电焊机2025，Vol.55Issue(11)：72-81,10.DOI:10.7512/j.issn.1001-2303.2025.11.10
热输入对900 MPa级HSLA钢热影响组织和低温冲击韧性的影响
Effect of Heat Input on Heat-affected Organization and Low-Temperature Impact Toughness of 900 MPa grade HSLA
摘要
Abstract
To address the engineering challenges of microstructural heterogeneity and insufficient low-temperature impact toughness in the heat-affected zone(HAZ)of 900 MPa grade low-alloy high-strength steel(HSLA)welded joints,this study investigates the effects of different heat inputs on the HAZ microstructure,grain boundary characteristics,and low-temperature impact toughness for MAG joints used in engineering machinery.Analysis methods such as optical microscopy(OM),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and electron backscattered diffrac-tion(EBSD)were employed to observe and analyze the microstructural evolution of lath martensite(LM),lath bainite(LB),granular bainite(GB),and retained austenite within the HAZ.The results show that with increasing heat input from 12 kJ/cm to 21 kJ/cm,the bainite content in the HAZ gradually increases,austenite grains coarsen,the lath structure transitions from parallel to interwoven distribution,and the amount of retained austenite increases.Granular bainite appears when the heat input reaches a higher level.The content of high-angle grain boundaries(HAGBs)first increases and then decreases with heat input,peaking at 18 kJ/cm,effectively hindering crack propagation and significantly improving the joint's low-temperature impact toughness.Impact tests at-40℃reveal that the low-temperature impact energy absorption of the welded joints first rises and then falls with increasing heat input,peaking at 87.7 J at 18 kJ/cm.However,at 21 kJ/cm,due to grain coarsening and the emergence of granular bainite,the impact toughness noticeably decreases.This study provides important references for optimizing the process parameters of 900 MPa grade HSLA steel welded joints and enhancing their engineer-ing application performance.关键词
900 MPa级HSLA钢/热输入/热影响区/低温冲击韧性/大角度晶界Key words
HSLA steel/heat input/HAZ/low temperature impact toughness/large angle grain boundary分类
金属材料引用本文复制引用
安同邦,支晓洁,左月,曹志龙,王成,马成勇..热输入对900 MPa级HSLA钢热影响组织和低温冲击韧性的影响[J].电焊机,2025,55(11):72-81,10.基金项目
钢铁研究总院重点基金项目(21H62490Z) （21H62490Z）
