Cyclic Deformation Behavior and Fatigue Crack Propagation of Low Carbon Steel Prestrained in Tension

J. G. Wang,W. P. Jia,D. Y. Ju

doi:10.1155/2009/657284

Abstract

The tests were performed on low carbon steel plate. In the tension fatigue tests, two angle values (ϕ=0°andϕ=45°,ϕis the angle between the loading and the rolling direction) have been chosen. The influence of strain path change on the subsequent initial work softening rate and the saturation stress has been investigated. Dislocation microstructure was observed by transmission electron microscopy. It was found that the strain amount of preloading in tension has obviously affected the cyclic softening phenomenon and the initial cyclic softening rate. It was observed that the reloading axial stress forϕ=45°case increased more than that ofϕ=0°case, due to the anisotropism of Q235. In the fatigue crack propagation tests, the experimental results show that with increasing the pretension deformation degree, the fatigue crack growth rate increases, especially at the near threshold section.

Highlights

Fatigue as mainly damage form in the process of using is firstly studied [1,2,3]
Nearly 90% of total fatigue of most materials is at the stage of cyclic deformation and crack initiation, so trying to clarify cyclic deformation behavior of materials is of much importance in theory research, and in engineering application
Most research works in literature about this are on the cyclic deformation behavior of annealed materials [4,5,6]

Summary

Introduction

Fatigue as mainly damage form in the process of using is firstly studied [1,2,3]. Nearly 90% of total fatigue of most materials is at the stage of cyclic deformation and crack initiation, so trying to clarify cyclic deformation behavior of materials is of much importance in theory research, and in engineering application. Most research works in literature about this are on the cyclic deformation behavior of annealed materials [4,5,6]. The cyclic deformation behavior of materials with prestrained history has been studied because of its industrial application background [7,8,9]. The present work is mainly about the cyclic deformation behavior and fatigue crack propagation of low carbon steel prestrained

Experimental Procedure

Results and Discussion

Fatigue Crack Growth da dN

Conclusions