Abstract：The effect of ultrasonic impact treatment （UIT） on very high cycle fatigue properties of P355NL1 steel welded joint was investigated through ultrasonic fatigue test and UIT test. The results show that the[S-N]curve of the fatigue life，in the 105-109 cycles range，the fatigue properties of impact specimens are higher than that of the as-welded specimens. Under the fatigue life of 1.0×108 cycles，the fatigue strength of as-welded specimen is 139 MPa，the fatigue strength of treated specimen is 217 MPa，the fatigue strength of the treated specimen is improved by 156% compared with the as-welded specimen. This shows that UIT can significantly improve the fatigue strength of welded joint. The fracture surface was observed using scanning electron microscope （SEM），it can be found that the crack is initiated in the welded root surface of specimen. The fatigue fracture of P355NL1 steel welded joint is quasi cleavage fracture. The UIT can improve the fatigue strength of welded joint，but it will not change the fatigue failure mechanism. UIT can reduce the stress concentration at the weld root，and bring in the beneficial compressive stress and the surface grain refinement，so as to improve the fatigue strength of the welded joint.
收稿日期: 2017-06-05
出版日期: 2017-11-14
引用本文:
谢学涛，何柏林，金 辉，吴 剑. 超声冲击对P355NL1钢焊接接头超高周疲劳性能影响[J]. 钢铁, 2017, 52(11): 59-63.
XIE Xue-tao，HE Bo-lin，JIN Hui，WU Jian. Effects of ultrasonic impact treatment on very high cycle fatigue properties of P355NL1 steel welded joint. Iron and Steel, 2017, 52(11): 59-63.
2017, Vol. 52 
