However, no comprehensive research has been conducted on the deep drawing process of eutectoid steel. In the present research, the formability of CK75 steel sheets was experimentally evaluated using warm deep drawing process. Warm deep drawing process of the CK75 steel was studied in the temperature range near and below the eutectoid transformation temperature. The results show that deformation at 700°C (near to the eutectoid temperature) lead to the uniform distribution of thickness and less instability. On the other hand, maximum instability (e.g. thinning) was obtained by warm deformation at 550°C. At the temperature above the eutectoid transformation temperature, due to the formation of multi-phase structure and non-uniform distribution of cementite particle, the workability was reduced and led to the occurrence of rupture during deep drawing. [ABSTRACT FROM AUTHOR]

• The precious metal based High-Entropy Alloy (HEA) AuCuNiPdPt is of single phase fcc structure in the homogenised state. • Decomposition occurs during annealing AuCuNiPdPt at intermediate temperatures. • AuCuNiPdPt deforms by deformation twinning and dislocation slip at room temperature. • AuCuNiPdPt shows a high yield strength of 820 MPa and a high yield ratio of 0.66 at room temperature as well as significant strain hardening during deformation. • The strengthening mechanisms of AuCuNiPdPt are assessed. The precious metal based High-Entropy Alloy (HEA) AuCuNiPdPt crystallises in a face-centred cubic structure and is single phase without chemical ordering after homogenisation. However, a decomposition is observed after annealing at intermediate temperatures. This HEA shows extended malleability during cold work up to a logarithmic deformation degree of φ = 2.42. The yield strength ranges from 820 MPa in the recrystallised state to 1170 MPa when strain hardened by cold working with a logarithmic deformation degree of φ > 0.6. This work hardening behaviour is traced back to a steep increase in dislocation density as well as in deformation twinning occurring at low strain. The microstructure and the mechanical properties of AuCuNiPdPt are assessed in detail by various methods. EBSD and TEM analyses reveal mechanical twinning as an important deformation mechanism. The high strength in the recrystallised state is evaluated and found to originate predominantly upon solid solution strengthening. [ABSTRACT FROM AUTHOR]

The effect of cold work (CW) on the microstructure and corrosion fatigue (CF) resistance of 316 LN stainless steel (SS) using microscopic, electrochemical and surface analytical methods was investigated. The CF resistance increases with CW. The fractographs revealed that the crack growth zone was minimum for the base metal as compared to CW SS. Fatigue-tested sample revealed a slip offset was high for as-received, while not much significant difference for 5 and 20% CW SS at low mean stress levels. The presence of NH4 improved passivity by the formation of nitrate ions that inhibits anodic dissolution. [ABSTRACT FROM AUTHOR]

Machinery components used for mining and mineral processing activities are often subjected to high impact loads and wear which have placed demands for the development of materials with high resistance to dynamic loads and aggressive wear conditions. In this study, a multilayered cladding of high alloyed cold work tool steel (X245VCrMo9-4), interlayered with Hadfield steel (X120Mn12) plates, which was also used as substrate using super-solidus liquid-phase sintering technique was investigated. A stack of the cold work tool steel powder was prepared with interlayered X120Mn12 steel plates in an alumina crucible at tap density with the substrate placed on it and was sintered in a vacuum furnace at 1250 °C at a heating rate of 10 K/min, held for 30 min under a nitrogen atmosphere at 0.08 MPa and furnace-cooled. Sample from the as-sintered cladding was subjected to austenization at 1000 °C, quenched in oil and tempered at 150 °C for 2 h. Samples were subjected to microstructural examination using optical and scanning electron microscopy. The microstructural investigations were supplemented by hardness and impact wear tests. Computational thermodynamics was used to support experimental findings. The results revealed that a near-net densification of the sintered X245 was achieved with 99.93 ± 0.01% density. The sintered X245 was characterized by a dispersion of vanadium carbonitride precipitates, especially at the grain boundaries. The heat-treated X245 sample had the highest hardness of 680 ± 7 HV30 due to the matrix of tempered martensitic microstructure when compared to as-sintered with hardness of 554 ± 2 HV30. The X245/X120 interface was characterized by diffusion of Cr, Mo, Mn and C, which resulted in metallurgical bonding between the cladded materials. The impact wear resistance of the sintered X245 was eight times that of the X120; hence, a tough and wear-resistant tool is anticipated when the X120 work hardened in service. [ABSTRACT FROM AUTHOR]

