铸造技术2026，Vol.47Issue(8)：926-935,10.DOI:10.16410/j.issn1000-8365.2026.5258
G20Mn5QT低合金铸件缺欠的焊补工艺研究
Study on the Welding Repair Process for G20Mn5QT Low-alloy Casting Steel
摘要
Abstract
A systematic investigation was conducted on an advanced weld repair methodology aimed at rectifying casting defects in critical components,specifically brake calliper brackets manufactured from G20Mn5QT low-alloy cast steel,which are employed in rail transit systems.The primary goal is to improve the quality of defect remediation and enhance the operational reliability of these components.G20Mn5QT,a low-alloy cast steel widely used in vital load-bearing structures such as bogies and braking mechanisms,is prone to casting imperfections,including porosity,slag inclusions,and cracking,largely attributable to process variability.These defects substantially undermine the service life and safety performance of the components.Welding repair constitutes a pivotal approach to address these flaws,thereby lowering production expenses and optimizing material usage.However,the relatively elevated carbon equivalent of G20Mn5QT(ranging from 0.48～0.64),coupled with its predominantly martensitic microstructure,predisposes the welding process to challenges such as embrittlement within the heat-affected zone,cold cracking,and residual stress accumulation,necessitating stringent control over the welding parameters.On this basis,shielded metal arc welding(SMAW)utilizing the low-hydrogen,high-toughness electrode ESAB OK48.04 was employed to systematically evaluate the effects of critical welding parameters,including preheating temperature,interpass temperature,and heat input,on the microstructural characteristics and mechanical performance of the welded joints.Comprehensive assessments were conducted through mechanical testing,hardness profiling,and metallographic examination.The findings reveal that under optimized conditions,specifically,preheating at(200±10)℃,interpassing temperatures between 210 and 300℃,and heat inputs ranging from 1.0 to 1.8 kJ/mm,the weld repairs achieve tensile strengths exceeding 571 MPa,fracture elongations of no less than 27％,and Charpy impact energies at-40℃ reaching up to 130 J.The hardness distribution across the weld metal and heat-affected zone is uniform,with continuous microstructural transitions and an absence of defects such as cracks or porosity.The optimization of the weld repair process facilitates the high-quality restoration of casting defects in G20Mn5QT cast steel,yielding joint strengths comparable to those of the base material and significantly improving the low-temperature toughness.关键词
低合金铸钢/焊补/热影响区脆化/残余应力控制/工艺评定Key words
low-alloy cast steel/welding repair/heat-affected zone embrittlement/residual stress control/process qualification分类
矿业与冶金引用本文复制引用
马凯,边惠惠,魏晓,高志雄,肖骞,李剑波..G20Mn5QT低合金铸件缺欠的焊补工艺研究[J].铸造技术,2026,47(8):926-935,10.基金项目
中国兵器工业集团科技研究开发计划(JM220624) （JM220624）
