转向架用SMA490BW钢焊接接头超高周疲劳性能
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摘要
采用超声疲劳试验方法对SMA490BW钢焊接接头的超高周疲劳性能进行研究,通过X射线应力仪对焊接试样残余应力进行测试,采用扫描电镜对疲劳裂纹的萌生、扩展及疲劳断裂机理进行观察和分析.结果表明,SMA490BW钢母材的疲劳性能远高于焊接接头,在1×108循环周次条件下,接头的疲劳强度为141 MPa,仅为母材的44.2%.接头裂纹主要萌生于焊趾表面缺陷处,疲劳断裂机理表现为准解理断裂,并伴有塑性变形痕迹.焊趾处几何不连续造成的应力集中和焊缝及其附近区域一定的残余拉应力,以及接头各微区组织和性能的不均匀性,是导致焊接接头疲劳性能偏低的主要原因.
Very high cycle fatigue properties of SMA490 BW steel welded joints for train bogie were investigated by the ultrasonic fatigue testing method. The residual stress of the welded joint was tested through X-ray stress tester. Fatigue crack initiation, propagation and fatigue fracture mechanism were observed and analyzed using scanning electron microscopy. Experimental results show that fatigue property of SMA490 BW steel base metal is much higher than that of the welded joint. Under the condition of 1 ×108 cycles fatigue life, the fatigue strength of welded joint is141 MPa, while that is only 44.2% of base metal. Fatigue cracks of welded joint initiated mainly at surface defects of welded toe, and the fatigue fracture mechanism is exhibited as quasi-cleavage fracture, which accompanied by the traces of plastic deformation in the fracture surface. Residual tensile stress and stress concentration at welded toe, and nonuniformity of microstructure and properties in welded zone are the main factors causing low fatigue property of the welded joint.
Very high cycle fatigue properties of SMA490 BW steel welded joints for train bogie were investigated by the ultrasonic fatigue testing method. The residual stress of the welded joint was tested through X-ray stress tester. Fatigue crack initiation, propagation and fatigue fracture mechanism were observed and analyzed using scanning electron microscopy. Experimental results show that fatigue property of SMA490 BW steel base metal is much higher than that of the welded joint. Under the condition of 1 ×108 cycles fatigue life, the fatigue strength of welded joint is141 MPa, while that is only 44.2% of base metal. Fatigue cracks of welded joint initiated mainly at surface defects of welded toe, and the fatigue fracture mechanism is exhibited as quasi-cleavage fracture, which accompanied by the traces of plastic deformation in the fracture surface. Residual tensile stress and stress concentration at welded toe, and nonuniformity of microstructure and properties in welded zone are the main factors causing low fatigue property of the welded joint.
引文
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[2]Hong Y S,Zhao A G,Qian G A,et al.Fatigue strength and crack initiation mechanism of very-high-cycle fatigue for low alloysteels[J].Metallurgical and Materials Transactions A,2012,43(8):2753-2762.
[3]何超,崔仕明,刘永杰,等.气孔对铝合金焊接接头超长疲劳寿命的影响[J].焊接学报,2014,35(11):18-22.He Chao,Cui Shiming,Liu Yongjie,et al.Effect of pore on super long fatigue life of aluminium alloy welded joint[J].Transactions of the China Welding Institution,2014,35(11):18-22.
[4]马婧,赵子华,聂宝华,等.TC21钛合金电子束焊接接头超高周疲劳行为研究[J].机械工程学报,2015,51(12):69-75.Ma Jing,Zhao Zihua,Nie Baohua,et al.Research on very high cycle fatigue behavior of the electron beam weldment for TC21 titanium alloy[J].Journal of Mechanical Engineering,2015,51(12):69-75.
[5]Murakami Y,Yokoyama N N,Nagata J.Mechanism of fatigue failure in ultralong life regime[J].Fatigue and Fracture of Engineering Material and Structures,2002,25(8-9):735-746.
[6]Mayer H,Haydn W,Schuller R,et al.Very high cycle fatigue properties of bainitic high carbon-chromium steel[J].International Journal of Fatigue,2009,31(2):242-249.
[7]Chai G.The formation of subsurface non-defect fatigue crack origins[J].International Journal of Fatigue,2006,28(11):1533-1539.
[8]闫桂玲,王弘,康国政,等.高速列车用6065A铝合金超高周疲劳性能试验研究[J].中国铁道科学,2014,35(1):67-71.Yan Guiling,Wang Hong,Kang Guozheng,et al.Experimental study on the very high cycle fatigue properties of 6065 aluminum alloy for high speed train[J].China Railway Science,2014,35(1):67-71.
[9]刘龙隆,轩福贞,朱明亮.25Cr2Ni2MoV钢焊接接头的超高周疲劳特性[J].机械工程学报,2014,50(4):25-31.Liu Longlong,Xuan Fuzhen,Zhu Mingliang.Very high cycle fatigue behavior of 25Cr2Ni2MoV steel welded joint[J].Journal of Mechanical Engineering,2014,50(4):25-31.
[10]邓彩艳,王红,龚宝明,等.加载频率及焊接缺陷对5A06铝合金TIG焊接头超高周疲劳性能的影响[J].焊接学报,2015,36(12):61-64.Deng Caiyan,Wang Hong,Gong Baoming,et al.Effects of loading frequency and welding defects on veryhigh-cycle fatigue properties of 5A06 aluminum alloy TIG welded joints[J].Transactions of the China Welding Institution,2015,36(12):61-64.
[11]王东坡,龚宝明,吴世品,等.焊接接头与结构疲劳延寿技术研究进展综述[J].华东交通大学学报,2016,33(6):1-14.Wang Dongpo,Gong Baoming,Wu Shipin,et al.Research review on fatigue life improvement of welding joint and structure[J].Journal of East China Jiaotong University,2016,33(6):1-14.
[12]魏康,何柏林.基于ABAQUS的转向架十字焊接接头应力集中系数分析[J].兵器材料科学与工程,2016,39(1):41-44.Wei Kang,He Bolin.Analysis of stress concentration coefficient of welded cross joint of bogie based on ABAQUS[J].Ordnance Material Science and Engineering,2016,39(1):41-44.
[13]刘锁.金属材料的疲劳性能与喷丸强化工艺[M].北京:国防工业出版社,1977.