基于微结构损伤的珠光体材料本构行为研究

A MICROSTRUCTURE-BASED DAMAGE CONSTITUTIVE MODEL FOR PEARLITIC MATERIALS

珠光体材料由许多随机取向的珠光体团组成,每一珠光体团又由铁素体片和渗碳体片交替叠合而成．实验表明具有较小片层间距的珠光体材料具有较高的强度和寿命．通过分析构成珠光体团的各相及界面的损伤特征,利用损伤耗散功的概念,得到了铁素体、渗碳体与界面损伤的具有统一形式的演化规律,将其嵌入基于细片层微结构和非经典塑性理论的珠光体团的弹塑性本构方程,利用Hill自洽方法,得到了珠光体材料的损伤本构描述．所得到的损伤本构描述显含表征微结构特征的片层间距,容易证明具有较小片层间距的珠光体材料具有较好的综合力学性能．对珠光体材料的拉伸和循环拉压特性进行了分析,得到了与实验一致的结果．

Based on the laminar microstructure formed by ferrite and cementite with very fine interlamellar spacing, and the morphology of microdefects in the ferrite, cementite and interface, a unified damage evolution is proposed by making use of the work dissipated on damage. It is then embedded in the constitutive model of each phase and a damage elastoplastic constitutive model is obtained for a single pearlitic colony. The damage constitutive description for pearlitic materials is formulated using the Hill＇s self-consistent scheme by assuming that a pearlitic material element is an aggregate of numerous cells of pearlitic colonies with randomly distributed orientations. It is significant that the obtained constitutive description contains exphcitly the interlamellar spacing as a microstructure parameter, which easily accounts for the better comprehensive mechanical properties of the pearlitic materials with smaller interlamellar spacing. The constitutive behavior of pearlitic steel is simulated, and compared with the experimental results.