长时服役对20g钢的蠕变疲劳性能影响研究  

Study on the effect of long⁃term service on creep fatigue properties of 20g steel

作　　者：柴星仔 梁斌 陈岗 张天宇 王小威[1,2] 姜勇[1,2] CHAI Xingzai;LIANG Bin;CHEN Gang;ZHANG Tianyu;WANG Xiaowei;JIANG Yong(College of Mechanical and Power Engineering,Nanjing Tech University,Nanjing 211800,China;Institute of Reliability Centered Manufacturing(IRCM),Nanjing Tech University,Nanjing 211800,China;Nanjing Boiler and Pressure Vessel Inspection Institute,Nanjing 210019,China;SINOPEC Jinling Petrochemical Company,Nanjing 210046,China)

机构地区：[1]南京工业大学机械与动力工程学院,江苏南京211800 [2]南京工业大学高端装备可靠性制造研究院,江苏南京211800 [3]南京市锅炉压力容器检验研究院,江苏南京210019 [4]中国石化集团金陵石油化工有限责任公司,江苏南京210046

出　　处：《南京工业大学学报（自然科学版）》2024年第5期548-558,共11页Journal of Nanjing Tech University(Natural Science Edition)

基　　金：国家自然科学基金(51905261);国家自然科学基金联合基金重点支持项目(U21B2077)。

摘　　要：通过低周疲劳(LCF)和蠕变疲劳(CFI)试验,采用不同寿命预测模型,研究495℃下供货态以及服役30年2种状态下焦炭塔用20g钢的蠕变疲劳特性。LCF试验的应变幅值为±0.3%、±0.4%、±0.6%、±0.8%和±1.0%,CFI试验的保载时间最长可达30 min,保载形式包括拉伸、压缩以及拉压同时保载。结果表明:在低周疲劳试验条件下,相较于服役材料,供货态20g钢表现出更为明显的循环软化特性和应变幅值敏感性;长时服役并没有改变20g钢在蠕变疲劳载荷下的寿命变化规律,保载的引入均造成了2种材料循环寿命的减损,其中拉伸保载损伤最大,拉压保载次之,压缩保载影响最小,在拉伸保载30 min时,寿命减损程度最高可达73%,且相同保载条件下,供货态20g钢寿命减损程度更大。材料寿命预测分析结果表明:服役20g钢的预测寿命分散带高于供货态材料,延性耗竭法相较于时间分数法和修正应变能密度耗散法预测精度更高。The creep fatigue characteristics of 20g steel for coke towers in the supply state at 495℃and in the service state for 30 years were compared and investigated using low-cycle fatigue(LCF)and creep fatigue interaction(CFI)tests with different life prediction models.Strain amplitudes for the LCF test were±0.3%,±0.4%,±0.6%,±0.8%and±1.0%,while the holding time for the CFI tests could extend up to 30 min.Various strain holding modes,including tension,compression,and tension-compression were investigated.Results showed that under LCF loading the as-received 20g steel exhibited more pronounced cyclic softening characteristics and sensitivity to strain amplitudes compared to the material after long-term service,which did not change the life variation pattern of the steel under CFI loading.The introduction of strain holding induced a life reduction of both materials,with tension causing the largest damage,followed by tension-compression holding,and compression holding ranked the last.The life reduction reached up to 73%with 30 min of tensile loading.Additionally,as-received 20g steel exhibited more severe life reduction under the same loading conditions.Life prediction results indicated that the service-exposed 20g steel had a wider scatter in predicted life than the as-received material.Among the three prediction methods,the ductility exhaustion approach had the highest prediction accuracy,compared to the time fraction approach and the modified strain energy density exhaustion method.

关 键 词：20G钢 服役 低周疲劳 蠕变疲劳 疲劳寿命 寿命预测 

分 类 号：TH142[一般工业技术—材料科学与工程]