海洋工程结构用钢服役环境模拟及DH36钢腐蚀疲劳裂纹扩展性能研究  

Corrosion Fatigue Crack Propagation Performance of DH36 Steel in Simulated Service Conditions for Offshore Engineering Structures

作　　者：刘冬[1,2] 刘静 黄峰[1] 杜丽影[2] LIU Dong;LIU Jing;HUANG Feng;DU Liying(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6期959-965,共7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：利用自行研制的海水腐蚀疲劳的试验装备开展了海洋工程结构用钢DH36在人造海水环境中不同应力比、频率、温度、流速下的腐蚀疲劳裂纹扩展速率特性,以及不同频率下腐蚀裂纹扩展过程中电化学行为研究。结果表明:应力比(R)越高,相同裂纹尖端应力场幅值条件下,疲劳裂纹扩展速率越快,疲劳裂纹扩展速率门槛值ΔKth越低。R=0.3和R=0.5时疲劳裂纹扩展速率相对R=0.1时的平均加速比例达115%和217%。温度越高疲劳裂纹扩展速率越快,30℃时,相对于最低温度(5℃)条件下的平均加速比例为20%。海水流速越快腐蚀疲劳裂纹扩展速率也越快,相对于静止海水环境,0.3 L/min时疲劳裂纹扩展速率的平均加速比例为19%,1 L/min时为34%,到最大流速3 L/min为50%。不同频率下,空气介质中疲劳裂纹的扩展速率基本无差别,但海水介质中的扩展速率差别较大,频率越低腐蚀疲劳裂纹扩展速率越快。通过比较不同频率下腐蚀疲劳裂纹扩展(CFCG)速率与疲劳裂纹扩展(FCG)速率的相对加速比例,可以看出在10 Hz下腐蚀抑制裂纹扩展,而1和0.1 Hz腐蚀加速裂纹扩展,平均加速比例依次为47.8%和261.8%。腐蚀对疲劳裂纹扩展的加速作用可通过原位监控腐蚀疲劳裂纹扩展过程中裂纹尖端区域电化学腐蚀行为得以量化。The corrosion fatigue crack growth(CFCG) of DH36 steel in artificial seawater was studied via a home-made test set, which can accurately control the load, stress ratio, frequency, temperature,flow rate, p H value, ion concentration, and other factors of the artificial seawater, meanwhile, electrochemical monitoring of the whole process could be applied. The results show that the higher the stress ratio R, the faster the CFCG rate. The average acceleration ratio of CFCG rate by R=0.3 and R=0.5 is115% and 217% of that by R=0.1 respectively. On the other hand, the CFCG rate becomes faster with the increase of temperature. The average acceleration ratio at 30 ℃ is only 20% of that at 5 ℃. The CFCG rate turns to be faster with the increase of seawater flow rate. The average acceleration ratio by flow rate of 0.3, 1 and 3 L/min, is 19%, 34% and 50% of that in static seawater, respectively. There is no difference in the fatigue crack growth(FCG) rate in air by changing test frequencies, but there is a great difference in the CFCG rate in seawater, namely the lower the frequency, the faster the CFCG rate. By comparing the CFCG rate with the FCG rate by different frequencies, it shows that seawater corrosion can inhibit the crack growth to certain extent at 10 Hz, but accelerates the crack growth at 1 and 0.1 Hz with an average acceleration ratio of 47.8% and 261.8%. The acceleration effect of corrosion on fatigue crack growth can be quantified by in-situ monitoring the electrochemical corrosion behavior at the crack tip during CFCG.

关 键 词：腐蚀疲劳裂纹扩展速率 应力比 频率 温度 流速 

分 类 号：TG172.5[金属学及工艺—金属表面处理]