Fatigue Properties of a Graded Steel Component
Fatigue Properties of a Graded Steel Component
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分级钢构件的疲劳性能
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
M. Besel
中科院分区：
文献类型：
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作者：
A. Brückner;F. Zeismann;M. Besel
将处于软退火条件下的Cr-V合金化可热处理钢的棒材局部加热至高于奥氏体化温度的温度，然后进行一体化成形和冷却过程。所得到的部件具有由马氏体、变形的基体材料和具有混合显微组织的过渡相组成的梯度显微组织。从该组件上切下微型试样，以评估梯度钢在拉伸载荷和循环载荷下的局部性能。马氏体区具有高强度，并显示出相对较长的寿命。主要的损伤累积过程被确定为裂纹萌生从局部缺陷。另一方面，基材含有许多裂纹萌生部位。对表面损伤累积过程的原位观察显示了宏观裂纹是如何通过微裂纹的扩展和合并而形成的。它展示了如何将这些发现纳入一个基于机制的寿命模型。
Rods of a Cr-V alloyed heat treatable steel in a soft annealed condition were locally heated to a temperature above austenization temperature and then subjected to an integrated forming and cooling procedure. The resulting component possesses a graded microstructure consisting of martensite, deformed base material and a transition phase with mixed microstructure. Miniature specimens were cut from this component which allowed assessing the local properties of the graded steel both under tensile loading and under cyclic loading. The martensite region had high strength and showed comparatively long lifetimes. The dominant damage accumulation process was identified to be crack initiation from local defects. The base material, on the other hand, contained numerous crack initiation sites. In-situ observation of the damage accumulation process on the surface showed how macroscopic cracks were formed by microcrack growth and coalescence. It is shown how these findings can be incorporated into a mechanism-based lifetime model.Copyright © 2009 by ASME