环境介质对ASTM A572 Gr65钢疲劳行为的影响  

Effect of Environmental Factors on Fatigue Behavior of ASTM A572 Gr65 Steel

作　　者：胡张翊 张红霞[1] 闫志峰[1] 雷鹏飞 赵庆鲁 魏湛橙 HU Zhang-yi;ZHANG Hong-xia;YAN Zhi-feng;LEI Peng-fei;ZHAO Qing-lu;WEI Zhan-cheng(School of Materials Science and Engineering,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学材料科学与工程学院,太原030024

出　　处：《表面技术》2023年第12期399-407,共9页Surface Technology

基　　金：山西省自然科学基金(RD2000001936)。

摘　　要：目的探究不同环境对ASTM A572 Gr65低合金结构钢疲劳强度的影响。方法在实验室、去离子水和NaCl(3.5%)水溶液环境下进行材料的旋转弯曲疲劳试验,利用疲劳试验设备和显微硬度仪探讨不同环境介质下ASTM A572 Gr65低合金结构钢的疲劳强度和断口附近硬度的变化情况,并通过扫描电子显微镜(SEM)和能谱仪(EDS)等对断口腐蚀形貌及腐蚀产物进行分析。结果ASTM A572 Gr65钢在实验室环境下的疲劳强度为380 MPa,在添加去离子水和NaCl水溶液时的疲劳强度分别为280、80 MPa,分别下降了约26.3%、78.9%;其微观组织为珠光体和铁素体,在疲劳破坏后靠近断口处试样的晶粒存在明显的细化现象,而远离断口的母材微观组织均匀,断口附近的显微硬度因位错运动约升高了10.4HV0.5,当距离增加,硬度逐渐趋于母材本身的硬度时,改变距离约为6 mm;与实验室环境相比,在去离子水和NaCl水溶液中均存在多个裂纹源,这对于疲劳断裂破坏起到了加速作用,疲劳断口表面分区不明显,断口表面存在氧化腐蚀产物和二次裂纹。结论在添加去离子水和NaCl水溶液后,会加速ASTM A572 Gr65钢疲劳强度的降低,疲劳的加速由载荷疲劳、电化学氧化腐蚀及氢脆共同作用所致。In the actual service environment,the low alloy and high strength structural steel will be affected by the cyclic alternating load and corrosion damage caused by the corrosive medium,so that the service time of structural steel will be significantly shortened.The work aims to study the fatigue strength and fracture mechanism of ASTM A572 Gr65 low alloy high strength structural steel under different environments.According to the standard,ASTM A572 Gr65 structural steel was made into standard samples with a length of 52 mm.Rotary bending fatigue tests were carried out on QBWP-6000 rotary bending fatigue test machine under the environment of laboratory,deionized water and 3.5%NaCl solution,and the loading frequency was 100 Hz.The fixed stress ratio of the rotary bending fatigue testing machine was R=−1.When the sample failure or loading times reached 107 times,the test was stopped and the fatigue test value was recorded.In origin software,the experimental values under different strength were fitted to obtain the fatigue strength under this environment,and the fatigue strength of structural steel under different environments was compared.The sample was cut with wire cutting and the cross section was polished,and corroded with 4%nitrate alcohol solution.The microstructure of the fracture was observed by metallography microscope(CX40M)and scanning electron microscope(ZEISS Gemini 300).The energy spectrum of each corrosion fatigue fracture was collected by energy spectrometer,and the components were analyzed.Then,the changes of microhardness values near the fracture were measured by microhardness tester(ZHVST-1000C)to explore the fatigue failure mechanism under different environments.The fatigue strength of ASTM A572 Gr65 steel in the laboratory environment was 380 MPa,but the fatigue strength under deionized water and NaCl solution was 280 MPa and 80 MPa,which decreased by 26.3%and 78.9%,respectively.After fatigue failure,the grain of the sample near the fracture was obviously refined and some of the grains were elon

关 键 词：ASTM A572 Gr65低合金结构钢 旋转弯曲疲劳 氧化腐蚀 去离子水 NACL水溶液 疲劳强度 

分 类 号：TG172[金属学及工艺—金属表面处理]