• CN:11-2187/TH
  • ISSN:0577-6686

›› 1965, Vol. 13 ›› Issue (3): 1-15.

• 论文 •    下一篇

钢在多次冲击载荷下裂纹发展过程的研究

周惠久;黄明志;朱金华   

  1. 西安交通大学
  • 发布日期:1965-06-01

A STUDY OF CRACK PROPAGATION IN STEEL DURING THE COURSE OF FRACTURE DUE TO REPEATED IMPACT

Chow Huei-chiu;Hwang Ming-chih;Chu Chin-hua   

  1. Xian Jiao-Tong University
  • Published:1965-06-01

摘要: 应用在破断面上显微镜直接观察的方法研究了回火碳结构钢在多次冲击载荷下的裂纹发生与发展过程。发现裂纹深度t与冲击次数N之间存在t=t0e(N/b)的指数关系,裂纹发展速度v与裂纹深度t之间存在v=1/b*t的线性关系(相应于普通疲劳德v=Ktn关系式中n=1时的情况)。并得出多次冲击抗力(冲击破断寿命)既决定于裂纹发展速度v又决定于极限裂纹深度tK,它们对冲击破断寿命的影响随钢回火温度或钢中碳含量的变化而互为矛盾的变化着。表明裂纹发展速度主要与强度因素有关,而极限裂纹深度主要与塑性因素有关,二者的最好配合使钢在某一回火温度或某一碳含量出现多冲抗力极值。这就使以前发表的文[3][4][5]中所得多冲抗力基本规律得到了有力的支持,同时为充分发挥结构钢的强度潜力提供了新的依据。

Abstract: Crack initiation and propagation in tempered carbon steels during the course of fracture due to repeated impact have been investigated by direct microscopic observation of fractured surfaces. Results of investigation have shown that, for the materials tested and impact energy level used, the depth of crack (t) is related to the number of blows (N) by an exponential function in the form t=t0e(N/b) while the rate of crack propagation (V) has a straight line relation with its depth (t) given t=t0e(N/b)It has also been shown that the total endurance life is governd both by the rate of crack propagation (V) and the final depth of ,crack (tx). Their effects on the total endurance life vary with the tempering temperature or with the carbon content in steel in the opposite ways indicating that the rate of crack propagat is primarily related to the strength factor while the final depth of crack is primarily related to the ductility or toughness factor. An optimum combination of these two factors results in the appearance of a peak value of total endurance life (resistance against repeated impact)at a certain tempering temperature or a given carbon coatent raoe results strongly supports our view points and general relationships concerning the resistance against repeated impact of tempered carbon steels postulated in papers [3][4][5],while in turn have laid new grounds for the development of strength potentiality of steels.