工程科学学报，第40卷，第1期：76-83,2018年1月 Chinese Journal of Engineering,Vol.40,No.I:76-83,January 2018 DOI:10.13374/j.issn2095-9389.2018.01.010;http://journals.ustb.edu.cn 基于应变控制的4Cr5 MoSiV1热作模具钢热机械疲劳 行为 左鹏鹏巴，吴晓春，曾艳，何西娟 上海大学材料科学与工程学院，上海200072 区通信作者，E-mail:p0513@163.com 摘要采用MTS®热机械疲劳电液伺服试验机研究了4C5 MoSiV1热作模具钢400~700℃范围内拉压对称机械应变控制的 同相及反相热机械疲劳行为.结果表明：当应变幅为±0.50%时，4C5 MoSiV1钢反相热机械疲劳寿命约为同相的60%：无论 同相还是反相加载，应力-应变滞后回线均呈现不对称性，同相加载时表现为平均压缩应力，反相加载时表现为平均拉伸应 力.两种加载方式下，最大应力与最大应变及峰值温度均不同步，在高温半周出现应力松弛现象.此外，高温半周呈现持续循 环软化，而低温半周呈现初始循环硬化，随后持续循环软化的特征.同相加载时断口以主裂纹、撕裂脊和准解理特征为主，裂 纹少而深：反相加载时断口以疲劳条纹和大量的凹坑特征为主，裂纹多而浅. 关键词热作模具钢：热机械疲劳：应变控制：应力应变行为：疲劳断口 分类号TG142.1 Strain-controlled thermal-mechanical fatigue behavior of 4Cr5MoSiV1 hot work die steel ZUO Peng-peng,WU Xiao-chun,ZENG Yan,HE Xi-juan School of Materials Science and Engineering,Shanghai University,Shanghai 200072,China Corresponding author,E-mail:zpp513@163.com ABSTRACT In-phase (IP)and out-of-phase (OP)thermal-mechanical fatigue (TMF)tests of 4Cr5MoSiVI hot work die steel were conducted in full reverse mechanical strain control in the temperature range of 400-700 C by a TMF servo-hydraulic testing system (MTS).The results indicate that,when the strain amplitude is 0.50%,the OP TMF life of 4Cr5MoSiVI steel is-60%of the IP TMF life.The stress-strain hysteresis loops show asymmetries for both IP and OP loading.IP loading leads to comprehensive mean stress,while OP loading gives rise to tensile mean stress in the temperature range of 400-700C.The changes of maximum strain and peak temperature with maximum stress are inconsistent,and the stress relaxation phenomenon could be observed under IP and OP load- ing.Moreover,two kinds of TMF cycling exhibite continuous cyclic softening in the high temperature half stage,while in the low tem- perature half stage,cyclic hardening occurs initially and is then followed by continuous cyclic softening.The fractured surfaces under IP TMF loading display striation and tear ridge,and exhibits quasi-cleavage characteristics.In addition,the cracks are less but longer. However,fractured surfaces under OP TMF loading mainly display striation and dimple characteristics,and the cracks are shorter and more abundant. KEY WORDS hot work die steel;thermal-mechanical fatigue;strain control;stress and strain behavior;fatigue fracture 收稿日期：2017-03-13 基金项目：国家重点研发计划资助项目(2016YFB0300400,2016YFB0300404)工程科学学报,第 40 卷,第 1 期:76鄄鄄83,2018 年 1 月 Chinese Journal of Engineering, Vol. 40, No. 1: 76鄄鄄83, January 2018 DOI: 10. 13374 / j. issn2095鄄鄄9389. 2018. 01. 010; http: / / journals. ustb. edu. cn 基于应变控制的 4Cr5MoSiV1 热作模具钢热机械疲劳 行为 左鹏鹏苣 , 吴晓春, 曾 艳, 何西娟 上海大学材料科学与工程学院, 上海 200072 苣通信作者,E鄄mail: zpp0513@ 163. com 摘 要 采用 MTS 襆 热机械疲劳电液伺服试验机研究了 4Cr5MoSiV1 热作模具钢 400 ~ 700 益范围内拉压对称机械应变控制的 同相及反相热机械疲劳行为. 结果表明:当应变幅为 依 0郾 50% 时,4Cr5MoSiV1 钢反相热机械疲劳寿命约为同相的 60% ;无论 同相还是反相加载,应力鄄鄄应变滞后回线均呈现不对称性,同相加载时表现为平均压缩应力,反相加载时表现为平均拉伸应 力. 两种加载方式下,最大应力与最大应变及峰值温度均不同步,在高温半周出现应力松弛现象. 此外,高温半周呈现持续循 环软化,而低温半周呈现初始循环硬化,随后持续循环软化的特征. 同相加载时断口以主裂纹、撕裂脊和准解理特征为主,裂 纹少而深;反相加载时断口以疲劳条纹和大量的凹坑特征为主,裂纹多而浅. 关键词 热作模具钢; 热机械疲劳; 应变控制; 应力应变行为; 疲劳断口 分类号 TG142郾 1 收稿日期: 2017鄄鄄03鄄鄄13 基金项目: 国家重点研发计划资助项目(2016YFB0300400,2016YFB0300404) Strain鄄controlled thermal鄄mechanical fatigue behavior of 4Cr5MoSiV1 hot work die steel ZUO Peng鄄peng 苣 , WU Xiao鄄chun, ZENG Yan, HE Xi鄄juan School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China 苣Corresponding author, E鄄mail: zpp0513@ 163. com ABSTRACT In鄄phase (IP) and out鄄of鄄phase (OP) thermal鄄mechanical fatigue (TMF) tests of 4Cr5MoSiV1 hot work die steel were conducted in full reverse mechanical strain control in the temperature range of 400鄄鄄 700 益 by a TMF servo鄄hydraulic testing system (MTS 襆 ). The results indicate that, when the strain amplitude is 依 0郾 50% , the OP TMF life of 4Cr5MoSiV1 steel is ~ 60% of the IP TMF life. The stress鄄鄄strain hysteresis loops show asymmetries for both IP and OP loading. IP loading leads to comprehensive mean stress, while OP loading gives rise to tensile mean stress in the temperature range of 400鄄鄄700 益 . The changes of maximum strain and peak temperature with maximum stress are inconsistent, and the stress relaxation phenomenon could be observed under IP and OP load鄄 ing. Moreover, two kinds of TMF cycling exhibite continuous cyclic softening in the high temperature half stage, while in the low tem鄄 perature half stage, cyclic hardening occurs initially and is then followed by continuous cyclic softening. The fractured surfaces under IP TMF loading display striation and tear ridge, and exhibits quasi鄄cleavage characteristics. In addition, the cracks are less but longer. However, fractured surfaces under OP TMF loading mainly display striation and dimple characteristics, and the cracks are shorter and more abundant. KEY WORDS hot work die steel; thermal鄄mechanical fatigue; strain control; stress and strain behavior; fatigue fracture