焊接热循环对Cr-Al低合金钢韧性及组织的影响

Influence of weld thermal cycle on toughness and microstructure of Cr-Al low alloy steel

本研究采用模拟焊接热循环试验方法,测定了Cr-Al钢被加热到不同峰值温度后热影响区冲击韧性的变化。试验结果表明,随着单次热循环峰值温度的提高,热影响区冲击韧性下降,断口形貌从韧窝状变成解理状或准解理状,原奥氏体晶粒尺寸长大,马氏体板条变宽。试验还发现,多次热循环可得到良好的接头性能。随着峰值温度的提高,热影响区冲击韧性增加,断口形貌由脆性特征变为韧性特征。

In this paper, by weld thermo-simulation test with different peak temperatures, the variation of HAZ charpy impact toughness of Cr-Al steel was determined. The results obtained from the test showed that when the peak temperature of single thermal cycle increased,the HAZ impact toughness decreased, the fractographic appearances changed from dimple pattern to cleavage or quasicleavage one, the grain size of prior austenite grew, and the martensitic laths became wide. It was also found that the excellent properties of welding joint could be obtained by applying multiple thermal cycle. By increasing the peak temperatures the HAZ impact toughness could be increased, and the fractographic appearances could be changed from brittle characteristic to ductile one.