Poor performance of advanced engineering materials, during long term servicing at high temperature, is closely related to thermal stability of the microstructures. Instability of the microstructures specially in respect of the grain size, deteriorates mechanical properties and also has a detrimental effect on physical and functional properties of the components. In this respect, any of the High Entropy Alloys (HEAs) as a promising candidate has attracted academic and industrial attention according to their excellent high-temperature resistance and thermal stability compared with conventional engineering alloys. In this study we investigated effect of alloying element, annealing conditions (temperature, time), and pre-treatment (cold working) on grain growth behavior of HEAs. The retarding/accelerating effect of sluggish diffusion, solute drag, local concentration fluctuation, Zener factor, stacking fault energy, second phases, and fine particles were discussed in details. Grain growth kinetics was investigated with emphasis on grain growth exponent (n) and correlated activation energy (Q). Effectiveness of Hall-Petch relationship was finally studied to consider the frictional stress and slip transition behavior across grain boundaries. This review, overall, indicates high thermal stability of HEAs and also which one's high capability to be considered in high temperature engineering applications. [ABSTRACT FROM AUTHOR]

Conventional high silicon steel possesses extremely low plasticity at room temperature, where even zero elongation can take place, so it is pretty difficult to implement cold working. In the present study, the novel Fe-6.5Si-2Cr-12Ni (wt%) high silicon steel is derived from addition of Cr and Ni, and in particular, Fe-6.5Si-2Cr-12Ni high silicon steel possesses much higher room-temperature plasticity than conventional high silicon steel and simultaneously it keeps very high tensile strength, where it possesses an elongation of 15.84% as well as an ultimate tensile strength of 1403.07 MPa at room temperature. An excellent combination of mechanical properties for Fe-6.5Si-2Cr-12Ni high silicon steel is attributed to refinement of grain, reduction of ordered phase, formation of acicular-ferrite-like lath structure and complexity of crystal orientation. The results calculated based on first principle are further responsible for the reason why Cr and Ni elements contribute to increasing plasticity of Fe-6.5Si-2Cr-12Ni high silicon steel, where 4s-orbital of Cr atom and 3d-orbital of Ni atom are directly involved in bonding. In particular, the activity of the electrons is increased and the intensity of metallic bond is enhanced, which is responsible for enhancing plasticity of Fe-6.5Si-2Cr-12Ni high silicon steel. • The novel Fe-6.5Si-2Cr-12Ni high silicon steel is designed and fabricated. • Fe-6.5Si-2Cr-12Ni high silicon steel possesses high plasticity and strength. • Mechanism for high plasticity of Fe-6.5Si-2Cr-12Ni silicon steel is revealed. [ABSTRACT FROM AUTHOR]

It is shown that the composition of the investigated alloy is nearly identical to the commercially available alloy MP35N (35Co-35Ni-20Cr-10Mo, wt%). However, the thermomechanical treatment of the experimental alloy is quite different from that used for the commercial one which consists of using cold work followed by annealing at temperatures below the recrystallization temperature. Here, depending on the amouunt of cold work, a tremendous hardening effect occurs, due to Suzuki hardening which allows to tune the mechanical properties in a range much larger than obtainable by the strategy used by the High Entropy Community by creating hierarchical microstructures. [ABSTRACT FROM AUTHOR]

Abstract We elucidate here the significance of cold rolling reduction on Lüders band formation and mechanical behavior in cold-rolled intercritically annealed medium-Mn steel. The study indicated that Lüders strain can be decreased by decreasing cold rolling reduction. Moreover, inactive recovery and recrystallization of ferrite consisting of a high dislocation density was responsible for the presence of low Lüders strain. [ABSTRACT FROM AUTHOR]

LZ91 magnesium alloy extruded sheets were subjected to cold rolling. The microstructure and texture evolution were tracked using optical microscopy (OM) and X-ray diffraction (XRD). The α- Mg and β -Li phases were elongated along rolling direction (RD), contributing to the formation of a thin lamellar “sandwich” structure. This “sandwich” structure is favored for glissile dislocation of α- Mg phase during rolling. The α- Mg and β -Li phases are near Burgers orientation relationship, resulting in an unusual RD texture component in (0002) pole figure. [ABSTRACT FROM AUTHOR]

