采用U型弯曲试样和双梁试样,研究了超声冲击处理(UIT)对304L/ER316L不锈钢焊接件在沸腾氯化镁溶液中应力腐蚀破裂(SCC)行为的影响。结果表明:UIT在焊接件表面形成一层厚度约为1 mm的压应力变形层,UIT对SCC的影响与试样类型有关;高度变形的U型弯曲试样中母材(BM)区和UIT前后焊接件出现SCC裂纹的时间差别不大,即在此应力应变状态下UIT未显著提高焊接件的SCC抗力;在接近和超过屈服强度的应力水平下,两组双梁试样均显示出同样的SCC敏感性排序,即304L/ER316L＞304L-BM＞304L/ER316L-UIT,表明UIT显著提高了这两种应力下焊接件的SCC抗力;试样裂纹扩展方式均为沿晶+穿晶混合型,焊接件中SCC敏感性排序为焊缝区＜母材区＜热影响区。

The effect of ultrasonic impact treatment (UIT) on the stress corrosion cracking (SCC) behavior of 304L/ER316L stainless steel welded part in boiling magnesium chloride solution was investigated by using U-bend specimens and double-beam bend specimens . The results showed that UIT caused a compressive stress deformation layer with thickness of about 1 mm on surface of the welded part, the effect of UIT on SCC was related to specimen type. There was little difference in the appearence time of U-bend specimen SCC cracks between the base metal (BM) area in high deformed and the welded parts before and after UIT, that is, UIT did not significantly improve the SCC resistance of welded part in such stress-strain condition. At stress levels close to and exceeding the yield strength, both groups of double-beam specimens showed the same SCC susceptibility ranking 304L/ER316L＞304L-BM＞304L/ER316L-UIT, which indicating that UIT significantly improved the SCC resistance of welded parts under the two stress. The crack propagation modes of all specimens were mixed intergranular and transgranular SCC fracture type. The order of SCC sensitivity in welded parts was weld zone