Microstructures and properties of heat affected zone for Q690q weathering bridge steel without preheating welding
PENG Ning-qi1, FU Gui-qin2, YANG Jian-hua1, ZHOU Wen-hao1, ZHU Miao-yong2
1. Technology and Quality Department, Hunan Valin Xiangtan Iron and Steel Co., Ltd., Xiangtan 411101, Hunan, China; 2. School of Metallurgy, Northeastern University, Shenyang 110819, Liaoning, China
Abstract：Using MMS-300 thermal simulation tester,the welding thermal cycle simulation tests were carried out for Q690q weather-resistant bridge steel. The microstructures,impact toughness and hardness of the coarse grained heat affected zone (CGHAZ),fine grained heat affected zone (FGHAZ) and inter-critical heat affected zone (ICHAZ) under the heat inputs of 10.5-114.9 kJ/cm were studied,and the morphology of the impact fractures were observed. Then,using the preferred welding heat input,the welding process evaluation tests of the preheat-free flux cored arc welding (FCAW),a metal inert-gas welding,and submerged arc welding (SAW) were carried out. Results show that when the heat input is low,CGHAZ and FGHAZ are mainly lath martensite,and ICHAZ appears as island-like M/A components,which make the impact toughness decrease and the hardness increase of these areas; when the heat input is high,CGHAZ is mainly large-sized granular bainite,quasi-upper bainite or upper bainite,while the large bulk M/A components increase and their sizes become larger,resulting in a significant decrease in impact toughness. At the same time,the higher heat input makes FGHAZ generate more high-temperature transformation microstructures of polygonal or quasi-polygonal ferrite and pearlite,the hardness of which is significantly reduced,and makes ICHAZ generate quasi-polygonal ferrite,carbide-free bainite and degraded pearlite,in addition to matrix microstructure of tempered sorbite,in which the carbide particle sizes become large,as a result,its strength and toughness decrease; when the heat input is 18.2-25.7 kJ/cm,CGHAZ is dominated by lath bainite with fine and heterotropic packets,FGHAZ form fine and uniform lath bainite and granular bainite,ICHAZ are mainly fine tempered sorbite and lath bainite,etc.,so that the three experimental sub-regions of heat affected zone obtain high impact toughness and hardness comparable to that of the base metal. Therefore,the preferred welding heat input should be controlled in the range of 18.2-25.7 kJ/cm. Using welding heat input of (22±1) kJ/cm,the developed 40 mm thick Q690q weather-resistant bridge steel plate has good weldability and welding performance for FCAW and SAW under preheat-free welding conditions,and the strength and toughness of the heat affected zone are not much different from the base metal. Thus it can be seen that the Q690q weather-resistant bridge steel was successfully tried in the laboratory to be preheat-free welded.
彭宁琦, 付贵勤, 杨建华, 周文浩, 朱苗勇. Q690q耐候桥梁钢免预热焊接热影响区的组织性能[J]. 钢铁, 2022, 57(12): 152-160.
PENG Ning-qi, FU Gui-qin, YANG Jian-hua, ZHOU Wen-hao, ZHU Miao-yong. Microstructures and properties of heat affected zone for Q690q weathering bridge steel without preheating welding[J]. Iron and Steel, 2022, 57(12): 152-160.
[1] QIN Shun-quan,GAO Zong-yu. Developments and prospects of long-span high-speed railway bridge technologies in China[J]. Engineering,2017(6):23. [2] Morozov Y D,Pemov I F,Matrosov M Y,et al. Steels for bridge structures[J]. Metallurgist,2020,63(12):933. [3] 陈焕德,刘东升. TMCP型Q500qENH特厚耐候桥梁钢板的工业试制[J]. 钢铁,2014,49(4):69.(CHEN Huan-de,LIU Dong-sheng. Industrial run to produce TMCP processed Q500qENH weathering heavy plate for bridge[J]. Iron and Steel,2014,49(4):69.) [4] 武凤娟,杨浩,曲锦波. 强化机制对高强度桥梁钢Q500qE屈强比的影响[J]. 中国冶金,2020,30(12):52. (WU Feng-juan,YANG Hao,QU Jin-bo. Effect of strengthening mechanism on yield ratio of high strength Q500qE bridge steel[J]. China Metallurgy,2020,30(12):52.) [5] 易伦雄,袁毅,彭最. 690 MPa级高性能桥梁钢工程应用[J]. 桥梁建设,2021,51(5):14. (YI Lun-xiong,YUAN Yi,PENG Zui. Engineering application of 690 MPa high-performance bridge steel[J]. Bridge Construction,2021,51(5):14.) [6] 彭宁琦,付贵勤,周文浩,等. 