Damages on shear cutting blades were analyzed after 50,000 strokes of trimming on an ultra high-strength steel sheet. Traditional D2 alloy and an advanced one (Cr08H) based on the composition of 1C-8Cr were quenched from 1030 °C, tempered at 180 °C and submitted to the shear cutting test. Cr08H had lower hardness, a smaller volume fraction of M 7 C 3 carbides while it contained a larger volume fraction of retained austenite. And these resulted in more scratches and rounded edges because of degraded resistance to wear and local plastic deformation. In spite of higher impact toughness, Cr08H exhibited inferior resistance to chipping which was the consequence of localized brittle fracture. It could be concluded that this was caused by more transformation of austenite as well as by insufficiently hardened matrix, both of which were attributed to inappropriate conditions of the heat treatment. [ABSTRACT FROM AUTHOR]

This elaboration shows the effect of combined heat treatment and cold working on the structure and utility properties of alloyed copper. As the test material, alloyed copper CuTi4 was employed. The samples were subjected to treatment according to the following schema: 1st variant - supersaturation and ageing, 2nd variant - supersaturation, cold rolling and ageing. The paper presents the results of microstructure, hardness, and abrasion resistance. The analysis of the wipe profile geometry was realized using a Zeiss LSM 5 Exciter confocal microscope. Cold working of the supersaturated solid solution affects significantly its hardness but the cold plastic deformation causes deterioration of the wear resistance of the finally aged CuTi4 alloy. [ABSTRACT FROM AUTHOR]

A two-step strain-induced melt activation (TS-SIMA) process that omits the cold working step of the traditional strain-induced melt activation (SIMA) process is proposed for 6066 Al-Mg-Si alloy to obtain fine, globular, and uniform grains with a short-duration salt bath. The results show that increasing the salt bath temperature and duration leads to a high liquid phase fraction and a high degree of spheroidization. However, an excessive salt bath temperature leads to rapid grain growth and generates melting voids. The initial degree of dynamic recrystallization, which depends on the extrusion ratio, affects the globular grain size. With an increasing extrusion ratio, the dynamic recrystallization becomes more severe and the dynamic recrystallized grain size becomes smaller. It results in the globular grains becomes smaller. The major growth mechanism of globular grains is Ostwald ripening. Furthermore, high-temperature compressibility can be improved by the TS-SIMA process. After a 4 min salt bath at 620 °C, the high-temperature compression ratio become higher than that of a fully annealed alloy. The results show that the proposed TS-SIMA process has great potential. [ABSTRACT FROM AUTHOR]

Cylindrical bars of the advanced nickel based superalloy RR1000 were subjected to swaging to induce approximately 30% cold work. Grain size analysis demonstrated a distinct modification to the microstructure whilst electron back scattered diffraction (EBSD) measurements confirmed the evolution of a relatively strong <111> texture parallel with the longitudinal bar axis. Intragranular strain damage was identified. The effects of the swaging on bulk mechanical properties are illustrated across a range of test temperatures. [ABSTRACT FROM AUTHOR]

The influence of rolling reduction on the microstructural variations in Ti-containing tool steel was investigated. The microstructures, including the prior-austenite grain structure and primary/secondary carbides, were characterized using optical and electron microscopy; the carbides were quantitatively analyzed by small-angle neutron scattering data collected from macro-samples. In parallel with refining the primary carbides, increases in the degree of rolling reduction significantly changes the precipitation kinetics of the secondary MC and M 23 C 6 (M = metallic element) carbides, and thus their mechanical properties, especially the hardness to toughness balance throughout the aging. The improvement of this balance is attributed to the refinement of the prior-austenite grain structure, as well as the retardation of M 23 C 6 precipitation. The reaction kinetics of the precipitation reactions were analyzed by the reduced heat of reaction observed in a calorimetry experiment. [ABSTRACT FROM AUTHOR]

