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A new technology has been developed for restoring worn cast iron parts using electric arc surfacing. This technique uniquely combines the simultaneous introduction of filler materials, both as seamless wire and powder alloys, directly into the weld pool. Additionally, oxygen is supplied to the surfacing zone to decarburize the weld pool. The powder alloys used are enriched with graphitizers and carbide-forming elements to protect the melt during the crystallization process. Research has found that the connection zone between the original material and the added layer consistently features a transition layer, regardless of the specific gases and powder materials used. Notably, the use of NPCh‑3 powder, together with the supply of oxygen and carbon dioxide into the weld pool is 2.0–2.7 times thinner than those produced with either PG-12N-01 or PG-10N-04 powders. This method significantly enhances the quality of the deposited layer by increasing the proportion of finely dispersed complex carbides, obtaining an equilibrium structure of fine-plate pearlite with finely dispersed graphite deposits. This results in minimal porosity and the elimination of microcracks, while also reducing cast iron microhardness in the heat-affected zone by 2.1 times. A technology has been developed for restoring cast iron parts through electric arc gas-electric surfacing. This approach has been tested in industrial settings, demonstrating its ability to reduce metal scattering, porosity, and hardness of the deposited layer and the transition zone,. Furthermore, it significantly lowers the likelihood of crack formation, all while minimizing the expenditure on. [ABSTRACT FROM AUTHOR]

Lab grown single crystal diamonds (SCDs) offer unrivalled hardness, a wide range of optical transparency, and supremely high thermal conductivity reliable materials to be a part of devices run at high frequency, temperature, and power. Effective synthesis techniques are essential in enhancing the potential applications of high-quality SCDs. This study aims to decrease the thermal contact resistance between diamond seeds and the molybdenum holder by utilizing welding material. Quality of grown diamond substrates (plates) were assessed by analysing optical properties through Raman, UV-Vis, and FT-IR spectroscopic methods. The findings revealed that the grown single-crystal diamonds have excellent transmittance (>70%) and absorption at 270 nm. Calculations also showed an average absorption coefficient of 1.1 cm−1, indicating the high quality of the grown SCDs with nitrogen impurities below 10 ppm. The absorption observed in the FTIR spectra, ranging from 1600 cm−1 to 2700 cm−1 with a peak at 2354.13 cm−1, is referred to as the “two phonon region,” which is a distinctive feature of the diamond phase.

When manufacturing the welded joints of components made of metal–ceramic composites of the Al-Si/SiC type, we encounter significant difficulties. This is related to the presence of a ceramic phase in the aluminium alloy matrix. The interaction between the molten metal matrix and the ceramic particles in the weld pool influences a complex of physicochemical phenomena resulting in, among other things, the structure of the welded joint. This is particularly true of the effect of the distribution of ceramic particles and their influence on the crystallisation process in the weld pool. An important issue is the influence of the reinforcing particles on the susceptibility of the aluminium matrix to both hot and cold cracking. The scope of the research included the development of the chemical composition of an additive material for the TIG welding of aluminium–ceramic composites. This material was made in the form of so-called sticks, cast from alloys containing elements such as magnesium, scandium or zirconium in addition to aluminium. The appropriate composition of the mass content of the individual components was intended to change the crystallisation mode of the weld pool and to obtain strengthening precipitates. The most favourable structure was obtained in the case of a modification of the AlMg5 alloy by the addition of scandium. Minor dispersions of Al3Sc became the nucleation pads of fine grains, which improved the mechanical properties of the alloy. Also, in the case of the addition of zirconium, the crystallisation shifted from dendritic to fine-grain growth. In this paper, the basic strength properties of the developed materials were tested and the most favourable chemical compositions of the filling materials were selected. [ABSTRACT FROM AUTHOR]

