Abstract

Torsional fatigue behaviour of steel is influenced by various significant factors on the surface of steel such as the stress state, the metallurgical conditions and the surface roughness etc. This research presents the results of the studies conducted on the torsional fatigue life of steel for different surface stresses, conditions and microstructures. Based on the results, inferences were derived out of the factors and conditions which are instrumental in increasing the fatigue performance. This research is done with the purpose of increasing the fatigue performance of power train shafts processed through vacuum carburizing followed by second tempering. The fatigue tests were conducted using a bi-directional torsional cyclic loading in a MTS make torque testing machine. Various researches has been conducted in this paper to find out the impact of surface roughness, second tempering, inter granular oxidation and carbon case depth on the transmission shafts. The existence of surface retained austenite has not yielded a notable enhancement in fatigue performance in the power train shaft whereas existence of martensite with minimum fraction of retained austenite enhanced the fatigue performance significantly from 12,000 to 35,000 cycles on ± 3100 N m torque load.

Graphic Abstract

摘要

钢的扭转疲劳行为受钢表面应力状态，冶金条件和表面粗糙度等各种重要因素的影响。本研究提出了针对不同表面的钢扭转疲劳寿命的研究结果。应力，条件和微观结构。根据结果​​，从有助于提高疲劳性能的因素和条件中得出推论。进行这项研究的目的是提高通过真空渗碳然后二次回火处理的动力传动系统轴的疲劳性能。疲劳测试是在MTS make扭矩测试机中使用双向扭转循环载荷进行的。本文进行了各种研究，以了解表面粗糙度，二次回火，颗粒间氧化和碳箱深度对传动轴的影响。表面残留奥氏体的存在并未显着提高动力传动系统轴的疲劳性能，而存在具有最小残留奥氏体分数的马氏体，则在±3100 N m的扭矩负载下将疲劳性能显着提高了12,000至35,000个循环。

图形摘要