Flow forming is a cold working process that makes it possible to produce high-precision thin-walled rotational symmetric parts leading to increased mechanical properties. The backward flow forming process is numerically modelled with the finite element method (FEM) based on FORGE® NxT 3.2 software, which is used in this work. In order to obtain all elasticity, thermal, physical, and plasticity properties of the AISI 5140 steel material, JmatPro Software is used. The obtained material parameters are defined in FORGE® NxT 3.2 software. For this purpose, microstructural characterization, hardness properties, stress distribution, and strains of samples are figured out. The experimental results are compared with the FEM. The thermomechanical properties and power distributions are carried out in this work. It is well understood that the plastic deformation mechanism plays a significant role in the workpiece temperature during the flow forming process. The hardness and mechanical properties of the AISI 5140 preform increase significantly after flow forming. The grain direction in the longitudinal direction with grain refinement is also observed. The results show that Arbitrary Lagrangian Eulerian (ALE) formulation is a very efficient method for providing very high accurate hardness properties of the workpiece during the flow forming process simulation. The stress distribution, mechanical properties, process temperature, strain rate, dimensional changes, radial, and axial forces are investigated using ALE formulation. In order to validate the FEM results, the same forming process parameters are experimentally performed on annealed AISI 5140 steel tube with a 65% flow forming reduction ratio. Furthermore, axial and radial forces are compared between experimental and simulation. The results show that the final part hardness difference is around 1.5%, and reaction forces error is less than 10% for both radial and axial directions. [ABSTRACT FROM AUTHOR]

A refractory high-entropy alloy HfNbTaTiZr was successfully rolled at room temperature up to 86.4% reduction in thickness (true thickness strain is −2.3). This represents the first successful attempt to cold roll a HEA with a BCC crystal structure. The microstructure and properties of the rolled sheets were determined in the as-rolled condition and after annealing at 800 °C, 1000 °C, and 1200 °C. Cold rolling resulted in extensive grain elongation, formation of deformation bands within the grains, and development of crystallographic textures that depended on the rolling reduction. The 86.4% cold-rolled sheet had true tensile stress of 1295 MPa and tensile ductility of 4.7%. After annealing at 1000 °C and 1200 °C, complete recrystallization of the cold-rolled sheet occurred. After annealing at 1000 °C, the true tensile stress and ductility of the sheet were 1262 MPa and 9.7%, respectively. [ABSTRACT FROM AUTHOR]

In this study, Al2014 alloy refined with Al-5%Ti-1%B master alloy was prepared by strain-induced melt activated (SIMA) process. The main variables of the SIMA process were cold working, holding time and temperature in semi-solid state. Cold working was applied on specimens by upsetting technique to achieve 10%, 20% and 30% height reduction. Cold worked specimens were heat treated in semi-solid state at 585 °C, 595 °C, 605 °C, 615 °C, 625 °C and 635 °C and were kept in these temperatures for different times (20 and 30 min). Observations through optical and scanning electron microscopy were used to study the microstructural evaluation. The results revealed that fine and globular microstructures are obtained by applying 30 % height reduction percentage and heat treating in 625 °C for 30 min. Comparison between refined and unrefined Al2014 alloy after applying SIMA process showed that Al-5%Ti-1%B master alloy has no significant effect on average globule size but makes the final structure more globular. [ABSTRACT FROM AUTHOR]

Effects of substructural dimensions on the mechanical properties of micro-pins produced by an open-die micro-extrusion/forging process were studied. Micro-pins of diameter 0.3 mm were manufactured from copper strips, having different initial grain sizes. Micro-compression tests on the micro-pins revealed no significant size effect, even if the number of grains over the diameter of the micro-pins falls below its critical value. However, relaxation of the as-formed substructure using recovery annealing led to a surprising drop in the flow stress of the micro-pins. This was explained and attributed to the number of subgrains over the diameter of the micro-pins, showing the important role of subgrains rather than grains in determining the mechanical properties. [ABSTRACT FROM AUTHOR]