When manufacturing the welded joints of components made of metal–ceramic composites of the Al-Si/SiC type, we encounter significant difficulties. This is related to the presence of a ceramic phase in the aluminium alloy matrix. The interaction between the molten metal matrix and the ceramic particles in the weld pool influences a complex of physicochemical phenomena resulting in, among other things, the structure of the welded joint. This is particularly true of the effect of the distribution of ceramic particles and their influence on the crystallisation process in the weld pool. An important issue is the influence of the reinforcing particles on the susceptibility of the aluminium matrix to both hot and cold cracking. The scope of the research included the development of the chemical composition of an additive material for the TIG welding of aluminium–ceramic composites. This material was made in the form of so-called sticks, cast from alloys containing elements such as magnesium, scandium or zirconium in addition to aluminium. The appropriate composition of the mass content of the individual components was intended to change the crystallisation mode of the weld pool and to obtain strengthening precipitates. The most favourable structure was obtained in the case of a modification of the AlMg5 alloy by the addition of scandium. Minor dispersions of Al3Sc became the nucleation pads of fine grains, which improved the mechanical properties of the alloy. Also, in the case of the addition of zirconium, the crystallisation shifted from dendritic to fine-grain growth. In this paper, the basic strength properties of the developed materials were tested and the most favourable chemical compositions of the filling materials were selected.

Purpose – In view of the difficulty in determining the key parameters d in the Corten-Dolan model, based on the introduction of small loads, damage degrees and stress states to the Corten-Dolan model and the existing improved model, the sequential effects of the adjacent two-stage load were further considered. Design/methodology/approach – Two improved Corten-Dolan models were established on the basis of modifying the parameter d by two different methods, namely, increasing stress ratio coefficient as well as considering the effects of loading sequence and damage degree as independent influencing factors respectively. According to the test data of the welded joints of common materials (standard 45 steel), alloy materials (standard 16Mn steel) and Q235B steel, the validity and feasibility of the above two improved models for fatigue life prediction were verified. Findings – Results show that, compared with the traditional Miner model and the existing Corten-Dolan improved model, the two improved models have higher prediction accuracy in the fatigue life prediction of welding materials whether under two-stage load or multi-stage load. Originality/value – Because the mathematical expressions of the models are relatively simple and need no multi-layer iterative calculation, it is convenient to predict the fatigue life of welded structure in practical engineering.

The welding materials and processes of fusion welding joint for TA1-X80 explosive composite plate were designed by corresponding welding experiment. Based on the microstructure, composition and properties of the welded joints, a good welding material and process as transition layer for welding titanium-steel composite plate was obtained. The results show that Y-type groove and double-layer transition for metallurgical connection of titanium-steel composite plate are effective. The double-layer consists of nearly titanium layer of Ti-Ni-Al alloy and nearly steel layer of Ni-Cr-Fe alloy. The weld microstructure is changed from coarse equiaxed grain in the titanium layer to fine equiaxed grain or dendrite in the transition layer, and finally is interlaced with the structure of steel. The tensile and yield strength of the welded joint are 501.1MPa and 373.0MPa respectively, which reach the equal match. But the plasticity and toughness are slightly insufficient, which can be improved subsequently by reducing the thickness of the transition layer and adjusting the elements for refining grain size.

The results of research of basic and welding materials are adduced. The rotor of a slow-moving turbine for HCNP manufactured using the developed complex technology is developed and put into operation. New welding materials, argon arc welding of root seams and automatic welding under the flux of the main joints in the slotted section are recommended; a thermal cycle for manufacturing welded rotors, including heating during welding, thermal waste and final heat treatment is indicated. [ABSTRACT FROM AUTHOR]

Featured Application: The main purpose of this study is to present a damage constitutive model of welded joints in steel structures, which can provide a basis for the precise design of steel structure joints. It can be popularized and applied in steel structure building, hydraulic steel structure pump house, dike and so on in field of civil engineering and hydraulic engineering. It also can be used for reference in the field of mechanical manufacturing. The weld form of intersecting joints in a steel tubular truss structure changes with the various intersecting curves. As the key role of joints in energy dissipation and seismic resistance, the weld is easy to damage, as a result the constitutive behavior of the weld is different from that of the base metal. In order to define the cumulative damage characteristic and study the constitutive behavior of welded metal with the influence of damage accumulation, low-cycle fatigue tests were carried out to evaluate overall response characteristics and to quantify variation of cyclic stress amplitude, unloading stiffness and energy dissipation capacity. The results show that the cyclic softening behavior of welding materials is apparent, however, the steel shows hardening behavior with the increase of cyclic cycles, while the cyclic stress amplitude, unloading stiffness, and energy dissipation capacity of the welding materials degenerate gradually. Based on the Ramberg–Osgood model and introducing the damage variable D, a hysteretic model of welding material with the effect of damage accumulation was established, including an initial loading curve, cyclic stress-strain curve, and hysteretic curve model. Further, the evolution equation of D was also built. The parameters reflecting the damage degradation were fitted by the test data, and the simulation results of the model were proved to be in good agreement with the test results. [ABSTRACT FROM AUTHOR]