高强韧耐候桥梁钢Q690qNH的防断选材及验收方法[J]. 钢铁,2022,57(3):97. (PENG Ning-qi,FU Gui-qin,ZHOU Wen-hao,et al. Material selection and acceptance of fracture resistance for high strength and toughness weather-resistant bridge steel of Q690qNH[J]. Iron and Steel,2022,57(3):97.) [7] 郑凯锋,张宇,衡俊霖,等. 高强度耐候钢及其在桥梁中的应用与前景[J]. 哈尔滨工业大学学报,2020,52(3):1. (ZHENG Kai-feng,ZHANG Yu,HENG Jun-lin,et al. High strength weathering steel and its application and prospect in bridge engineering[J]. Journal of Harbin Institute of Technology,2020,52(3):1.) [8] Cano H,Diaz I,Fuente D D L,et al. Effect of Cu,Cr and Ni alloying elements on mechanical properties and atmospheric corrosion resistance of weathering steels in marine atmospheres of different aggressivities[J]. Materials and Corrosion,2018,69(1):8. [9] Chitoshi M,Atsushi I,Takashi K,et al. Proposal of new high performance steels for bridges (BHS500,BHS700)[J]. Doboku Gakkai Ronbunshu,2003,2003(738):1. [10] 周文浩. 高强韧耐候桥梁钢Q690qNH的不预热焊接试验[J]. 金属材料与冶金工程,2022,50(2):59. (ZHOU Wen-hao. Non-preheated welding test of Q690qNH high strength and toughness atmospheric corrosion resisting steel for bridge[J]. Metal Materials and Metallurgy Engineering,2022,50(2):59.) [11] 孟满丁,安同邦,魏金山,等. 690 MPa级ULCB熔敷金属组织与强韧化规律[J]. 钢铁,2022,57(2):149. (MENG Man-ding,AN Tong-bang,WEI Jin-shan,et al. Microstructure and strength-toughness mechanism of 690 MPa grade ULCB deposited metals[J]. Iron and Steel,2022,57(2):149.) [12] Park M H,Lee J P,Jin B J,et al. An experiment study for hardness characteristic of weldment according to welding heat-input of vertical GMA welding process[J]. Journal of Welding and Joining,2017,35(2):35. [13] 卓晓,安同邦,马成勇. 420 MPa级耐候桥梁钢用焊材熔敷金属强韧化规律[J]. 钢铁,2020,55(4):88. (ZHUO Xiao,AN Tong-bang,MA Cheng-yong. Strengthening and toughening mechanisms of deposited metals for 420 MPa weathering bridge steel[J]. Iron and Steel,2020,55(4):88.) [14] 刘素鹏,蒋有辉,李迁,等. 焊接热输入对Q690高强度桥梁钢焊接热影响区粗晶区组织与力学性能的影响[J]. 材料热处理学报,2020,41(2):153. (LIU Su-peng,JIANG You-hui,LI Qian,et al. Effect of welding heat input on microstructure and mechanical properties of coarse-grained welding heat-affected zone of Q690 high strength bridge steel[J]. Transactions of Materials and Heat Treatment,2020,41(2):153.) [15] Legault R A,Leckie H P. Effect of alloy composition on the atmospheric corrosion behavior of steels based on a statistical analysis of the Larrabee-Coburm data set[C]//ASTM STP 558:Corrosion in Natural Environments. Philadelphia:American Society for Testing and Materials,1974:334. [16] TONG Min,DI Xin-jie,LI Cheng-ning,et al. Toughening mechanism of inter-critical heat-affected zone in a 690 MPa grade rack plate steel[J]. Materials Characterization,2018,144:631. [17] Poorhaydari K,Patchett B M,Ivey D G. Estimation of cooling rate in the welding of plates with intermediate thickness[J]. Welding Journal,2005,84:159. [18] Kou S. Welding Metallurgy[M]. Hoboken:John Wiley and Sons,Inc,2020. [19] 张清清,章传国,郑磊. T8/5时间对X80管线钢热影响区组织和韧性的影响[J]. 中国冶金,2017,27(4):26. (ZHANG Qing-qing,ZHANG Chuan-guo,ZHENG Lei. Effect of T8/5 time on microstructure and toughness in heat affected zone of X80 pipeline steel[J]. China Metallurgy,2017,27(4):26.) [20] CHEN Zeng-tao,Butcher C. Micromechanics Modelling of Ductile Fracture[M]. Dordrecht:Springer,2013. [21] 郭锦,史佳新,陈雨来. 快速冷却前停留时间对微合金钢相变的作用[J].钢铁,2018,53(5):62. (GUO Jin,SHI Jia-xin,CHEN Yu-lai. Effect of delay time before rapid cooling on transformation of micro-alloyed steel[J]. Iron and Steel,2018,53(5):62.) [22] Zhao H,Wynne B P,Palmiere E J. Effect of austenite grain size on the bainitic ferrite morphology and grain refinement of a pipeline steel after continuous cooling[J]. Materials Characterization,2017,123:128. [23] WANG Xue-lin,WANG Zhi-quan,XIE Zhen-jia,et al. Combined effect of M/A constituent and grain boundary on the impact toughness of CGHAZ and ICCGHAZ of E550 grade offshore engineering steel[J]. Mathematical Biosciences and Engineering,2019,16(6):7494.
2022, Vol. 57 