The design of the WCBB (Water Cooled Breeding Blanket) of the first DEMO reactor foresees a minimum irradiation temperature in the range of 280–300 °C. It is well known that the RAFM (Reduced Activation Ferritic Martensitic) steels suffer a marked DBTT (Ductile to Brittle Transition Temperature) increase under irradiation. This DBTT shift depends both on the DPA (Displacement per Atom) damage and on the Helium production. While the former kind of embrittlement goes to saturation for DPA higher than 20 the latter does not saturate with the dose and results therefore the less manageable issue. Several experimental evidences concerning ODS (Oxide Dispersion Strengthened Steels) RAFM (Reduced Activation Ferritic Martensitic) steels showed that it is possible to improve the resistance to irradiation damage by intra-granular precipitation of Y-Ti oxides and by simultaneously decreasing the grain size. In any case, the multiplication of the grain boundaries is expected to increase the dilution of He on grain surface, delaying the formation of He bubbles on grain boundaries and, therefore, the susceptibility to the He embrittlement. Hereafter we show that it is possible to reduce the grain size by an order of magnitude at the tempering stage, by combining cold working and tempering stages, acting on the tempered martensite. The microstructural observations have been carried out by means of both Scanning and Transmission Electron Microscopy (SEM and TEM). Also the positive effect of grain size reduction on the toughness of the material will be taken into account; the DBTT curves resulting from impact tests on KLST specimens show a peculiar nature, characterized by a smoother transition to the brittle regime, compared to the usual abrupt transitions achieved with the "standard" normalization & tempering treatments on RAFM steels. The outcomes of the microstructural observations, as well as the mechanical characterization (tensile, hardness and impact tests) will be discussed in this paper. [ABSTRACT FROM AUTHOR]

A dual-phase reinforced Cu-0.75 wt% Al 2 O 3 -0.75 wt% TiB 2 composite ingot was prepared by liquid phase in- situ reaction casting method and then processed by hot rolling and cold rolling. The microstructure and property evolution of the composite during processing were investigated, and the strengthening mechanism was determined. Spherical Al 2 O 3 particles with a size of 50～500 nm and irregular polygonal TiB 2 particles with a size of 50 nm～1.5 µm were formed in the Cu matrix. When the cold rolling reduction exceeded 80%, the strengthening particles flowed with the plastic flow of the Cu matrix. The violent shear action between the particles and the Cu matrix made the particle agglomerations separate, which enhanced the uniform dispersion of strengthening particles. For the reduction of 90%, the tensile strength, yield strength, hardness, elongation and electrical conductivity were 477 MPa, 452 MPa, 158 HV, 5.7% and 80.0%IACS respectively. The strengthening mechanisms were dislocation strengthening, dispersion strengthening and subgrain strengthening in descending order. Liquid phase in-situ reaction casting combined with large-deformation rolling is a promising process for the preparation of dual-phase reinforced dispersion strengthened copper matrix composite. • A Cu-0.75 wt% Al 2 O 3 -0.75 wt% TiB 2 composite ingot is prepared by liquid phase in-situ reaction casting method. • The combination of hot working and high cold working can effectively improve the particle distribution of the composite. • The strengthening mechanisms are dislocation, dispersion and grain boundary strengthening in descending order. [ABSTRACT FROM AUTHOR]

We examined the effects of cold working on the corrosion resistances of Ni–30Co–16Cr–15Mo and Ni–16Cr–15Mo in 5.2 M HF acid solution at 100 °C. After cold working, the Ni–30Co–16Cr–15Mo samples exhibited a more significant increase in hardness compared to Ni–16Cr–15Mo as well as a more localised microstructure that contained a greater number of planar slipping bands and mechanical twinning. Both alloys exhibited a decrease in corrosion resistance, with the decrease being much greater in the case of Ni–30Co–16Cr–15Mo. The difference in the corrosion resistances of the alloys was ascribable to the differences in their microstructures. [ABSTRACT FROM AUTHOR]

Effect of addition of rare earth metals on microstructure and properties of copper alloys after casting, after cold working and after heat treatment was studies in this paper. Methodology consisted of microstructure investigations by optical microscopy and scanning electron microscopy. In addition, distribution of alloying elements and electron backscattered diffraction results (EBSD) were presented. The mechanical properties of a wire after tension test and after hardness measurements were described. Electrical conductivity test was performed using Foerster Sigmatest and Thomson bridge. Analysis of the microstructure and mechanical properties of investigated alloys after casting and after metal working showed possibility to produce materials with preferred set of functional properties. [ABSTRACT FROM AUTHOR]

