An Investigation of Friction Coefficient on Microstructure and Texture Evolution of Interstitial-Free Steel during Warm Rolling and Subsequent Annealing

A Ti bearing interstitial-free steel was finishing rolled in the ferrite region with and without lubrication and microstructures, mechanical properties and textures evolution during warm rolling and subsequent annealing were investigated by OM, SEM, tensile test and ODF. The results show that the surface microstructure of the as-rolled specimen without lubrication is composed of dense shear bands, while the microstructures of the central layer of the as-rolled specimen without lubrication and the whole cross section of the as-rolled specimen with lubrication are elongated ferrite. Short-time annealing can make the non-lubricated rolling sample recrystallize, but the lubricated rolling sample cannot. After complete recrystallization, the microstructure of the surface layer of the as-annealed specimen without lubrication is finer than that of the center layer of the as-annealed specimen without lubrication and the whole section of the as-annealed specimen with lubrication. The mechanical properties of as-annealed sample without lubrication change significantly in the initial annealing stage, while that of as-annealed sample with lubrication remain unchanged until the end stage of annealing. The surface layers of the as-rolled samples have strong Goss component and weak γ fibre components, while the central layers have strong γ fibre components and moderate rotated cubic components. As annealing proceeds, the Goss components of the surface layer decrease and the γ fibre components increase. The rotated cubic components in the central layer are gradually transformed into γ texture.

The Effects of Recrystallization on Strength and Impact Toughness of Cold-Worked High-Mn Austenitic Steels

High-Mn austenitic steels have been recently developed for a storage or transportation application of liquefied natural gas (LNG) in cryogenic fields. Since the structural materials are subjected to extremely low temperature, it requires excellent mechanical properties such as high toughness strength. In case of high-Mn steels, twinning deformation during the cold-working process is known to increase strength yet may cause embrittlement of heavy deformed twin and anisotropic properties. In this study, a recrystallization process through appropriate annealing heat treatments after cold-working was applied to improve the impact toughness for high-Mn austenitic steels. Microstructure and mechanical properties were performed to evaluate the influence of cold-worked and annealed high-Mn austenitic steels. Mechanical properties, such as strength and impact toughness, were investigated by tensile and Charpy impact tests. The relationship between strength and impact toughness was determined by microstructure analysis such as the degree of recrystallization and grain refinement. Consequently, both elongation and toughness were significantly increased after cold-working and subsequent annealing at 1000 °C as compared to the as-received (hot-rolled) specimen. The cold-worked high-Mn steel was completely recrystallized at 1000 °C and showed a homogeneous micro-structure with high-angle grain boundaries.

Microstructure and Mechanical Properties of Multi-Pass Warm Rolled Ti-6Al-4V Alloy of Different Microstructures

In this investigation three kinds of raw microstructure Ti-6Al-4V alloys were studied using two directional rolling on a conventional rolling mill. The effect of deformation on microstructure and mechanical properties has been attempted. Microstructural observation indicated that the size of the lamellar/equiaxed α grain was sharply decreased to submicro after multi-pass warm rolling. Tensile test results showed that the multi-pass warm rolling process was found to have a remarkable strengthening effect. The ultimate tensile strength and yield stress were increased by more than 10% and 25% respectively compared with unidirection rolled specimen, and the elongation has been increased by more than one times, and the maximum is up to 1.58 times. Meanwhile, the difference of the strength and elongation between in rolling direction and in transverse direction has been greatly reduced.

Microstructural evolution and mechanical properties response of the ZT40 alloy with hot rolling

The Zr-40Ti-4.5Al-4.2V (ZT40) alloy is one of new developed Zirconium alloys with high mechanical properties and great potential for application. The investigation about effects of plastic deformation on microstructure and mechanical properties can promote practical applications of the new high performance ZrTi based alloys. The microstructural evolution and mechanical properties of the ZT40 alloy suffered hot rolling with thickness reduction from 30% to 60% at 775 °C are investigated in this work. Results show that the phase constitution changes from (α + β) to (β + fcc) while the original specimen underwent hot rolling and subsequent water quenching. The β phase in hot rolled specimen adopts preferred orientation form (200) and (211) planes to only (200) plane while the rolling reduction increases from 30% to 60%. Furthermore, no obvious preferred orientation can be detected in specimen with reductions of 60%. Micrographs analysis shows that the dynamic recrystallization occurs in hot rolled specimens. Volume fraction of the DRX grains is approximately 8% in 30% reduction specimen and increases with the increasing of rolling reduction. Nearly full recrystallization is observed in the specimen with reductions of 60%. Hardness test shows that the HV of hot rolled specimen decreases from 384 HV to 329 HV as the increasing of reduction from 30% to 60%. The mechanisms of microstructural evolution and variation of hardness are also discussed. The finding should contribute to understand microstructural evolution, to adjust mechanical properties and to promote practical applications of Zirconium alloys.

Influence of Asymmetric Hot Rolling on Microstructures of Vessel Steel

The symmetric/asymmetric hot rolling experiments were carried out to investigate the effect of shear deformation on microstructure of vessel steel by using electron back-scattered diffraction (EBSD) and field emission transmission electron microscope. The study shows that gradient distribution grain size through the thickness is formed in asymmetric rolled specimen. The grain size in surface is smaller than the one in center. The grain distribution is homogeneous in symmetric rolled specimen. The grain in asymmetric rolled specimen is smaller than the one in symmetric rolled specimen in the same thickness position. The precipitate particles morphology are random precipitate and interphase precipitate in symmetric and asymmetric rolled specimen. The precipitate particles tend to nucleate and grow in the grain in symmetric rolled specimen. The precipitate particles located in grain boundary are observed in asymmetric rolled specimen.

Effect of Deformation on the Corrosion Behavior of Chromium Bronze

The service life of material is much related with its corrosion resistance. Thus, the investigation on corrosion behavior is important for the better use of material. In this paper, the corrosion behavior of deformed chromium bronze experienced different processing was investigated in NaCl environment using electrochemical measurements and mass-loss tests. It has showed that the potentiodynamic polarization curves of cold rolled specimen coincide with that of cold worked specimen in two concentration of NaCl solution. The last cold working has little effect on the electrochemical behavior of cold rolled chromium bronze.The NaCl fog experiment showed that the corrosion resistance of cold rolled specimen is slightly better than that of cold worked specimen, and the mass-loss for two kinds of specimen are similar in the initial stage but the gap is increasing with corrosion time. The corrosion scales on the surface of specimen, accumulated in the form of island produced in the NaCl fog experiment , has little hindered effect on corrosion behavior.

Effect of Bell-Type Annealing Process on Properties of SPCC Cold-Rolled Steel Sheet

This study simulated Bell-type annealing technology under laboratory conditions, and researched the effect of annealing time on the mechanical properties of SPCC cold-rolled steel sheet. The results indicate that the yield strength decreased with the extending of time; the plastic strain increases with the elongation of annealing time till a given time, and then decreased with the time extending; the cold-rolled specimen brittle fractured in tension while the annealed specimen shear fractured. Key words: microstructure mechanical properties Bell-type annealing SPCC cold-rolled steel sheet