微合金钢价电子结构与力学性能关联的计算分析

Computational analysis of relationships between mechanical properties and microscopic valence electronic structures of microalloy steel

基于EET理论(固体与分子经验电子理论),以经淬火-分配-回火(Q-P-T)工艺热处理的微合金钢为研究对象,计算了其主要组成晶胞的价电子结构,提出表征微合金钢宏观力学性能的新参量:等效共价电子密度和键能统计值,并给出了准确定义及实验验证,从原子成键角度建立微合金钢各组成晶胞价电子结构相关参数与其强塑性的本质关联.研究表明:微合金钢中马氏体组元为硬脆相,对微合金钢力学性能主要起强化作用;奥氏体组元为塑软相,对微合金钢力学性能主要起韧化作用,而微合金钢表现出的宏观力学性能是其各组元晶胞的价电子结构参数与晶胞含量共同决定的结果.等效共价电子密度是其强度的表征,等效共价电子密度越大,微合金钢强度越大;而键能统计值是其塑性的表征,键能统计值越大,微合金钢塑性越大.

With microalloy steels treated by the quenching-partitioning-tempering（ Q-P-T） process as the research object,the valence electron structures of main phases were calculated on the basis of the empirical electron theory of solids and molecules,the equivalent covalent electron density and the statistics of bond energy were proposed as the representation of macroscopic mechanical properties,and their accurate definitions and experimental validation have been given,thus the internal relationships between strength and plasticity and microscopic valence electronic structures were established. The results show that martensite in microalloy steel is a hard brittle phase,which has the main reinforcement effect to mechanical properties. Austenite is the plastic soft phase,which has the main toughening effect to mechanical properties. However,the eventual macroscopic mechanical properties of microalloy steel are affected by both the valence electron structure parameters of unit cells and the percentages of them. The equivalent covalent electron density of microalloy steel is the characteristics of its strength. The bigger the equivalent covalent electron density is,the higher the strength of microalloy steel will be. While the statistics of the bond energy of microalloy steel is the characteristics of its toughness,the higher the statistics of bond energy is,the greater the micro alloy steel and plastic.