预热与焊后回火对铸钢基体双金属梯度堆焊锻模堆焊层组织与性能的影响
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摘要
为解决大型锻模的高成本、低寿命等问题,提出铸钢基体表面堆焊制备大型液压机用锻模新方法,针对其中的焊前预热与焊后回火工艺,将有限元分析与试验分析相结合,研究预热温度与焊后回火对堆焊层组织与力学性能的影响机理。研究结果表明:常温堆焊时,堆焊熔合区组织为马氏体+碳化物+残留奥氏体;随着预热温度的升高,冷却时间不断延长,组织呈现马氏体→贝氏体→珠光体转变趋势,显微硬度逐渐降低;当预热温度为400℃时,熔合区组织为铁素体+珠光体;焊后550℃/2 h回火后,堆焊层及热影响区硬度下降,基体中析出大量碳化物,堆焊层冲击韧性显著提高,断裂方式以韧窝断裂为主,母材性能在回火后无明显变化,说明预热与焊后热处理使堆焊层获得了较好的综合力学性能。
In order to solve the problems of high-cost and short life in large hydraulic press forging die, a new method, i.e. bimetal-gradient-layer surfacing(BGLS) based on cast-steel matrix cavity module, was adopted to manufacture hot forging die. The finite element method and experiment analysis were combined to investigate the effects of preheating and tempering on the microstructure and mechanical properties of the welds. The results show that when the specimen is preheated at room temperature, the microstructure is acircula martensite+carbides+retained austenite. As the preheating temperature increases, cooling time expands gradually, the microstructure has a trend of changing from martensite to bainite to pearlite and microhardness decreases. At 400 ℃, microstructure is mainly made up with ferrite+pearlite. After 550 ℃/2 h of tempering, the microhardness of surfacing layer and heat effect zone decreases, and large amounts of carbides precipitate in the matrix. The impact energy increases and the fracture mode is mainly dimple. Based material has no change in impact energy. In conclusion, pre and post weld heat treatments improve the mechanical properties of the welds.
In order to solve the problems of high-cost and short life in large hydraulic press forging die, a new method, i.e. bimetal-gradient-layer surfacing(BGLS) based on cast-steel matrix cavity module, was adopted to manufacture hot forging die. The finite element method and experiment analysis were combined to investigate the effects of preheating and tempering on the microstructure and mechanical properties of the welds. The results show that when the specimen is preheated at room temperature, the microstructure is acircula martensite+carbides+retained austenite. As the preheating temperature increases, cooling time expands gradually, the microstructure has a trend of changing from martensite to bainite to pearlite and microhardness decreases. At 400 ℃, microstructure is mainly made up with ferrite+pearlite. After 550 ℃/2 h of tempering, the microhardness of surfacing layer and heat effect zone decreases, and large amounts of carbides precipitate in the matrix. The impact energy increases and the fracture mode is mainly dimple. Based material has no change in impact energy. In conclusion, pre and post weld heat treatments improve the mechanical properties of the welds.
引文
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[15]PIAO Zhongyu,XU Binshi,WANG Haidou.Influence of surface nitriding treatment on rolling contact behavior of Fe-based plasma sprayed coating[J].Applied Surface Science,2013,266(2):420-425.
[16]XU W H,LIN S B,FAN C L.Evaluation on microstructure and mechanical properties of high-strength low-alloy steel joints with oscillating arc narrow gap GMA welding[J].The International Journal of Advanced Manufacturing Technology,2014,75(9/10/11/12):1439-1444.
[17]PESICKA J,KUZEL R,DRONHOFER A,et al.The evolution of dislocation density during heat treatment and creep of tempered martensite ferritic steels[J].Acta Mater,2003,51(16):4847-4862.
[18]PESICKA J,KUZEL R,DRONHOFER A,et al.Free dislocations and boundary dislocations in tempered martensite ferritic steels[J].Meter Sci Eng A,2004,387(1):176-180.
[19]WANG P,LU SP,XIAO N M.Effect of delta ferrite on impact properties of low carbon 13Cr-4Ni martensitic stainless steel[J].Mater Sci Eng,2010,527(13):3210-3216.
[2]周杰,曾强,罗艳.铸钢基体双金属梯度连接制备大型锻模的新方法研究进展[J].精密成形工程,2014,6(5):13-17,58.ZHOU Jie,ZENG Qiang,LUO Yan.Research progress in new approach for the manufacture of large forging die by gradient bimetallic connection on cast matrix[J].Journal of Netshape Forming Engineering,2014,6(5):13-17,58.
