预应变对中碳TRIP钢氢吸附及延迟断裂行为的影响

Effect of prestraining on hydrogen absorption and delayed fracture behavior of a medium-carbon TRIP steel

采用电化学充氢、热脱氢分析仪(TDS)及慢应变速率试验(SSRT)研究了预应变对一种Si-Mn系中碳TRIP钢的氢吸附及延迟断裂行为的影响。结果表明,具有多相组织的等温淬火(AT)试样在拉伸变形过程中,残留奥氏体在应变诱导下转变为马氏体,其转变量随着预应变量的增大而增加。具有回火马氏体组织的淬火回火(QT)试样和AT试样在充氢后的氢逸出曲线上均具有一个逸出峰,其峰值温度分别约为90℃和130℃,该峰值温度随预应变量的增大而升高。随着预应变量的增加,充氢QT样和AT样的氢含量逐渐增加,这导致氢致塑性损失增加,其中AT样的氢致塑性损失要明显高于QT样。这表明,预变形AT样的延迟断裂敏感性较高。

Hydrogen absorption and delayed fracture behavior of a medium-carbon Si-Mn type TRIP steel was studied by electrochemical charging, thermal desorption spectrometry（TDS） analysis and slow strain rate testing （SSRT）. The results show that there is a nearly linear relationship between the amount of strain-induced transformation and tensile prestraining for the austempered （AT） specimen having multiphase microstrueture. There is only one hydrogen desorption peak for both quenched and tempered （QT） specimen and AT specimen, with their peak temperatures around 90 ℃ and around 130℃ , respectively. The peak temperature tends to increase with increasing prestraining. The amount of charged hydrogen content increases with increasing prestraining and therefore hydrogen-induced ductility loss increases for both AT and QT specimens. However, ductility loss of AT specimen is more significant than that of QT specimen, that is to say, prestrained AT specimen has higher delayed fracture sensitivity than that of QT specimen.