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利用激光冲击波对X80管线钢焊接接头进行了表面强化处理,通过拉伸疲劳对比试验,采用罗卡提法求出激光冲击强化处理前后X80管线钢焊接接头的疲劳极限。用扫描电镜和X射线衍射仪分析了激光冲击处理前后X80管线钢焊接接头断口形貌和残余应力,并对激光冲击处理提高抗疲劳断裂机理进行探讨。结果表明,激光冲击处理引入了-339 MPa的残余压应力,使X80管线钢焊接接头疲劳强度由445 MPa提高到496 MPa,提高了11.2%;原始状态的试样疲劳裂纹起始于试样表面,经激光冲击处理后焊接接头疲劳源转移至次表层,表层晶粒细化和残余压应力是主要机制,提高了X80管线钢焊接接头的疲劳性能。
X80 pipeline steel welded joints were strengthened by laser shock wave. The fatigue limit of X80 pipeline steel welded joints before and after laser shock treatment was obtained by Tensile fatigue comparison test and Rocca method. The fracture appearance and residual stress of X80 pipeline welded joints before and after laser shock were analyzed by scanning electron microscopy and X-ray diffraction. The mechanism of laser shock treatment to improve fatigue fracture resistance was also discussed. The results show that the residual compressive stress of -339 MPa is introduced into the laser shock treatment, which increases the fatigue strength of welded joint of X80 pipeline steel from 445 MPa to 496 MPa, an increase of 11.2%. The fatigue crack of the original specimen starts from the surface of the specimen , The fatigue source of weld joint transferred to subsurface layer after laser shock treatment is the main mechanism of surface grain refinement and residual compressive stress, which improves the fatigue property of welded joint of X80 pipeline steel.