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增加载重量和相应提高轴重,对货车转向架承载铸件提出了更高的要求。在铸件的最重要部位,例如在侧架上,动应力的增加可导致运用中铸件出现疲劳裂纹。运用中铸件内部和表面的各种应力集中,如铸造缺陷、锐边、金属表面微小的不均匀等,是铸件产生疲劳破坏的原因。在转向架定期检修中转向架铸钢侧架的疲劳裂纹是用涂色法目测检查的。这种方法只能发现裂纹开口宽度大于0.1毫米以上的疲劳裂纹。而疲劳裂纹并非总是都有肉眼足以发现的裂口。在许多情况下,裂纹不在铸件表面上,而是隐蔽在内部。某些远离表面的这种内部缺陷,即使裂纹深度只有0.5～1
Increasing the loading capacity and correspondingly increasing the axle load put forward higher requirements on the truck bogie bearing castings. At the most important part of the casting, for example on the side frame, an increase in the dynamic stress can lead to fatigue cracks in the casting during use. The use of a variety of stress concentration within the casting and the surface, such as casting defects, sharp edges, small uneven metal surface, etc., is the cause of fatigue caused by casting. Fatigue cracks on the side frames of the bogie during the periodic maintenance of the bogie were visually inspected with a color coating method. This method can only detect fatigue cracks with a crack opening width greater than 0.1 mm. Fatigue cracks are not always cracks that the naked eye can find. In many cases, the crack is not on the casting surface, but hidden inside. Some of these internal defects away from the surface, even if the depth of the crack is only 0.5 ~ 1