焊补缩孔热循环对奥-贝球铁HAZ组织与性能的影响

采用模拟焊接热循环方法 ,研究奥氏体区不同热循环对奥 贝球铁缩孔焊补热影响区 (HAZ)显微组织、抗拉强度、冲击韧性和断口形态的影响。试验结果表明 :模拟焊补缩孔HAZ中奥氏体区上限温度区显微组织变化大 ,力学性能差 ,是焊接接头的最薄弱环节 ,而在贝氏体转变温度区间内施加缓冷的热循环 ,奥氏体区内产生一定量奥 贝组织 ,力学性能改善 ,达到与奥 贝球铁母材的力学性能相匹配。

Effect of the Thermal Cycle of Welding Shrinkage Hole on Microstructure and Properties of Heat-Affected Zone Austempered Ductile Iron

The effect of the different thermal cycling simulations on the microstructure,fracture strength ( σ o ),impact toughness ( α k ) and fracture morphology of heat affect zone of austempered ductile iron are investigated by means of the welding thermo simulation test.Experiment results show that the mechanical properties of austenite zone with the top temperature are impaired because of microstructural change and it is the weakest zone in HAZ.And then,by adding the thermal cycle for slow cooling in bainite transformation zone,the austemite and bainite in austenite zone appear and its mechanical properties can be improved and match those of austempered ductile iron.