BSTMUF601板材焊接接头在高温持久应力下的组织转变特性试验研究

Experiment Research on Microstructure Transformation Characteristics of Welded Joints of BSTMUF601 Plate under High Temperature Stress Rupture Test

对马弗管用BSTMUF601厚板焊接接头在高温持久应力下服役前后的试样开展了金相实验,研究了焊接接头在高温持久应力下的组织转变特性。实验结果表明,高温持久应力服役后,母材发生明显的晶粒长大现象并与热影响区相熔合,焊缝区仍为连续冷却的铸态组织,晶粒没有明显长大。焊缝区晶粒随持久试验温度增加而轻微长大,随着持久试验应力增加而轻微减小。持久应力促使晶内出现与水平拉伸方向成40°的裂纹,温度的升高使断口孔洞增多,进而影响材料服役性能。焊缝区析出的碳化物起到了钉扎位错效果,阻止了晶粒的长大,使焊接接头高温持久性能得到提升。

Metallographic experiment was carried out on BSTMUF601 thick plate welded joints for muffler tube before and after the service of high temperature endurance stress, and the microstructure transformation characteristics of the welded joints under high temperature endurance stress were studied. The experiment results show that obvious grain growth of base metal occurs and base metal is fused with the heat affected zone, continuous cooling casting microstructure is observed in the weld zone, and no obvious grain growth appears. The grain size in the welded zone increases slightly with the experiment temperature rising and decreases slightly with the stress rising. The cracks at 40° with horizontal tensile direction are caused by endurance stress, and the number of holes increases with the temperature rising, which influences the service performance of the metal. The grain growth is prevented by pinning dislocation of the precipitated carbide at weld zone, which results in the improvement of high temperature endurance of welded joints.