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在应变速率为5×10-5~2×10-4 s-1范围内以及不同温度(25~700 ℃)下对标准热处理态11Cr3W3Co钢进行拉伸试验,分析了不同温度下出现的锯齿流变行为.结果表明:在285~325 ℃区间出现了正常PLC效应,锯齿形成激活能约为124 kJ·mol-1,锯齿流变主要由固溶的置换原子铬与运动位错之间相互作用引起;在325~365 ℃区间出现了异常PLC效应,这一方面是因为随着拉伸温度升高,溶质原子的扩散能力增强,以至于原子气团不能稳定存在,导致动态应变时效作用减弱,另一方面是因为随温度升高,析出相开始成为溶质原子的湮没源,使得锯齿消失;在高温下,强度的急剧降低和塑性的急剧升高说明动态回复在塑性变形过程中起到主要的作用.

Tensile test was carried out on 11Cr3W3Co steel in standard heat treatment state at different strain rates (5×10-5-2×10-4 s-1) and different temperatures(25-700 ℃), and the serrated flow behavior at different temperature of the steel was analyzed.The results indicate that the normal Portevin Le Chatelier (PLC) effect with sawtooth formation activation energy of 124 kJ·mol-1 occurred at intermediate temperature of 285-325 ℃, serrated flow behavior was mainly caused by the interaction between substitutional solute chromium atoms and moving dislocations;regarding the abnormal PLC effect appeared at temperatures of 325-365 ℃, one possible reason is that the diffusion ability of solute atoms was strong with the increase of tensile temperature so that solute atmosphere was unstable to be present, resulting in a weaken of dynamic strain aging (DSA), another possible reason is that precipitates become sink positions due to the increase of temperature, resulting in a disappearance of serrated flow;at high temperature, rapid reduce in strength and rapid increase in plasticity imply that dynamic recovery plays a major role during the plastic deformation.