热处理工艺对780MPa级低碳贝氏体钢组织和性能的影响
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摘要
采用DIL805L型淬火膨胀仪测定了780 MPa级低碳贝氏体钢的连续冷却转变(CCT)曲线,研究了冷却速度对该钢组织转变和硬度的影响。结果表明:780 MPa级低碳贝氏体钢在冷却速度小于5℃·s~(-1)时,转变产物为贝氏体;当冷却速度大于5℃·s~(-1)时,转变产物中开始出现马氏体组织,且随着冷却速度的增加,马氏体逐渐增多,贝氏体逐渐减少;随着冷却速度的增加,试验钢的显微硬度逐渐增大,在冷却速度为5℃·s~(-1)时,硬度值有明显大幅度的增加;透射电镜分析结果显示冷却速度为5℃·s~(-1)时,在贝氏体组织内,位错堆积,并在晶界处最先形成马氏体。
The continuous cooling transformation(CCT)curves of 780 MPa grade low carbon bainitic steel were determined by DIL805 Lquenching dilatometer to study the effect of cooling rates on the microstructure transformation and hardness of the steel.The results show that for 780 MPa grade low carbon bainitic steel,when the cooling rate is lower than 5 ℃·s~(-1) the transformation product is bainite,and when the cooling rate is higher than 5℃·s~(-1),martensite structure begins to appeare in the transformation product.With the increase of cooling rate,the martensite increases gradually and the bainite decreases gradually.With the increase of cooling rate,the microhardness of the test steel increases gradually,and the hardness increases obviously at the cooling rate of5℃·s~(-1).Transmission electron microscope(TEM)analysis results show that when the cooling rate is 5 ℃·s~(-1),dislocation stacks in the bainite,and martensite first forms at the grain boundary.
The continuous cooling transformation(CCT)curves of 780 MPa grade low carbon bainitic steel were determined by DIL805 Lquenching dilatometer to study the effect of cooling rates on the microstructure transformation and hardness of the steel.The results show that for 780 MPa grade low carbon bainitic steel,when the cooling rate is lower than 5 ℃·s~(-1) the transformation product is bainite,and when the cooling rate is higher than 5℃·s~(-1),martensite structure begins to appeare in the transformation product.With the increase of cooling rate,the martensite increases gradually and the bainite decreases gradually.With the increase of cooling rate,the microhardness of the test steel increases gradually,and the hardness increases obviously at the cooling rate of5℃·s~(-1).Transmission electron microscope(TEM)analysis results show that when the cooling rate is 5 ℃·s~(-1),dislocation stacks in the bainite,and martensite first forms at the grain boundary.
引文
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[2]张健苹,王福明,曾强国,等.低碳贝氏体钢AH80DB过冷奥氏体连续冷却转变与等温转变[J].金属热处理,2014,39(3):89-93.
[3]尚成嘉,王学敏,杨善武,等.高强度低碳贝氏体钢的工艺与组织细化[J].金属学报,2003,39(10):1019-1024.
[4]张慧云,李艳梅.含硼低碳贝氏体钢的TMCP工艺模拟[J].金属热处理,2013,38(7):99-103.
[5]安治国,黄艳新,侯环宇,等.汽车前轴用贝氏体型非调质钢连续冷却转变[J].钢铁,2016,51(12):70-73.
[6]王丙兴,董福志,王昭东,等.超快冷条件下Mn-Nb-B系低碳贝氏体高强钢组织与性能研究[J].材料工程,2016(7):26-31.
[7]史远,黄胜永,安治国.冷却速率对30CrNiMo8钢过冷奥氏体转变的影响[J].理化检验(物理分册),2017,53(11):782-785.
[8]陈静,徐光,王凤琪,等.Fe-C-Mn-Si-Cr-V系超级贝氏体钢CCT曲线研究[J].热加工工艺,2013,42(20):70-72.
[9]张红梅,刘相华,王国栋,等.低碳贝氏体钢形变奥氏体的连续冷却相变研究[J].材料热处理学报,2000,21(4):35-40.
[10]谭谆礼,白秉哲,方鸿生.Mo在新型空冷低碳Mn-SiCr系贝氏体钢中的作用[J].金属热处理,2007,32(9):48-51.
[11]王香彬,韦弦,孙斌,等.含Mo低碳贝氏体钢形变奥氏体连续冷却相变规律研究[J].河南冶金,2011,19(2):16-18,47.
[12]MAHADEVAN S,GIRIDHAR A,SINGH A K.Calorimetric measurements on as-sb-se glasses[J].Journal of Non-Crystalline Solids,1986,88(1):11-34.
[13]OHMORI Y,JUNG Y C,NAKAI K,et al.Bainite transformation and the diffusional migration of bainite/austenite broad interfaces in Fe-9%Ni-Calloys[J].Acta Materialia,2001,49(16):3149-3162.