In this investigation, a design of experiments analysis of distortion for a typical manufacturing process involving pre-straightening, cold drawing, and induction hardening of AISI 1045 cylindrical steel bars was carried out. A careful characterization of the material, including residual stress states and geometrical changes, was done for the different manufacturing steps. In order to identify effects and correlations on distortion behavior, the investigated variables included the batch influence, the combined drawing process itself with two different drawing angles and two different polishing and straightening (P.S.) angles, a stress relief treatment which was applied to a part of the samples, and finally induction hardening with two different surface hardening depths. Main and statistically significant effects on the distortion of the induction-hardened samples were found to be in this order: first, the interaction between the drawing angle and batch, then the interaction between drawing angles, and finally drawing angle and induction hardened layer. It was also found that the distortion potentials are transmitted from the drawing process to further manufacturing steps and, consequently, from one production site to the next. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the strain hardening behaviors of a low carbon Nb-microalloyed Si–Mn quenching–partitioning (Q–P) steel were investigated. The microstructures were analyzed by the scanning electron microscope (SEM) and transmission electron microscope (TEM). Mechanical tests were used to evaluate the room temperature tensile properties of the steel. The work hardening behaviors of the tested specimens were analyzed using the Hollomon approach. The results showed that a two-stage work hardening behavior was observed during deformation processes. In the first stage, for the quenched samples, martensite deforms plastically and the hardening exponent decreased. For the air-cooled samples, however, the carbide-free ferrite deforms preferentially, and then, the carbide-free ferrite and martensite co-deform. In the second stage, due to the effect of transformation induced plasticity of retained austenite, the hardening exponent decreased slowly and plateaus were observed in the plots of n i –ε t until fracture. Variations of the work hardening behaviors were related to the martensite and the volume fraction of retained austenite in Q–P steels and the microstructural evolution during partitioning and following cooling process. [Copyright &y& Elsevier]

Abstract: Short ZrO2 fibers (ZrO2(f)) reinforced NiFe2O4 ceramic composites were fabricated by cold pressing process. The phase composition, microstructure, mechanical properties and fiber/matrix interface of the composites were investigated by X-ray diffraction, scanning electron microscopy and mechanical testing machines. ZrO2(f) show good thermodynamic and chemical compatibility with NiFe2O4 ceramic matrix and effectively enhanced the mechanical properties. The toughening mechanisms are fiber bridging, interfacial debonding, fiber pullout, phase transformation and the matrix constraint effect. By incorporation of 3wt% fibers with the average length of 5∼6mm, the bending strength and fracture toughness of the composites reached 88.92MPa and 4.62MPam1/2, respectively, while the strength conservation ratio after thermal shock increased from 48.85% to 75.86%. The weak interface bonding built up between ZrO2(f) and NiFe2O4 facilitates the reinforcing effects of the fibers to operate. [Copyright &y& Elsevier]

Abstract: In this study, variations of hardness, electrical conductivity, strength, elongation and microstructure of the Cu–13.5%Mn–4%Ni–1.2%Ti alloy were investigated during aging, cold-working and subsequent aging. X-ray diffraction (XRD), transmission electron microscopy and scanning electron microscopy methods were used to evaluate the microstructure of the alloy. Tensile, hardness and electrical conductivity measurements were also used for investigating the effects of processing parameters on the characteristic of the alloy. Hardness value of 190HV and strength of 644MPa were obtained after aging the as-cast alloy for 4h at the temperature of 500°C. The maximum hardness and strength increased up to 253HV and 816MPa, respectively, after aging 60% cold-worked samples for 1h at the temperature of 500°C. The dominant strengthening mechanism during aging was attributed to the precipitation of Cu4Ti phase. Formation of the β-Cu3Ti phase during aging at the temperature of 500°C was another reason of strengthening. As a result of aging, electrical conductivity of both as-cast and cold-worked alloys was improved. The maximum conductivity of 29.7% IACS was attained after aging the as-cast material at the temperature of 500°C for 4h. [Copyright &y& Elsevier]

Abstract: Thermal stability of the nanocrystalline Ti–10V–2Fe–3Al alloy produced by cold-forging and corresponding hardness variations were investigated. When the annealing temperature was lower than 400°C, the primary features were the decline of lattice defect density and the increase of lattice ordering level in the vicinity of grain boundaries, named as grain boundary relaxation. The nanocrystalline grains grew slowly. In comparison, when the annealing temperature was higher than 400°C, the decomposition of the deformation-induced α″ martensites and the subsequent rapid grain growth were observed. Vickers hardness measurement shows an initial hardening followed by a softening with the increase of annealing temperature. The hardening peak appeared at 400°C. The critical grain growth temperature, i.e., T cgg, in the nanocrytalline Ti–10V–2Fe–3Al alloy, was slightly lower than those in other nanocrystalline alloys. That could be attributed to the martensitic decomposition-induced grain growth in this alloy. [Copyright &y& Elsevier]