超声冲击对SMA490BW钢焊接接头超高周疲劳性能的影响

发布时间：2019-01-04 20:48

【摘要】：采用超声冲击工艺对转向架用SMA490BW钢对接接头焊趾表面进行冲击处理,研究了超声冲击对接头超高周疲劳性能的影响。借助金相显微镜、SEM和TEM研究了冲击层金相组织、冲击前后焊趾处的形貌及表层金属晶粒细化程度。运用有限元软件计算焊接接头的应力分布,采用X射线应力仪对冲击前后焊趾表层的应力进行了测量和分析。结果表明,在5×10~6循环周次下,冲击态接头和焊态接头的疲劳强度分别为206 MPa和153 MPa,经冲击处理后疲劳强度提高了34.6%。在1×10~8循环周次下,冲击态接头的疲劳强度为195 MPa,与焊态接头的141 MPa相比提高了38.3%。在240 MPa的应力水平下,焊接接头经超声冲击处理后的疲劳寿命提高了7倍。经冲击处理的焊趾部位的应力集中系数下降了19.1%,其表面的残余拉应力得到消除,并转变为有益的残余压缩应力,焊趾表层组织得到明显细化,这3个方面均对提高焊接接头疲劳性能起到了积极贡献。
[Abstract]:The surface of welded toe of butt joint of SMA490BW steel for bogie was treated by ultrasonic impact technology. The effect of ultrasonic impact on the fatigue property of joint was studied. By means of metallographic microscope, SEM and TEM, the microstructure of the impact layer, the morphology of the weld toe before and after impact and the grain refinement of the surface metal were studied. The stress distribution of welded joints was calculated by finite element software, and the stress of welding toe surface before and after impact was measured and analyzed by X-ray stress meter. The results show that the fatigue strength of impact joint and welded joint is increased by 34.6 MPa and 153 MPa, respectively under 5 脳 10 ~ (6) cycles. Under 1 脳 10 ~ (8) cycle, the fatigue strength of the impact joint is MPa, and 38.3 MPa higher than that of the welded joint (141 MPa). At the stress level of 240 MPa, the fatigue life of welded joints was increased by 7 times after ultrasonic shock treatment. After impact treatment, the stress concentration factor of the welded toe decreased by 19.1, the residual tensile stress on the surface was eliminated, and the residual compressive stress was transformed into the beneficial residual compressive stress, and the surface structure of the weld toe was refined obviously. These three aspects have played a positive role in improving fatigue properties of welded joints.
【作者单位】：华东交通大学材料科学与工程学院;中国中车南京浦镇车辆有限公司;
【基金】：国家自然科学基金(51365014) 江西省工业支撑重点项目(20161BBE50072)~~
【分类号】：TG407

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