高强钢断裂韧性与疲劳裂纹扩展评价方法研究进展

Research Progress on Evaluation Methods of Fracture Toughness and Fatigue Crack Growth in High-strength Steel

高强钢在服役过程中长期经受循环载荷作用,其疲劳与断裂问题一直是热点研究方向。准确评估高强钢的疲劳寿命和监测高强钢构件的服役状态,是保证大型装备安全运行的关键。随着断裂力学发展,损伤容限设计已成为航空、航天、核电和高速铁路等重要工业领域的关键构件疲劳断裂控制方法。作为损伤容限设计中的关键力学参量,准确掌握断裂韧性和疲劳裂纹扩展的评价方法,能够对解决大型构件完整性和可靠性研究的瓶颈问题中起到承上启下的作用。首先概述高强钢的分类和失效问题,分析断裂韧性和疲劳裂纹扩展的表征形式。从尺寸效应和能量准则等方面系统阐述了小试样估算断裂韧性的方法,并探讨高强钢中拉伸性能、冲击韧性与断裂韧性的定量关系研究进展。从近门槛值区、稳态区和全阶段区域分别阐述疲劳裂纹扩展模型和方法,并重点介绍贴近实际工程应用中的应力比和尺寸效应两方面的研究进展。最后提出高强钢断裂韧性和疲劳裂纹扩展评估及测试技术研究中值得关注的若干问题。

The issue of fatigue and fracture in high-strength steel has always been a hot research direction due to long time service under cyclic loading.Accurately evaluating the fatigue life and monitoring the service status of high-strength steel are crucial to ensure the safe operation of large equipment.With the development of fracture mechanics,damage tolerance design has become a significant fatigue fracture control method in industrial fields such as aviation,aerospace,nuclear power and high-speed railway.As the key parameters in damage tolerance design,accurately understanding of evaluation methods for fracture toughness and fatigue crack growth plays a significant connecting role in solving the bottleneck problem of integrity and reliability research on large components.In this study,the classification and failure of high-strength steels are firstly reviewed.Then,the characterization forms of fracture toughness and fatigue crack growth are analyzed.The small-sample methods for estimating fracture toughness are systematically elaborated from the size effect and energy criterion.The research progress on the quantitative relationship between tensile properties,impact toughness and fracture toughness are discussed.The models and methods of fatigue crack growth in the near-threshold region,steady-state region and whole-stage region are illustrated respectively.Additionally,the stress ratio and size effect on the fatigue crack growth of high-strength steel are emphasized.Finally,several open problems in the field of fracture toughness and fatigue crack growth are addressed for future studies.