航空学报 > 1992, Vol. 13 Issue (8): 456-460

300M钢在门坎值附近疲劳裂纹扩展行为的研究

丁传富   

  1. 北京航空材料研究所25室 北京 100095
  • 收稿日期:1991-02-04 修回日期:1991-05-09 出版日期:1992-08-25 发布日期:1992-08-25

INVESTIGATION OF NEAR-THRESHOLD FATIGUE CRACK PROPAGATION BEHAVIOUR IN 300M ULTRA-HIGH STRENGTH STEEL

Ding Chuan-fu   

  1. Beijing Institute of Aeronautical Materials, Beijing, 100095
  • Received:1991-02-04 Revised:1991-05-09 Online:1992-08-25 Published:1992-08-25

摘要:

在实验室空气环境中研究了300M钢等温和油淬状态,五种载荷比下裂纹扩展速率为10~(-7)~10(-3)mm/Cycle的疲劳裂纹扩展行为。着重分析了载荷比和显微结构对门坎值附近裂纹扩展行为的影响。基于在门坎值附近断口表面上所观察到的氧化喾物和沿晶断裂机制,用裂纹闭合和环境效应合理地解释了300M钢在门坎值附近的裂纹扩展特性。

关键词: 门坎值, 裂纹扩展速率, 应力比, 显微结构

Abstract:

In this paper fatigue crack propagation behaviour of 300M ultra-high strength steel has been investigated in laboratorial air over a very wide range of growth rates from 10-7 to 10-3 mm/cycle at the various load ratios R( = 0.05, 0.1, 0.3, 0.5, 0.7) and the two states of heat treatment (quench and isothermal). Particula emphasis has been devoted to the influence of load ratio and microstructure on behaviour of near-threshold fatigue crack growth. According to oxide deposits and intergranular fracture observed on near-threshold fatigue fractures behaviour of near-threshold crack growth in 300M has been explained rationally in terms of the crack closure and environmental effect.

Key words: threshold value, fatigue crack growth rate, load ratio, microstructure