强烈冷拉塑性变形及退火处理对珠光体钢组织性能的影响

Effects of Heavily Cold-drawn Deformation and Annealing Treatment on Structure and Properties of Pearlitic Steel

经过强烈变形,珠光体钢组织中铁素体和渗碳体均发生强烈细化,形成了超细晶、纳米晶;材料变形处理后经200℃退火,组织中析出大量纳米尺度渗碳体颗粒,抗拉强度升高;经300℃退火,渗碳体发生相平衡回复,各种晶体缺陷发生合并、抵消;经400℃退火,铁素体发生再结晶,渗碳体晶粒长大;经500℃退火,出现等轴晶组织;而更高温退火,渗碳体发生合并形成片状组织,强度大幅下降,韧性开始升高。

Under heavily cold-drawn deformation, the ferrite lamellae and cemmentite lamellae in pearlitic steel change into ultra-fine and nano-sized grains. And then, via annealing at 200℃, numerous nano-sized eemmentite globules are precipitated, and the tensile strength is also improved;via annealing at 300℃, the equilibrium of cemmentite phase is restored, many defects are merged;via after annealing at 400℃, the recrystallization of ferrite occurs, and the eemmentite globules become coarser;when the annealing temperature is up to 500℃, there are all equal-axed grains in the structure;when annealing temperature is higher than 550℃, cemmentite globules are merged into cemmentite lamellae, the ductility of steel wire improves remarkably, while the tensile strength decreases a lot.