18CrNiMo7-6合金钢表面变质层准静态本构参数确定  

Determination of Dynamic Constitutive Parameters for 18CrNiMo7-6 Alloy Steel

作　　者：徐广涛[1] 李灿[1] 路留成 张悦[1] 王刚[1] 李凌霄 XU Guangtao;LI Can;LU Liucheng;ZHANG Yue;WANG Gang;LI Lingxiao(School of Mechanical and Power Engineering,Zhengzhou University,Zhengzhou 450001;School of Materials Science and Engineering,Zhengzhou University,Zhengzhou 450001)

机构地区：[1]郑州大学机械与动力工程学院,郑州450001 [2]郑州大学材料科学与工程学院,郑州450001

出　　处：《机械工程学报》2025年第6期184-193,共10页Journal of Mechanical Engineering

基　　金：国家自然科学基金(U1804254);国家资助博士后研究人员计划(GZC20232378);河南省重大科技专项(201400211200)资助项目。

摘　　要：基于逐层反演思想,提出一种确定表面变质层准静态本构参数的方法,使用该方法对渗碳热处理之后的18CrNiMo7-6合金钢表面变质层准静态本构参数进行确定。对基体样品进行渗碳热处理,使其表层微观结构发生改变形成表面变质层,进而对渗碳试样进行化学腐蚀剥层获取含有不同厚度表面变质层的圆棒试样。采用伺服疲劳试验机获取基体以及不同厚度表面变质层试样在25℃,应变率为0.0005s^(-1)下的应力应变关系。选用Johnson-Cook(J-C)本构模型,忽略应变率以及温度的影响,对18CrNiMo7-6合金钢的准静态力学性能进行描述,基于试验数据,结合遗传优化算法,确定表面变质层的J-C模型参数。结果表明,经过渗碳热处理后,试样的弹性模量没有展现出明显的差异,但其屈服强度以及抗拉强度明显增大。对表面变质层进行表征,给出了表面变质层的微观结构信息,从而揭示导致不同厚度表面变质层试样的力学性能展现出明显差异的物理本质。并通过有限元软件LS-DYNA对试样的准静态拉伸试验过程进行有限元模拟,验证了所得参数的可靠性,可为实际工程应用中的数值模拟计算问题提供重要依据。Based on the concept of layer-by-layer inversion,a method for determining the quasi-static constitutive parameters of the surface-modified layer of 18CrNiMo7-6 alloy steel after carburising heat treatment is presented.After carburizing,the surface microstructure of the matrix specimen changes and forms a surface-modified layer.The carburised specimen is subjected to chemical corrosion stripping to obtain a round rod specimen with different thicknesses of the surface-modified layer.The stress-strain relationships of matrix and surface-modified layer specimens with different thicknesses were obtained through a servo fatigue testing machine at 25℃and a strain rate of 0.0005 s^(-1).The Johnson-Cook(J-C)constitutive model was applied to describe the quasi-static mechanical properties of 18CrNiMo7-6 alloy steel while at the same time ignoring the influence of strain rate and temperature.The J-C model parameters of the surface-modified layer are determined based on the test data and genetic optimisation algorithm.Results show that after carburizing,the elastic modulus of the specimen does not show any evident difference,but there is a significant increase in the yield strength and tensile strength of the specimen.The surface-modified layer was characterized.The microstructure information of the surface-modified layer was elicited,which showed the physical nature that led to the evident differences in the mechanical properties of the surface-modified layer specimens with different thicknesses.The LS-DYNA finite element software was used to simulate the quasi-static tensile test process of the specimen.The reliability of the obtained parameters was verified.All these results provide an essential reference for numerical simulations in practical engineering applications.

关 键 词：18CrNiMo7-6合金钢 表面变质层 Johnson-Cook本构模型 拉伸试验 有限元模拟 

分 类 号：TG142[一般工业技术—材料科学与工程]