TWIP钢激光焊接接头组织性能及断裂行为

Microstructure,mechanical properties and fracture behavior of laser welded joint of a TWIP steel

采用激光焊接方法对Fe-Mn-Al-Si系TWIP钢进行焊接,观察和测定了接头的微观组织和硬度,研究了接头的拉伸、冲击性能及断裂行为。结果表明,在拟定焊接工艺下,TWIP钢接头无明显热影响区,焊缝区晶粒发生细化且平均硬度值最大;接头伸长率低于母材,拉伸断裂发生在母材区域;TWIP钢在-196℃以上温度区间均表现出良好的冲击韧性;接头在-117℃以上温度区间的冲击性能与母材相当,但在-196℃时,接头的冲击吸收功大幅下降,断口上观察到脆性断裂特征。

Microstructure,hardness,tensile property,impact property at test temperatures and fracture behavior of the laser welded TWIP steel were studied and characterized in this work. The results show that the maximum hardness value of the welded joint（ WJ） is located in the fusion zone,in which the grains are refined compared with that of the base metal（ BM）,and no obvious heat affect zone is observed. All welded specimens for tensile test fracture at BM region and the elongation of the WJ is lower than that of the BM obviously.Moreover,the BM shows good toughness at- 196 ℃ in charpy impact test. And the impact properties of the welded joint are similar with that of the BM at the temperature above- 117 ℃. However,at- 196 ℃,the impact absorbed energy of the WJ decreases steeply and the brittle frature characteristic is observed on the fracture surface of the all test specimens.