焊后热处理对12Cr18Ni9与Q355D异种钢焊接接头硬度和耐蚀性的影响

针对奥氏体不锈钢12Cr18Ni9与低合金钢Q355D的焊接，采用E308L-16和E309L-16两种不同型号的焊条进行了焊接工艺试验，并对焊接接头进行了450℃、 650℃和850℃不同温度的焊后热处理。利用金相显微镜、维氏硬度计和晶间腐蚀试验对焊接接头组织和性能进行了分析。结果显示，焊缝微观组织主要由奥氏体和少量的铁素体组成；焊缝和12Cr18Ni9母材硬度随着热处理温度升高而不断下降，Q355D母材硬度随热处理温度的升高呈现先降后升的趋势；650℃热处理的焊缝晶间腐蚀最为严重，450℃和850℃热处理的焊缝晶间腐蚀相对较轻。研究表明，焊接材料及焊接工艺的选择较为合理，热处理温度对焊缝与母材的硬度和抗腐蚀性能有一定的影响，焊后热处理温度应该避免晶间腐蚀最严重的温度650℃。

Effect of Post-welding Heat Treatment on Hardness and Corrosion Resistance of Dissimilar Steel 12Cr18Ni9 and Q355D

According to the welding process of austenitic stainless steel 12Cr18Ni9 and low alloy steel Q355D, two different types of electrodes E308L-16 and E309L-16 were used to carry out the welding process test, and the welded joints were subjected to post-welding heat treatment at different temperatures of 450 ℃, 650 ℃ and 850 ℃. The microstructure and properties of the welded joints were analyzed by metallographic microscope, Vickers hardness tester and intergranular corrosion test. The results show that the microstructure of weld is mainly composed of austenite and a small amount of ferrite. The hardness of weld and 12Cr18Ni9 base metal decreases with the increase of heat treatment temperature, while the hardness of Q355D base metal decreases first and then increases with the increase of heat treatment temperature. The weld intergranular corrosion of 650 ℃ heat treatment is the most serious, and the weld intergranular corrosion of 450 ℃ and 850 ℃ heat treatment is relatively light. The research shows that the selection of welding material and welding process is reasonable. The heat treatment temperature has a certain influence on the hardness and corrosion resistance of the weld and base metal. The temperature of post-welding heat treatment should avoid 650 ℃, which is the most serious temperature of intergranular corrosion.