焊接及热处理对T250马氏体时效钢薄壁旋压圆筒性能的影响

Infulence of Welding and Heat Treatment on T250 Maraging Steel Thin-Walled Spinning Cylinder

采用脉冲TIG焊对T250马氏体时效钢薄壁旋压圆筒进行焊接,通过优化焊接工艺参数,得到了外观成形良好,内部缺陷达到QJ175—93 0级标准要求的焊缝。在焊前和焊后对T250马氏体时效钢薄壁旋压圆筒进行了热处理,研究了热处理对焊接接头金相组织、显微硬度、角变形和力学性能的影响。结果表明:时效处理后,焊缝金属枝晶晶界中存在逆转变奥氏体组织,显微硬度低于母材;熔合线附近焊接热影响区晶粒长大,最大处晶粒约为基材的6倍;焊前时效处理大幅度减小了焊接接头角变形;在焊后对试样进行500℃时效处理的情况下,焊前时效处理使焊接接头抗拉强度和弯曲角都有所提高;焊前对旋压圆筒进行500℃时效处理,焊后进行500℃时效处理,得到了最佳焊缝强韧性匹配。

This paper adopts pulse TIG welding to weld the T250 maraging steel thin-walled spinning cylinder.By optimizing process parameters,weld joints with weld formation and internal defects meet the requirement of QJ175 -93 0 grade was obtained.Heat treatment was carried out to T250 maraging steel thin-walled spinning cylinder prior to weld and post weld.The influence of heat treatment on microstructure,microhardness,angular distortion and mechanical properties of weld joints was studied.The results showed that after aging treatment,reverted austenite exist in dendritic grain boundary in weld metal,microhardness is lower than basic metal.The grain near the fusion lion of welding heat affected zone grow and the largist grain size was 6 times of base metal.Heat treatment prior to weld decreased the angular distortion greatly.On the premise of 500℃ aging treatment post weld,aging treatment prior to weld improve the tensile strength and the bending angle.The best strength and toughness properties was obtained by 500℃ aging treatment prior to weld and 500℃ aging treatment post weld.