Temperature Range Of Recrystallization Research Articles

Recrystallization kinetics of larger yttria particle dispersion tungsten alloy warm rolled to 50% thickness reduction

Tungsten-based materials are considered one of the candidate materials for the key components (such as the first wall and diverter) of future thermonuclear fusion reactors because of their excellent properties. At high operation temperatures, restoration processes such as recovery, recrystallization and grain growth will unavoidably embrittle ductile tungsten achieved by rolling. Dispersed second-phase particles will affect the recrystallization behavior. The thermal stability of a yttria dispersion-strengthened tungsten plate warm-rolled to 50% thickness reduction is investigated. Isochronous annealing is used to predict its recrystallization temperature range and isothermal annealing is used to study its recrystallization kinetics. The tungsten alloy in the present study has a faster recrystallization kinetics and a smaller activation energy compared to that of W-2 vol% Y2O3 alloy with small Y2O3 particles, indicating that the larger Y2O3 particles have little effect on impeding grain boundaries during recrystallization.

Correlation of imposed mechanical energy with ductility-dip cracking in a highly restrained weld of Alloy 52

Ductility-dip cracking (DDC) is a complex weldability issue affecting industries using high-chromium nickel-based filler metals required for superior resistance to stress corrosion cracking, most notably in the nuclear power generation industry. DDC is a solid-state cracking mechanism which occurs in the temperature range of 0.5–0.8TM and is primarily attributed to grain boundary sliding. Above 0.8TM, recrystallization inhibits initiation of DDC and has been observed to arrest propagation. A computational model of thermo-mechanical behavior in a narrow groove multipass weld of DDC-susceptible filler metal was developed in past research and revisited here to calculate and analyze the mechanical energy imposed during the welding process. It was found that areas in the weld with high imposed mechanical energy (IME) in the recrystallization temperature range coincided with regions devoid of cracking but rich in evidence of recrystallization. Weld areas with low IME in the recrystallization temperature range but with higher IME in lower temperature ranges coincided with regions where DDC is observed. This agrees with past research suggesting recrystallization acts to prevent cracking. This paper presents an integrated computational materials engineering (ICME) approach that includes the IME to better predict and quantify DDC susceptibility in multipass welds.

Optimization of Thermal and Deformation Effect during Plastic Deformation and Thermal Treatment of Hot Rolled Heavy Wall Pipes Made of Medium Carbon Martensitic Steel

The method of stress relaxation in isothermal aging after deformation is employed to determine recrystallization temperature range (Trec) for 38HN3MFA (35HN3MFA) steel grade. The paper shows that billet final deformation at the temperature lower than Trec followed by annealing including heating and aging at Trec enables austenite grain refinement.

Microstructure Transformation of Mg-1.6Gd during Hot Rolled at High Deformation Ratio

Mg-1.6Gd alloy was prepared by hot rolling to produce a potentially degradable implant materials. Microstructural transformation during hot rolling was observed and correlated to mechanical properties. The objective of this study was to examine the constituents of the microstructure such as grain size, phases which are contributed to mechanical properties. Hot rolled Mg-1.6Gd alloy was performed at a temperature range of recrystallization (400-550 °C) with a speed of 10 mm/min and reduction of 95%. The hot rolled was employed by two methods: unidirectional rolling (UR) and cross rolling (CR). The results show that both of the hot rolling techniques reveal refine microstructure with the grain size range of 50-130 µm. The number of lamellar in every grain were shown on the UR, while for the CR resulted in many precipitates, especially at the highest temperature hot rolling. The hot rolled sample of 95% reduction had the relatively smaller of the grain size than the hot rolled sample of 30% reduction (200 µm).

