工艺参数对SWRCH35KM组织与力学性能的影响
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摘要
以实现免退火冷镦钢SWRCH35KM在线软化处理为目标,研究了变形和冷却工艺制度对中碳冷镦钢组织演变和力学性能的影响。结果表明,采用分段缓冷制度,850~750℃终轧后均获得体积分数为60%~63%的铁素体加部分球化珠光体,随着终轧温度降低,铁素体量略有增加,晶粒尺寸从15~16.9μm细化至约10μm,珠光体球化趋势趋于显著。冷却制度对于实验钢力学性能有显著影响。采用轧后分段缓冷制度后,抗拉强度约为490~510MPa,伸长率为36.5%~40.5%,洛氏硬度为73HRB~78HRB;与直接空冷工艺相比,不同终轧温度下抗拉强度降低约为30~40MPa,伸长率提高1%~3%,洛氏硬度降低2HRB~3HRB。
In order to realize the on-line softening treatment of non-annealed cold heading steel SWRCH35 KM,the influence of controlled rolling and controlled cooling process on the microstructure and mechanical properties of medium carbon cold heading steel was investigated.The results show that the microstructures of spherular pearlite dispersed in 60%-63% ferrite matrix are obtained after step slow cooling process.With the decrease of finish rolling temperature from 850℃to 750℃,ferrite grain size refines from 15-16.9μm to about 10μm,and spheroidization of pearlite tends to significantly.Tensile strength of test steel with step slow cooling process is about490-510 MPa,elongation is 36.5%-40.5%,and hardness is 73 HRB-78 HRB.Compared with the air cooling process,the tensile strength of test steel decreases by about 30-40 MPa,elongation increases by 1%-3% and hardness decreases by about 2 HRB-3 HRB.
In order to realize the on-line softening treatment of non-annealed cold heading steel SWRCH35 KM,the influence of controlled rolling and controlled cooling process on the microstructure and mechanical properties of medium carbon cold heading steel was investigated.The results show that the microstructures of spherular pearlite dispersed in 60%-63% ferrite matrix are obtained after step slow cooling process.With the decrease of finish rolling temperature from 850℃to 750℃,ferrite grain size refines from 15-16.9μm to about 10μm,and spheroidization of pearlite tends to significantly.Tensile strength of test steel with step slow cooling process is about490-510 MPa,elongation is 36.5%-40.5%,and hardness is 73 HRB-78 HRB.Compared with the air cooling process,the tensile strength of test steel decreases by about 30-40 MPa,elongation increases by 1%-3% and hardness decreases by about 2 HRB-3 HRB.
引文
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[4]Tian Y L,Kraft R W.Mechanisms of pearlite spheroidization[J].Metallurgical Transactions,1987,18A(8):1403.
[5]Zhao P,Boyd J D.Microstructural evolution during thermomechanical processing of microalloyed medium carbon steels[J].Materials Science and Technology,2003,19(11):1557.
[6]Hideo H,Hiroshi Y,Masataka S,et al.Development of high quality wire rod through thermo mechanical control process[J].Kobelco Technology Review,2002(25):25.
[7]Lee D L,Lee Y H,Choi J K,et al.The effect of SIDT on the microstructure of medium carbon steel[C]//Proceeding of the4th workshop on HIPERS-21.Pohang,Korea:2002.
[8]刘小林.变形工艺对低碳钢奥氏体中析出物的影响[J].钢铁研究,2007,35(1):23.(Liu X L.Effect of deforming processing on the precipitation of carbonitride in austenite structure[J].Research on Iron and Steel,2007,35(1):23.)
[9]张怀宇,惠卫军,董瀚,等.简化42CrMo钢球化退火工艺的研究[J].钢铁研究学报,2007,19(3):62.(Zhang H Y,Hui W J,Dong H,et al.Simplified spheroidizing annealing process of 42CrMo steel[J].Journal of Iron and Steel Research,2007,19(3):62.)
[10]惠卫军,田鹏,董翰,等.形变温度对中碳钢组织转变的影响[J].金属学报,2005,41(6):611.(Hui W J,Tian P,Dong H,et al.Influence of deformation temperatures on the microstructure transformation in medium carbon steel[J].Acta Metallurgica Sinica,2005,41(6):611.)