摘要:
重点研究钒微合金化高锰(20%~30%)TWIP钢的静态软化和应变诱导析出行为,考察了不同钒含量(0.1%、0.2%)和碳含量(0.2%、0.6%、1%)的影响,目标是确定钒在热轧后还能有进一步析出强化作用的条件(如:成分、热加工参数)。在700~1100℃温度范围内进行了双道次扭转试验,还对卷取进行了模拟(从700℃到550℃)。采用先进的分析方法,如通过EBSD来确定晶粒尺寸和再结晶分数,采用TEM来分析析出物。结果表明,在热加工温度范围内,钒的析出相对迟缓,而且只在20%Mn-0.6%C-0.2%V或30%Mn-1%C-0.1%V的成分条件下发生。将碳含量降低到0.2%时,只在650℃和700℃模拟卷取后才能观察到析出物。另外,在有应变诱导析出发生的情况下,回复、再结晶和应变诱导析出之间有着复杂的相互影响。静态再结晶被明显推迟,导致回复对软化动力学具有重要影响。
Abstract:
The present work focuses on the study of static softening and strain-induced precipitation in high Mn (20%~30 %) TWIP steels microalloyed with vanadium. The effect of different V (0.1%,0.2%) and C (0.2%,0.6%,1 %) contents has been investigated. The aim is to evaluate at which conditions (composition/hot working parameters) vanadium remains available for further precipitation hardening after hot rolling. Double hit torsion tests at temperatures in the range 700~1100 ℃ and coiling simulations (from 700 to 550 ℃) were carried out. Advanced characterization techniques have been used,such as EBSD for the determination of the grain size and recrystallized fraction,and TEM for the analysis of the precipitation. The results show that precipitation of vanadium at the hot working temperature range is relatively sluggish. It only occurs for the combinations of 20Mn- 0.6C- 0.2V or 30Mn- 1C-0.1V. Reducing the carbon content to 0.2C,precipitates were only observed after coiling simulation at 650 and 700 ℃. Moreover,in those cases where strain-induced precipitation is observed there is a complex interaction between recovery,recrystallization and strain-induced precipitation. Static recrystallization is severely delayed leading to a major contribution of recovery to softening kinetics.
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