预热温度对AH36激光焊缝组织及硬度的影响

Effect of preheating on microstructure and hardness of AH36 laser weld

利用光纤激光器对AH36平板进行对接焊接试验,研究预热对焊缝微观组织的影响。结果表明,无预热时,AH36接头微观组织以板条状马氏体为主,包含少量粒状贝氏体。随预热温度升高,冷却速度降低,焊缝中马氏体含量减少,贝氏体含量上升。当预热温度升至250℃时,微观组织以贝氏体为主,并出现羽毛状上贝氏体组织。测试接头显微硬度,结果表明显微硬度随预热温度升高而降低,与焊缝中马氏体含量变化规律保持一致。

Butt welding experiment of AH36 plate by fiber laser was carried out to study the effect of preheating on the microstructure of weld.The result showed that the microstructure of AH36 joint was dominated by lath martensite(M)and a small amount of granular bainite without preheating.With the increase of preheating temperature,the cooling rate decreased,resulting in the decrease of martensite number and the increase of bainite number in the weld.When the preheating temperature was 250℃,the microstructure was dominated by bainite and feather-like upper bainite.Microhardness of the joint was tested,and the result showed that the microhardness of the joint decreased with the increase of preheating temperature,which was consistent with the variation of martensite content in the weld.