Effect of severe reduction on mechanical properties during hot rolling of Mg–1.6Gd alloys

The mechanical properties of severely hot rolled Mg–1.6Gd (wt.%) alloys, such as hardness, ultimate strength, yield strength and ductility have been studied in the context of biodegradable implant materials. Unidirectional rolling (UR) and cross rolling (CR)were applied to prepare Mg–1.6Gd alloy ingots. In general, the mechanical properties of the alloy greatly improved after hot rolling due to a refinement of the microstructures. The relationship between the microstructure and mechanical properties is discussed in detail. Hot rolled samples were prepared in the temperature range of recrystallization(400–550 °C)with a speed of 10 mm min−1 and a total reduction of 95% at 23.75% per pass, with an aim to characterize mechanical properties of the Mg–1.6Gd alloy such as hardness, ultimate strength yield strength and ductility. Tension and hardness testing were carried out and theVickers hardness values for the hot rolled samples were about 40–50 HV. The Vickers hardness increased with increasing hot rolling temperature. The maximum tensile strength and yield strength observed forUR samples were 197 MPa and 157 MPa, respectively and for CR samples, the values were 164 MPa and 107 MPa, respectively. Further, the maximum elongation for UR samples was 26% and, 17% for CR samples. Samples hot rolled with 95% reduction showed a higher ultimate tensile strength and ultimate yield strength than samples hot rolled with 30% reduction. The maximum elongation also differed between the two rates of reduction, where 95% reduction yielded an elongation of 26%, while a 30% reduction resulted in a maximum of 15%. The mechanical properties reported in this work highlight the benefits of Mg–1.6Gd as material for use in degradable implants.

Determination of the temperature range of recrystallization based on structural studies of an austenitic high-nitrogen Cr–Mn–Mo steel

The effect of thermoplastic treatment, which includes cold plastic deformation by rolling, on the microstructure of a high-nitrogen 07Kh16AG13M3 steel has been studied. The temperature range of recrystallization is determined by three methods. An equation is proposed for calculating the melting temperature of the high-nitrogen austenitic steel

Effect of Thermo-Mechanical Treatment on Mechanical Properties of AlCuMg Alloys

Technology development and new grades of alloys creation put before construction materials the number of requirements in range of durability and reliability of created constructions. Receivers expect materials with high strength properties, low production cost of the finished product, availability, corrosion resistance and low specific gravity. So the specific needs of customers mean that studies are constantly associated with the exploration of new materials and technologies that could meet made requirements [1,2,. In large scale this demand is met through the use of non-ferrous metals and their alloys. Selection of appropriate manufacturing techniques and the use of heat treatment procedures allow to obtain materials with better mechanical properties. Here the leading role has the aluminium and its alloys. Due to specific mechanical properties aluminium based materials are used in almost each field of industry. In aircraft industry they are used for the manufacture of fuselage elements in automobile industry the light alloys are used to make cylinder blocks, and other elements of internal combustion engines. In the construction industry they are used to manufacture windows and doors, as well as beautiful self-supporting lightweight facades. While the aluminium alloy products such as films or cans are also used in the food industry. The combination of physico-chemical and mechanical properties of aluminium alloys makes them the optimal solution for innovative design, thanks to them engineers can provide high strength associated with very low gravity. This allows to minimize the costs of subsequent use of the product, and while achieving good strength parameters. As part of this work the analysis of strain rate and temperature impact on mechanical properties of the tested alloy will be carried out. The experimental studies conducted in the temperature range of recrystallization (test temperature: 400°C, 450°C, 480°C, 500°C) using two strain rates 1 s-1and 0,1 s-1. This paper present the analysis of the application of high-temperature deformation changes in structure mainly caused by the dynamic recrystallization processes, which determine the optimal parameters of AlCuMg deformation process [. The proposed methodology of the research work made it possible to determine the effect of temperature-velocity parameters to changes in mechanical properties (inter alia: microhardness measurements) and changes in the structure of the material, which are closely related to the level achieved in mechanical properties.

Research of 50Mn2V continuous casting slab transverse cracking during its retarded cooling process

In this paper, the reason of 50Mn2V transverse cracking is studied by optical metallographic, SEM and in situ analysis system. Results show that the pearlite is surrounded by the net-like pro-eutectoid ferrite which locates at the former austenite grain boundary, the hydrogen content (ca. 2×10−4wt%) exceeds the critical solubility in room temperature structure, divers types and sizes inclusions (10–100μm), plenty of fissures (2–50μm) and classical cleavage fracture surface are obviously observed, meanwhile, a great degree of elements segregation (P, S, V, Ni, Cr correspond to 1.757, 1.674, 1.729, 1.475, 1.195, respectively) and a poorly 0.9283 integral density exist in this blank, high temperature thermoplastic experiment shows the ductility trough existing until the dynamic re-crystallization temperature range. From the above, internal gas pressure should be the dominant factor that leads the transverse embrittlement, while internal stresses, element segregation and defects play an ancillary role.

