红外测温法研究Al-Mg合金中的Portevin-Le Chatelier效应

试件塑性变形过程伴随着机械能向热能的转化.利用红外测温法，通过分析红外热像仪采集的温度场图像，系统研究了Al-Mg合金中的Portevin-Le Chatelier （PLC）效应.在不同应变率下，实验得到了三类锯齿形应力-应变曲线，分析了相应情况下试件温度变化曲线的异同及其原因，探讨了三种类型PLC变形带的空间传播特性.研究发现，试件表面的温升随着应变率的增加而增加；PLC带的倾角转向发生在试件的两端或者带外的温度最高处. 关键词： Portevin-Le Chatelier效应 红外测温 Al-Mg合金

The Portevin-Le Chatelier effect in Al-Mg alloy investigated by infrared pyrometry

Plastic deformation is accompanied by the conversion of mechanical energy into heat. The deformation heterogeneity related to the Portevin-Le Chatelier effect （PLC） in Al-Mg alloy during a tensile test at ambient temperature is investigated through temperature field measurement by infrared pyrometry. Under different applied strain rates, three types of stress-strain curves （types A—C） are obtained respectively. Correspondingly, the similarities and differences of temperature-strain curves are compared and interpreted qualitatively. And the spatial propagating characteristics of the three types of PLC deformation bands are observed and analyzed. The temperature rise on the surface of the specimen increases with the increase of strain rate. And the obliquity of PLC band changes either at the ends of the specimen or at the highest temperature area outside the band.