The weld form of intersecting joints in a steel tubular truss structure changes with the various intersecting curves. As the key role of joints in energy dissipation and seismic resistance, the weld is easy to damage, as a result the constitutive behavior of the weld is different from that of the base metal. In order to define the cumulative damage characteristic and study the constitutive behavior of welded metal with the influence of damage accumulation, low-cycle fatigue tests were carried out to evaluate overall response characteristics and to quantify variation of cyclic stress amplitude, unloading stiffness and energy dissipation capacity. The results show that the cyclic softening behavior of welding materials is apparent, however, the steel shows hardening behavior with the increase of cyclic cycles, while the cyclic stress amplitude, unloading stiffness, and energy dissipation capacity of the welding materials degenerate gradually. Based on the Ramberg–Osgood model and introducing the damage variable D, a hysteretic model of welding material with the effect of damage accumulation was established, including an initial loading curve, cyclic stress-strain curve, and hysteretic curve model. Further, the evolution equation of D was also built. The parameters reflecting the damage degradation were fitted by the test data, and the simulation results of the model were proved to be in good agreement with the test results.

The first layer of the deposit on the edges of low-alloy steels in producing welded joints with 08Cr18Ni10Ti steel is made using materials based on 02Cr24Ni13 composition (TsL-25L electrodes, welding wire SV-02Cr24Ni13) producing the deposited metal with a reduced carbon content and the required content of the ferritic phase (2–5%). Welding with these materials results in the required parameters of technological properties in welding and efficiency of the austenitic–ferritic deposited metal: resistance to solidification cracking; preventing the formation of a structure containing very hard brittle compounds; preventing the formation of the sigma phase and, correspondingly, embrittlement in tempering; the mechanical properties and fatigue strength satisfy the requirements of PNAE G-7-002–86. Technical documents for the production of these welding materials have been compiled. [ABSTRACT FROM AUTHOR]

The room temperature creep behavior of X80 pipeline has attracted increasing attention because it is considered to be a reasonable cause of failure in pipeline steel. In order to investigate the influence of loading stress, loading rate and creep-fatigue interaction on the room temperature creep, three types of room temperature creep experiments of base metal and welding specimens were carried out when loading stress changes from 0.85 σ s to 1.05 σ s (σ s is the yield strength of material) and loading rates changes from 0.63 kN/min to 1.23 kN/min. The results of experiments show that the room temperature creep of X80 pipeline steel strongly depends on the loading stress and loading rate, but no creep was measured when loading stress is lower than 0.85 σ s. One hour fatigue load has no effect on the creep, and the second creep strain is much smaller than the first creep strain. The room temperature creep and dislocation creep mechanisms of the base metal and welding zones are revealed. In addition, the nonlinear creep expression of primary and second stages related to loading stress at room temperature are obtained to evaluate the base metal and welding specimens based on Norton power function theory. The results obtained from the study will provide a reference to the research of room temperature creep of the X80 pipeline steel and corresponding welding zone. • Creep behaviors of base metal and welding materials of X80 pipeline steel are discussed. • Effects of loading rate and creep-fatigue interaction on creep are analyzed. • Room temperature creep strongly depends on the retaining stress and loading rate. • Nonlinear fitting equations of room temperature creep are obtained based on Norton model. • Creep mechanism can be explained by movable dislocation. [ABSTRACT FROM AUTHOR]

The doping mixture CeO2 + SnO2 + Ag has been added to YBa2Cu3Or-γ(Y123). The basic idea was to combine the greatly enhanced superconducting properties of CeO2 + SnO2 doped Y123 and the silver faculty to decrease the melting peritectic decomposition temperature of Y123, in order to use this material as a welding material for CeO2 + SnO2 doped Y123 textured blocks. Consequently, different physico-chemical properties of this composition have been studied. It is shown that silver decreases the decomposition temperature of CeO2 + SnO2 doped Y123 from at least 30°C and that, for an addition of 5 wt%Ag, the critical current densities under all magnetic fields are totally similar to the CeO2 + SnO2 doped Y123 ones. Hence, this composition appears really promising as a candidate for realizing high quality welds of CeO2 + SnO2 doped Y123 blocks. [ABSTRACT FROM AUTHOR]