Shot Peening Characteristics of Cold-Rolled Mo Sheet

The commercial pure Mo sheet was shot peened to increase high-temperature mechanical and thermal resistance. Shot peenining was conducted on the surface of cold-rolled Mo sheet with 0.4MPa of shot pressure. The hardness of bcc Mo sheet was increased with increase of shot peening time. Surface hardenss is gradually increased to 120s at the 0.4MPa pressure, but the profiles become almost flat at the prolonged time. The grains were deformed and work hardened in the surface layer. The surface roughness was also increased with peening time. The grain size of shot-peened Mo sheet was smaller than that of cold-rolled Mo sheet in the all recrystallization temperature range. The reason for this could be a larger density of nucleation sites caused by the higher surface deformation of shot-peened Mo sheet. Mo2C carbide phase was analyzed on the surface of recrystallized Mo sheet at the secondary recrystallization temperature range. It was considered that molybdenum carbide was formed due to the evaporation of graphite heating element in the hot-zone furnace. From this study, shot peening of Mo sheet could be a good cold work hardening method to improve high-temperature mechanical and thermal resistance properties.

Grain growth and recrystallization of nanocrystalline Al3Ti prepared by mechanical alloying

The grain sizes and lattice strains during mechanical alloying of Ti-75 at.% Al powder mixtures were studied using X-ray diffraction methods. Nanocrystalline L12-Al3Ti was obtained after a certain time period of ball milling. Minimum grain sizes of 17 nm for Al and 28 nm for Ti have been determined using XRD. During subsequent thermal annealing processing, an obvious recrystallization resulting in significant reduction of grain size was observed. The recrystallization in nanocrystalline Al3Ti was affected by both the temperature and the degree of order. The incubation period for recrystallization at 400°C was about 6 hours while those at 510 and 700°C were about 2 hours. The completion time of recrystallization in Al3Ti at 400 and 700°C was about 15 hours and 8 hours at 510°C. It is clear that the recrystallization at 700°C was retarded as a result of the higher degree of order structure which limited the mobility of the boundaries. Phase transformation occurring within the recrystallization temperature range was observed to have little influence on the recrystallization itself. However, transformation products do have significant effects on it which is originated from the degree of order in the products. The recrystallization in this alloy system provides an excellent means to maintain the nanocrystalline microstructure during the necessary consolidation thermal cycle by decreasing the processing temperature and increasing the hold time considerably.

Effect of Sb, Sn and Pb on the recrystallization of bismuth

High purity bismuth and BiSb, BiSn and BiPb solid solutions were deformed by uniaxial compression and subsequently annealed for one hour. The annealing temperature was varied and changes in electrical resistivity, hardness and microstructure were followed. The decreases in resistivity and hardness after a single annealing are attributed to recrystallization, a hypothesis which is confirmed by microstructural observations. The recrystallization temperature, temperature range of recrystallization and estimated energy released increase with solute content and type (in the order Sb, Sn, Pb). The greater the deviation from the Hume-Rothery rules for substitutional solutions, the greater is the effect which solute addition appears to have on the recrystallization process.

Correction of the coarse-grain structure of alloyed tool steels

1. The recrystallization of austenite is the basic process in the correction of coarse-grained structures. We found a dependence of the austenite recrystallization temperature range on the heating rate for forged cylinders of steels 9Kh2, 9Kh2MF, and 9Kh2SVF. 2. The peak and subsequent drop on the dilatometric curves and the curves showing the variation of the amount of residual austenite with the quenching temperature are due to the recrystallization of austenite. 3. We found inherited vestiges of overheating in repeated heating of the steel. The austenite formed during heating of previously overheated steel contains more carbon and alloying elements than the austenite in the steel not overheated. 4. To correct the coarse-grained structure in forgings we recommend that steels 9Kh2, 9Kh2MF and 9Kh2SVF be heated to temperatures at the upper limit of the austenite recrystallization range.