[3]KWON I K,KIM D S,PARK T D.Development of hot die forging process for large-size titanium alloy[J].Container Transactions of Materials Processing,2010,19(1):50-58.
[4]唐景富.堆焊技术及实例[M].北京:机械工业出版社,2010:1-21.TANG Jingfu,Surfacing welding technology and example[M].Beijing:China Machine Press,2010:1-21.
[5]周杰.一种基于铸钢基体的双层金属堆焊制备锻模的方法:中国,200910104604.X[P].2010-01-20.ZHOU Jie,A method for preparing forging die by bimetal-gradient-layer surfacing based on cast steel matrix.China,200910104604.X[P].2010-01-20.
[6]K?SE C,KA?AR R.The effect of preheat&post weld heat treatment on the laser weld ability of AISI 420 martensitic stainless steel[J].Materials and Design,2014,64:221-225.
[7]CHO S,KIM D H,AHN M Y.Development of low activation ferritic/martensitic steel welding technology for the fabrication of KO HCSB TBM[J].J Nucl Mater,2009,386/387/388(2):491-494.
[8]SCHELEV A.Microstructural evaluation of weld ability of cast steels considering the sensitivity to cold cracking[J].Materials Science&Engineering Technology,2003,34:109-114.
[9]ZHANG Jiansheng,ZHOU Jie,TAO Yaping.The microstructure and properties change of dies manufactured by bimetal-gradientlayer surfacing technology[J].The International Journal of Advanced Manufacturing Technology,2015,80(9/10/11/12):1807-1814.
[10]卢顺,周杰,曾强.基于数值模拟的铸钢基体堆焊锻模焊层厚度优化[J].华南理工大学学报(自然科学版),2014,42(3):84-89,124.LU Shun,ZHOU Jie,ZENG Qiang.Numerical simulation-based optimization of welding thickness of forging die manufactured by steel casting surfacing[J].Journal of South China University of Technology,2014,42(3):84-89,124.
[11]LU S,ZHOU J,ZHANG J.Optimization of welding thickness on casting-steel surface for production of forging die[J].The International Journal of Advanced Manufacturing Technology,2015,76(5/6/7/8):1411-1419.
[12]卢顺,周杰,李梦瑶,等.基于数值模拟的铸钢基体表面堆焊模具组织与性能研究[J].热加工工艺,2013,42(19):19-20,25.LU Shun,ZHOU Jie,LI Mengyao,et al,Research on mold microstructure and properties of welding on casting-steel based on numerical simulation[J].Hot Working Technology 2013,42(19):19-20,25.
[13]兰亮云,邱春林,赵德文,等.低碳贝氏体钢焊接热影响区中不同亚区的组织特征与韧性[J].金属学报,2011,47(8):1046-1054.LAN Liangyun,QIU Chunyun,ZHAO Dewen,et al.Microstructural characters and toughness of different sub-regions in the welding heat affected zone of low carbon bainitic steel[J].Acta Metallurgica Sinica,2011,47(8):1046-1054.
[14]周野飞,韩超,杨庆祥,等.马氏体相变对堆焊冷却切向应力影响的数值模拟[J].焊接学报,2012,33(2):73-76.ZHOU Yefei,HAN Chao,YANG Qingxiang,et al.Process stress field simulation of hot rolled steel specimen after hard face-welding[J].Transactions of the China Welding Institution,2012,33(2):73-76.
[15]PIAO Zhongyu,XU Binshi,WANG Haidou.Influence of surface nitriding treatment on rolling contact behavior of Fe-based plasma sprayed coating[J].Applied Surface Science,2013,266(2):420-425.
[16]XU W H,LIN S B,FAN C L.Evaluation on microstructure and mechanical properties of high-strength low-alloy steel joints with oscillating arc narrow gap GMA welding[J].The International Journal of Advanced Manufacturing Technology,2014,75(9/10/11/12):1439-1444.
[17]PESICKA J,KUZEL R,DRONHOFER A,et al.The evolution of dislocation density during heat treatment and creep of tempered martensite ferritic steels[J].Acta Mater,2003,51(16):4847-4862.
[18]PESICKA J,KUZEL R,DRONHOFER A,et al.Free dislocations and boundary dislocations in tempered martensite ferritic steels[J].Meter Sci Eng A,2004,387(1):176-180.
[19]WANG P,LU SP,XIAO N M.Effect of delta ferrite on impact properties of low carbon 13Cr-4Ni martensitic stainless steel[J].Mater Sci Eng,2010,527(13):3210-3216.