B级钢/Q450NQR1钢搭接接头疲劳性能研究
Study on Fatigue Properties of Lap Welded Joints of B-grade Steel and Q450NQR1
董美云1， 胡 飞2， 谭文一2， 周 海2
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作者单位：1. 大连交通大学 机械工程学院，辽宁 大连 116028；2.大连交通大学 材料科学与工程学院，辽宁 大连 116028
中文关键字：B级钢/Q450NQR1钢；焊趾处打磨；喷丸；搭接接头；P-S-N曲线
英文关键字：B-grade steel / Q450NQR1; dressing the toe zone; blasting shot; lap joints; P-S-N curve
中文摘要：针对以Q450NQR1钢（中梁）为基板、B级钢（上心盘）为腹板模拟实际工装位置，疲劳断裂与货车运营实际工况不符的问题，提出以B级钢为基板、Q450NQR1钢为腹板进行三点弯曲疲劳试验，诱使疲劳裂纹向B级钢侧扩展，研究了MAG气体保护焊B级钢/Q450NQR1钢搭接接头的疲劳性能。结果表明：B级钢/Q450NQR1钢搭接接头的疲劳裂纹多出现在B级钢侧，与货车运营的实际工况相符。在循环次数2 × 106、存活率95%、置信水平90%时，搭接接头焊态、打磨态、喷丸态的疲劳强度分别为201.89、225.36、232.69 MPa；表面机械打磨、喷丸工艺能够较好改善B级钢/Q450NQR1钢搭接接头的疲劳性能。
英文摘要：The result of the fatigue fracture was different from the actual work condition in the simulation of the factual tooling position under the condition that Q450NQR1 steel was used as base plate, B-grade steel（top center plate） was used as web plate. To solve the problem, a three-point bending test was put forward. The fatigue cracks spreaded laterally and the fatigue properties of the lap welded joints of B-grade steel/Q450NQR1 were investigated. The test result shows that the fatigue cracks of the improved sample mostly occurrs on the side of B-grade steel that is corresponding to the situation of the actual work condition of the freight train. The fatigue strength of original butt joints, blasting shot joint, sanding joint are 201.89 MPa, 225.36 MPa，232.69 MPa, respectively under the condition that cycle index is 2×106, fraction surviving is 95%, confidence is 90%. The fatigue properties of the lap welded joints of the B-grade steel/Q450NQR1 greatly improve through treating surface with mechanically polishing and blasting shot.