30CrMnSi, one kind of the medium-carbon quenching and tempering steel（ MCQTT） , has been widely utilized in some industrial fields. However, just like some other MCQTT, this kind of steel also faces such problem as ...30CrMnSi, one kind of the medium-carbon quenching and tempering steel（ MCQTT） , has been widely utilized in some industrial fields. However, just like some other MCQTT, this kind of steel also faces such problem as delayed cracking in its welded joints. In this paper, the delayed cracking and microstructure of the joints of 30CrMnSi steel were researched by SEM. Moreover, a method called welding with trailing impacting and rolling （WTIR） was utilized to solve the delayed cracking problem by decreasing the residual welding stress in the joint of 30CrMnSi. The crack-free joints of 30CrMnSi steel were obtained by using optimized parameters.展开更多
From the viewpoint of welding mechanics, two new welding methods-welding with trailing peening and welding with trailing impactive rolling were introduced. For aluminum alloy thin-shell structures with high strength, ...From the viewpoint of welding mechanics, two new welding methods-welding with trailing peening and welding with trailing impactive rolling were introduced. For aluminum alloy thin-shell structures with high strength, welding will lead to hot cracking, poor joint and distortion. In order to solve them, trailing impactive device was used behind welding torch to impact the different positions of welded joints, thus realizing the welding with free-hot cracking, low distortion and joint strengthening. By use of impactive rolling wheels instead of peening heads, the outlook of welded specimen can be improved and stress concentration at weld toes can be reduced. Equipment of this technology is simple and portable. It can used to weld sheets, longitudinal and ring-like beams of tube-like structures, as well as the thin-shell structures with closed welds such as flanges and hatches. So the technology has the wide application foreground in the fields of aviation and aerospace.展开更多
文摘30CrMnSi, one kind of the medium-carbon quenching and tempering steel（ MCQTT） , has been widely utilized in some industrial fields. However, just like some other MCQTT, this kind of steel also faces such problem as delayed cracking in its welded joints. In this paper, the delayed cracking and microstructure of the joints of 30CrMnSi steel were researched by SEM. Moreover, a method called welding with trailing impacting and rolling （WTIR） was utilized to solve the delayed cracking problem by decreasing the residual welding stress in the joint of 30CrMnSi. The crack-free joints of 30CrMnSi steel were obtained by using optimized parameters.
文摘From the viewpoint of welding mechanics, two new welding methods-welding with trailing peening and welding with trailing impactive rolling were introduced. For aluminum alloy thin-shell structures with high strength, welding will lead to hot cracking, poor joint and distortion. In order to solve them, trailing impactive device was used behind welding torch to impact the different positions of welded joints, thus realizing the welding with free-hot cracking, low distortion and joint strengthening. By use of impactive rolling wheels instead of peening heads, the outlook of welded specimen can be improved and stress concentration at weld toes can be reduced. Equipment of this technology is simple and portable. It can used to weld sheets, longitudinal and ring-like beams of tube-like structures, as well as the thin-shell structures with closed welds such as flanges and hatches. So the technology has the wide application foreground in the fields of aviation and aerospace.
