轨道车辆转向架用Q690耐候钢的焊接接头性能  

Welded joint properties of Q690 weathering steel for railcar bogies

作　　者：刘悦 郑晓明 李秋明 杜林秀[2] 杨志南[3] LIU Yue;ZHENG Xiaoming;LI Qiuming;DU Linxiu;YANG Zhinan(Mechanical Engineering,North China University of Science and Technology,Tangshan 063210,Hebei,China;The State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,Liaoning,China;State Key Laboratory of Metastable Materials Science and Technology,Yanshan University,Qinhuangdao 066004,Hebei,China)

机构地区：[1]华北理工大学机械工程学院,河北唐山063210 [2]东北大学轧制技术及连轧自动化国家重点实验室,辽宁沈阳110819 [3]燕山大学亚稳材料制备技术与科学国家重点实验室,河北秦皇岛066004

出　　处：《钢铁》2024年第10期77-85,106,共10页Iron and Steel

基　　金：国家自然科学基金资助项目(52374406,52122410)。

摘　　要：为了保障Q690高强耐候钢焊接的优质,确保焊接接头拥有出色的韧性,对其性能进行研究以推动其在轨道车辆转向架领域的广泛应用,更好地实现产品的升级换代。采用混合气体(80%Ar和20%CO_(2))保护焊对轨道车辆转向架用Q690耐候钢进行了10 kJ/cm和20 kJ/cm两种线能量的对焊焊接试验。利用金相显微镜和透射电子显微镜对气体保护焊焊接接头的微观组织进行观察,并运用冲击试验仪和显微硬度计来测定焊接接头各个区域的力学性能,从而研究焊接线能量、组织结构和力学性能之间的相互关系。这些试验结果为理解焊接接头的内部结构和力学性能提供了重要参考,有助于优化焊接工艺和提高焊接接头的质量和性能。结果表明,该气体保护焊接试验采用免焊前预热和焊后热处理措施,焊缝主要由大量纵横交错的针状铁素体和多边形先共析铁素体构成;在线能量为10 kJ/cm时,焊缝、熔合线、熔合线向外1 mm、熔合线向外3 mm处-20℃冲击功分别为75.2、56.4、69.6、123.4 J,焊接接头的显微硬度为279HV~312HV,粗晶区、细晶区和临界区为局部硬化区;当焊接接头的线能量提高至20 kJ/cm时,显微硬度相较于10 kJ/cm有所降低,增大的线能量会导致焊接接头发生一定程度的软化。V(C,N)析出相会通过促进针状铁素体的形核,使得纵横交错的针状铁素体之间能够更好地咬合,从而有效抑制裂纹的扩展,进而提高材料的冲击韧性。细晶区中均匀分布着大量细小的等轴晶,能够通过细晶强化及高角度晶界韧化机制改善低温冲击韧性。研究结果为制定合理的焊接工艺和轨道车辆转向架用钢的断裂安全评定奠定基础。In order to ensure the high quality of Q690 high strength weathering steel welding and ensure that the welded joints have excellent toughness,the properties were studied,so as to promote its wide application in the field of railcar bogies and better realize the upgrading of products.An experimental study was conducted on Q690 weathering steel for railcar bogies,focusing on butt welding with two different line energies of 10 kJ/cm and 20 kJ/cm.The welding process utilized a mixed gas shield of 80%Ar and 20%CO_(2).The microstructure of gas shielded welding joints was observed using metallographic microscope and transmission electron microscope,and the mechanical properties of each area of the welded joint were measured using impact tester and micro-hardness tester,in order to study the relationship between welding line energy,microstructure,and mechanical properties.These experimental results provide important references for understanding the internal structure and mechanical properties of welded joints,helping to optimize welding processes and improve the quality and performance of welded joints.The results indicated that preheating and post-welding heat treatment was unnecessary in this gas-shielded welding process.The weld primarily consisted of a significant amount of crisscross acicular ferrite and polygonal pro-eutectoid ferrite.At a line energy of 10 kJ/cm,the impact energy at-20℃of the weld,fusion line,1 mm outward of the fusion line,and 3 mm outward of the fusion line were measured at 75.2,56.4,69.6,and 123.4 J,respectively.The micro-hardness of the welded joint ranged from 279HV to 312HV,with local hardening zones observed in the coarse grain zone,fine grain zone,and critical zone.When the heat input of welded joint increased to 20 kJ/cm,the micro-hardness decreased compared with 10 kJ/cm,and the increase of heat input would cause the softening of welded joint to some extent.V(C,N)precipitates could promote the nucleation of acicular ferrite,so that the crisscross acicular ferrite could be better engage

关 键 词：耐候钢 气体保护焊 Q690 焊接接头 断口形貌 

分 类 号：U270.33[机械工程—车辆工程] TG407[交通运输工程—载运工具运用工程]