考虑应力比和门槛值的海水腐蚀疲劳裂纹扩展预测模型  

Corrosion Fatigue Crack Growth Prediction Model Based on Stress Ratio and Threshold for Marine Engineering Steel DH36Z35 in Seawater

作　　者：刘冬[1,2] 刘静 黄峰[1] 杜丽影[2] 彭文杰 LIU Dong;LIU Jing;HUANG Feng;DU Liying;PENG Wenjie(The State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,Wuhan 430081,China;R&D Center of Wuhan Iron&Steel Co.Ltd.,Baosteel Central Research Institute,Wuhan 430080,China)

机构地区：[1]武汉科技大学省部共建耐火材料与冶金国家重点实验室,武汉430081 [2]宝钢股份中央研究院武钢有限技术中心,武汉430080

出　　处：《中国腐蚀与防护学报》2022年第1期163-168,共6页Journal of Chinese Society For Corrosion and Protection

基　　金：国家自然科学基金(51871172);中央指导地方科技发展专项(ZYDD2018026)。

摘　　要：采用自行改造的海水腐蚀疲劳试验机,研究了3 Hz频率、不同应力比R(0.1、0.3、0.5)下,海洋工程用结构钢DH36Z35在空气和人造海水中疲劳裂纹扩展动力学行为。结果表明:相同裂纹尖端应力场强度因子幅值ΔK下,空气和海水环境中都显示疲劳裂纹扩展速率随着应力比R的增加而增加的规律,在近门槛值区间1×10^(-7) mm/cycle≤da/dN≤1×10^(-6) mm/cycle该现象尤其明显;在疲劳裂纹扩展速率da/dN>1×10^(-6) mm/cycle的中速区间,空气中和海水中疲劳裂纹扩展速率出现拐点,高于该拐点海水加速裂纹扩展,低于该拐点海水抑制裂纹扩展,且应力比R越大,拐点对应裂纹扩展速率越高。依据空气和海水中不同应力比和门槛值条件下疲劳裂纹扩展速率实验结果,提出了一种修正的Walker模型,可通过空气中疲劳裂纹扩展速率预测不同应力比下海水环境中疲劳裂纹扩展速率。The fatigue crack growth rate of marine engineering structural steel DH36 Z35 in air and artificial seawater are comparatively assessed by means of a home-made seawater corrosion fatigue machine by applied stress ratio of 0.1, 0.3 and 0.5 with a frequency of 3 Hz. The results show that the fatigue crack growth rate increases with the increase of stress ratio R under the same ΔK both in air and artificial seawater, and this phenomenon is especially evident in the near threshold range 1×10^(-7) mm/cycle≤da/d N≤1×10^(-6) mm/cycle. When the fatigue crack growth rate(da/d N) is above 1×10^(-6) mm/cycle, a flection point may emerge on the curve of fatigue crack growth rate measured both in air and seawater. For the case of testing in the seawater, above the flection point the crack growth is accelerated, whereas below which the crack growth is inhibited. The higher the stress ratio is, the higher the fatigue crack rate corresponding to the inflection point is. Based on the difference of test results in air and artificial seawater by different stress ratio and threshold, a modified Walker model for the prediction of corrosion fatigue crack growth rate is established. By the new prediction model, the fatigue crack growth rate by the applied different stress ratio in seawater can be predicted through the fatigue crack growth rate in air.

关 键 词：海洋工程用结构钢 腐蚀 疲劳裂纹扩展速率 应力比 人造海水 

分 类 号：TG172[金属学及工艺—金属表面处理]