LIU Jing, LI Qiaoyan, XU Hai Long, et al.Research on Welding Repair Technology for Key Components of Rail Vehicles[J].Electric Welding Machine, 2024, 54(9): 47-54.
LIU Jing, LI Qiaoyan, XU Hai Long, et al.Research on Welding Repair Technology for Key Components of Rail Vehicles[J].Electric Welding Machine, 2024, 54(9): 47-54. DOI: 10.7512/j.issn.1001-2303.2024.09.06.
Research on Welding Repair Technology for Key Components of Rail Vehicles
To study the effect of repair welding times on the microstructure and properties of the 30CrMo alloy steel hollow shaft
a key component of the power locomotive bogie
and to optimize its repair welding process
three repair welding tests were conducted on the 30CrMo
alloy steel hollow shaft. Static strength tests
metallographic tests
and fatigue tests were performed on the joints after each repair welding. Static strength tests included tension and bending tests. Metallographic tests observed the microstructure of various regions of the joint. Fatigue tests used rotating bending loading to determine the fatigue limit of the joint. The results showed that after multiple repair weldings
the joint had good tensile properties
and the tensile specimens broke at the base metal; the bending performance was good
and no fracture or crack occurred when the bending angle reached 180°; the impact properties at room temperature and low temperature decreased slightly after multiple repair weldings
meeting the standard requirements; the hardness of the weld after three repair weldings was between 330~340 HV
which was significantly higher than the hardness of the base metal and the heat-affected zone. Metallographic analysis showed that the microstructure of the hollow shaft base metal was tempered sorbite
upper bainite
and massive ferrite
the main microstructure of the heat-affected zone was tempered sorbite and a small amount of massive ferrite
the microstructure of the fusion zone was tempered sorbite
and the weld microstructure was tempered sorbite produced after quenching and tempering. The fatigue limit of the joint met the strength requirements
and the median fatigue limit was the highest in the third repair welding
which was 399 MPa at a specified life of 1×10
7
cycles. Post-weld quenching and tempering could effectively improve the effect of multiple repair weldings on joint properties. After multiple repair weldings
the 30CrMo alloy steel hollow shaft joint had good tensile
bending
and fatigue properties
and the fatigue strength of the joint increased gradually with the increase of repair welding times. This research result provides a theoretical basis for the optimization of the repair welding process of key components of the power locomotive bogie.
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