选区激光熔化24CrNiMoY合金钢组织与强韧性的匹配关系

Matching relationship between microstructure and strength-toughness of 24CrNiMoY alloy steel by laser additive manufacturing

基于选区激光熔化(SLM)技术制备强韧性匹配合金钢高铁制动盘应用需求,文中采用全自动SLM成形系统制备24CrNiMoY合金钢样品,通过研究81~111 J/mm^(3)不同能量密度对合金钢样品的微观组织与力学性能的影响,揭示合金钢样品组织与强韧性的匹配关系。研究结果表明:激光能量密度对成形合金钢样品的组织与性能具有重要影响,样品微观组织主要由下贝氏体与粒状贝氏体及少量铁素体组成;当激光能量密度为89 J/mm^(3)时,制备的SLM 24CrNiMoY合金钢样品具有最优的强韧性匹配关系,样品显微组织中下贝氏体、粒状贝氏体与铁素体含量分别为88%,11%与1%,其抗拉强度为1234 MPa,断后伸长率为9.2%,强塑积为11.4 GPa%。制备样品具有强韧性匹配的主要决定因素是形成了均匀的不同比例的下贝氏体与粒状贝氏体及铁素体等组织,通过调控激光能量密度,获得尽可能多的下贝氏体组织,11%~15%的粒状贝氏体组织与1.5%以下的铁素体组织时,能够制备出具有高强韧性的SLM 24CrNiMoY合金钢样品。该方法为SLM制备具有良好强韧性匹配的24CrNiMoY制动盘样品提供了重要参考。

Based on the application requirements of selective laser melting(SLM)technology for the preparation of high strength-toughness matching alloy steel brake discs,this paper adopted automatic SLM forming system to prepare 24CrNiMoY alloy steel samples,which revealed the matching relationship between microstructure and strength-toughness of SLM 24CrNiMoY by studying the effects of the laser energy densities(81~111 J/mm^(3))on the microstructure and mechanical properties.The results showed that the laser energy density had an important influence on the microstructure and mechanical properties of the SLM 24CrNiMoY alloy steel samples,whose the microstructure was mainly consisted of lower bainite,granular bainite and a small amount of ferrite.When the laser energy density was 89 J·mm^(-3),the SLM24CrNiMoY alloy steel samples had the optimal strength-toughness matching relationship,the contents of lower bainite,granular bainite and ferrite in the microstructure of the sample were 88%,11% and 1% respectively.Meanwhile,the SLM sample exhibited the best mechanical properties with the tensile strength of 1234 MPa,elongation after break of9.2% and the product of strength and elongation of 11.4 GPa%.The main determinant of the strength-toughness matching properties of the SLM 24CrNiMoY samples was the different ratios of lower bainite,granular bainite and ferrite.It was found that adjusting the laser energy density to obtain as much lower bainite as possible,11%~15% granular bainite and less than 1.5% ferrite could successfully prepare high strength-toughness SLM 24CrNiMoY alloy steel samples.This method provided an important reference for prepare high strength-toughness SLM 24CrNiMoY brake disc alloy steel samples.