由改善显微组织形态提高钢件疲劳寿命

INCREASING THE FATIGUE LIFE OF STEEL PART BY IMPROVING THE MICROSTRUCTURE MORPHOLOGY

本文探讨研究由改善显微组织形态提高调质高强度钢件疲劳寿命的可能性及相应的机理和途径。实验研究发现,通过改善显微组织到预想的状态,使调质高强度钢应力场强度因子范围门槛值稍有增高,疲劳裂纹扩展速率减低,疲劳寿命明显提高。分析认为,对疲劳寿命的提高是依据作者对改善调质高强度钢强韧化机理和途径的论点而合理设计热处理工艺,使这种钢晶粒显著细化,碳化物颗粒极为细小而均匀以及基体韧化的结果。这种组织形态具有阻碍疲劳裂纹扩展、减小应力集中和阻碍新裂纹的产生等作用,是提高疲劳寿命的重要原因。对改善调质态钢的强韧性和提高疲劳抗力的机理和途径作了分析探讨。

In this paper,the effectiveness of increasing the fatigue life of steel part and its mechanism by improving microstructure morphology have been invesfigated. It is experimentally found that the fatigue crack propagation rate of high strength steel decreases and its fatigue life increases owing to the improvement of microstructure morphology,such as the refining of austenite grain and particle size of carbides and the toughening of matrix phase.The morphology serves the function of preventing the propagation fo crack and production of new crack caused by stress concentration,thus increasing the fatigue.The improvement of microstructure morphology results from the rational strengthen-toughening mechanism and heat treat process design suggested by the author.