scholarly journals Effect of Hot Rolling on Microstructural Evolution and Wear Behaviors of G20CrNi2MoA Bearing Steel

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 957
Author(s):  
Guanghua Zhou ◽  
Wenting Wei ◽  
Qinglong Liu
Keyword(s):  
Grain Boundaries ◽  
Hot Rolling ◽  
Carbon Concentration ◽  
Hot Deformation ◽  
Volume Fraction ◽  
Large Angle ◽  
Bearing Steel ◽  
Rolling Reduction ◽  
Effect Of Hot Rolling ◽  
Quenching And Tempering

Hot rolling can improve the mechanical properties after heat treatment by improving the microstructure. The effect of hot rolling (HR) deformation on the microstructural transformation of G20CrNi2MoA bearing steel in the subsequent CQT (carburizing-quenching and tempering) and RQT (reheating-quenching and tempering) processes was studied. The results indicate that the austenite grain size decreased by 20% after 45% hot rolling reduction, and the number of large-angle grain boundaries increased due to the recovery and recrystallization induced by hot deformation. The refinement effect of hot deformation on austenite grains was retained after dual austenitizing, and the large-angle grain boundaries and massive dislocation in the grains caused by hot deformation promoted the diffusion of carbon atoms during carburization, resulting in a higher surface carbon concentration. The refined grains and higher carbon concentration affected the volume fraction and size of undissolved carbides in RQT specimens. When the initial hot rolling reduction reached 45%, the average particle size of carbides decreased by 40%, and the area volume fraction increased by 37%. The Vickers hardness increased, but the friction coefficient and wear rate were significantly reduced with the increase in the initial hot rolling reduction. The main reasons for the improved wear resistance were fine grains, superior carbide distribution and high hardness.

Hot Deformation Behavior and Microstructural Evolution of Mg-Nd-Zn-Zr Magnesium Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 320-326 ◽  
Author(s):  
Wen Xiang Wu ◽  
Li Jin ◽  
Jie Dong ◽  
Zhen Yan Zhang ◽  
Wen Jiang Ding
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Hot Deformation ◽  
Fine Particles ◽  
Volume Fraction ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Average Size

The hot deformation behaviors and microstructural evolution of Mg-3.0Nd-0.2Zn-0.4Zr (wt. %, NZ30K) alloy were investigated by means of the isothermal hot compression tests at temperatures of 350-500 °C with strain rates of 0.001, 0.01, 0.1 and 1s-1. The results showed that the flow stress increased to a peak and then decreased which showed a dynamic flow softening. The flow stress behavior was described by the hyperbolic sine constitutive equation with an average activation energy of 193.8 kJ/mol. The average size of dynamically recrystallized grains of hot deformed NZ30K alloy was reduced by increasing the strain rate and/or decreasing the deformation temperature. A large amount of fine particles precipitated in the grains interior and at the grain boundaries when heated to the compression temperatures and soaked for 5min below 450 °C. However, the volume fraction of particles decreased significantly when soaked for 5 min at 500 °C, and the coarse particles precipitated mainly at the grain boundaries. Hot deformation at the temperature of 500 °C around and at the strain rate range of 0.1s-1 was desirable for NZ30K alloy.

Microstructure and Properties of 1.0C-1.5Cr Bearing Steel in Processes of Hot Rolling, Spheroidization, Quenching, and Tempering

2019 ◽  
Vol 90 (3) ◽  
pp. 1800470 ◽  
Author(s):  
Chang-Sheng Li ◽  
Zhen-Xing Li ◽  
Jin-Yi Ren ◽  
Xing-Yang Tu ◽  
Bin-Zhou Li
Keyword(s):  
Hot Rolling ◽  
Bearing Steel ◽  
Microstructure And Properties ◽  
Quenching And Tempering

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

2015 ◽  
Vol 12 (5) ◽  
pp. 431-436 ◽  
Author(s):  
Xu Qiao ◽  
Shunxing Liang ◽  
Lixia Yin ◽  
Dandan Li
Keyword(s):  
Mechanical Properties ◽  
Microstructural Evolution ◽  
Hot Rolling ◽  
Volume Fraction ◽  
Zirconium Alloys ◽  
Preferred Orientation ◽  
Rolling Reduction ◽  
Practical Applications ◽  
Rolled Specimen ◽  
Hot Rolled

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.

Effect of TSCR Process on Cold Rolling Texture of Fe-3% Silicon Steels

2010 ◽  
Vol 160-162 ◽  
pp. 488-491
Author(s):  
Yong Mei Yu ◽  
Yuan Xiang Zhang ◽  
Chang Sheng Li ◽  
Guo Dong Wang
Keyword(s):  
Chemical Composition ◽  
Cold Rolling ◽  
Hot Rolling ◽  
Volume Fraction ◽  
Rolling Texture ◽  
Fiber Texture ◽  
Rolling Reduction ◽  
Cold Rolling Strip ◽  
Rolling Strip ◽  
Cold Rolling Texture

The effect of hot rolling parameters including different hot rolling reduction, soaking time of ingots and chemical composition on cold rolling texture by TSCR process was studied. The result indicates that α fibers and γ fiber texture were affected by hot rolling reduction, and oriented density αfibers texture increases with hot rolling reduction rate increasing, and the texture components is same in the surface and different in the center. The strength of γ fiber texture, from {111}<110>to {111}<112>, is decreasing trendency for ingot soaked for 10min and 20min. however, changing trendency from {111}<110>to {111}<112> in 1/8 thickness and 1/4 thickness of cold rolling strip for ingot soaked for 30min. The volume fraction of {111}<112> is rising with the ingot soaked time and the maxium is 3.5 percent, and the volume fraction of {111}<112> is higher in every layer of cold rolling strip whose chemical composition includes Sn than without Sn, the volume fraction of {111}<112> is higher in 1/8 and 1/4 layers than the surface and center layers.

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