1000MPa级水电钢SH-CCT曲线测定与冷裂敏感性分析  

SH-CCT Curve Determination and Cold Crack Sensitivity Analysis of 1000MPa Hydropower Steel

作　　者：张奎良 李景[1,2] 李海军 吴海龙 甘洪丰[1,2] ZHANG Kuiliang;LI Jing;LI Haijun;WU Hailong;GAN Hongfeng(Harbin Electric Machinery Company Limited,Harbin 150040,China;State Key Laboratory of Hydro-Power Equipment,Harbin 150040,China;China Three Gorges Construction Engineering Corporation,Chengdu 160000,China)

机构地区：[1]哈尔滨电机厂有限责任公司,哈尔滨150040 [2]水力发电设备全国重点实验室,哈尔滨150040 [3]中国三峡建工(集团)有限公司,成都610000

出　　处：《大电机技术》2024年第5期81-87,共7页Large Electric Machine and Hydraulic Turbine

基　　金：黑龙江省自然科学基金(YQ2021E007);黑龙江省青年科技人才托举工程项目(2023QNTJ013)。

摘　　要：本文采用模拟焊接热循环方法研究了1000MPa级高强钢焊接粗晶热影响区组织和性能的演化规律,并对该钢的冷裂纹敏感性进行了评价,最终为该钢在工程实践应用中的焊接工艺合理制定提供理论和试验依据。利用Gleeble-3800开展1000MPa级水电高强钢焊接热模拟试验,结合组织观察和硬度测试结果,绘制了研究用钢在不同冷却速率条件下的焊接连续冷却转变曲线(SH-CCT)。随冷却速率增加,粗晶热影响区组织由中温贝氏体组织逐渐向低温马氏体组织转变,组织中M-A组元数量下降,形态也由长条状和大块状混合态逐渐转变为弥散分布的小颗粒态。热影响粗晶区硬度随t_(8/5)冷却时间缩短而呈升高趋势,当t_(8/5)≤15s时,研究用钢粗晶区具有较高淬硬倾向,当t_(8/5)>60s时,粗晶区硬度发生软化。冷裂纹敏感性评价和Y型坡口试验表明,试验钢碳当量Ceq大于0.5%,具有一定的冷裂倾向,需焊前预热,预热温度75℃以上可避免焊接热影响区内冷裂纹发生。In this paper,the evolution of microstructure and properties of coarse-grained heat affected zone(HAZ)of 1000MPa grade high strength steel was studied by using simulated welding heat cycle method,which provided theoretical and experimental basis for the reasonable development of welding technology for the steel in engineering applications.The welding thermal simulation experiment of 1000MPa hydroelectric high-strength steel was carried out by using Gleeble-3800.Combined with the microstructure observation and hardness test results,the welding continuous cooling transition curve(SH-CCT)was drawn at different cooling rates,and the effect of cooling rate on the microstructure and hardness of the welding coarse-grained region was studied.The microstructure of coarse-grained region changes from medium-temperature bainite to low-temperature martensite gradually,the number of M-A components decreased,and the morphology gradually changed from the mixed state of long strips and large bulks to the dispersed small particles with the increase of cooling rate.The hardness of coarse-grained region increases with the shortening of t_(8/5)cooling time.When t_(8/5)≤15s,the coarse-grained region has a higher hardening tendency,and when t_(8/5)>60s,the hardness of coarse-grained region softens.Cold crack sensitivity evaluation and Y-groove test show that the carbon equivalent Ceq of the studied steel is greater than 0.5%,and it has a certain tendency to cold crack,so it needs to be preheated before welding.The preheating temperature above 75℃can avoid cold crack in the welding heat affected zone.

关 键 词：1000MPa SH-CCT曲线 粗晶热影响区 显微组织 冷裂敏感性 水电钢 

分 类 号：TK730.5[交通运输工程—轮机工程] TG142.1[动力工程及工程热物理—流体机械及工程]