淬火-配分钢中残留奥氏体的演变及其对性能的影响
|
摘要
设计了一种含Cr型淬火-配分钢,利用热力学平衡原理计算了最佳淬火温度,研究了配分时间对微观组织演变和力学性能的影响。运用SEM和EBSD技术表征和统计分析了残留奥氏体的演变规律。试验结果表明:随淬火温度的升高,室温下残留奥氏体含量呈现先升高后降低的变化趋势,在205℃时达到最高值;随配分时间的延长,抗拉强度呈现降低的趋势,当配分时间由30 s延长到90 s,抗拉强度降低了165 MPa,而伸长率则呈现先升高后降低的趋势,在配分时间为60 s时,达到最高值17. 5%;随配分时间的延长,残留奥氏体的含量呈现先增加后降低的趋势。经880℃×5 min淬火至205℃+400℃×30 s处理后,残留奥氏体(111)_γ与马氏体(110)_α取向平行,符合K-S关系。
A quenching and partitioning steel containing Cr was designed. The optimal quenching temperature was calculated by using thermodynamic equilibrium theory. The influence of partitioning time on mechanical properties and microstructure were studied. The evolution of retained austenite was characterized by SEM and EBSD. The results indicate that the content of retained austenite has an increasing trend first and then decreases with the increasing quenching temperature,and has a peak value at 205 ℃. The tensile strength has a decreasing trend with the increasing partition time and has a reduction of 165 MPa with partitioning time extyending from 30 s to 90 s. The elongation has an increasing trend first and then decreases with the increasing time,and has the peak vale of 17. 5% at 60 s. The volume fraction of retained austenite has the same trend as elongation. The orientation of retained austenite( 111)_γ is parallel to that of martensite( 110)_α,and conforms to K-S relationship after austenitizing at 880 ℃ for 5 min,quenching to 205 ℃ and then partitioning at 400 ℃ for 30 s.
A quenching and partitioning steel containing Cr was designed. The optimal quenching temperature was calculated by using thermodynamic equilibrium theory. The influence of partitioning time on mechanical properties and microstructure were studied. The evolution of retained austenite was characterized by SEM and EBSD. The results indicate that the content of retained austenite has an increasing trend first and then decreases with the increasing quenching temperature,and has a peak value at 205 ℃. The tensile strength has a decreasing trend with the increasing partition time and has a reduction of 165 MPa with partitioning time extyending from 30 s to 90 s. The elongation has an increasing trend first and then decreases with the increasing time,and has the peak vale of 17. 5% at 60 s. The volume fraction of retained austenite has the same trend as elongation. The orientation of retained austenite( 111)_γ is parallel to that of martensite( 110)_α,and conforms to K-S relationship after austenitizing at 880 ℃ for 5 min,quenching to 205 ℃ and then partitioning at 400 ℃ for 30 s.
引文
[1]韩志勇,张明达,徐海峰,等.高性能汽车钢组织性能特点及未来研发方向[J].钢铁,2016,51(2):1-9.Han Zhiyong,Zhang Mingda,Xu Haifeng,et al.Research and application of high performance automobile steel[J].Iron and Steel,2016,51(2):1-9.
[2]魏元生.第三代高强度汽车钢的性能与应用[J].金属热处理,2015,40(12):34-39.Wei Yuansheng.Performance and application of the 3rd generation high strength automobile steel[J].Heat Treatment of Metals,2015,40(12):34-39.
[3]Speer J G,Edmonds D V,Rizzo F C,et al.Partition of carbon from supersaturated plates of ferrite,with application to steel processing and fundamentals of the bainite transformation[J].Current Opinion in Solid State and Materials Science,2004,8(34):218-237.
[4]Speer J G,Matlock D K,De Cooman B C,et al.Carbon partitioning into austenite after martensite transformation[J].Acta Materialia,2003,51(9):2611-2622.
[5]Paravicini Bagliani E,Santofimia M J.Microstructure,tensile and toughness properties after quenching and partitioning treatments of a medium-carbon steel[J].Materials Science and Engineering A,2013,559:485-495.
[6]Li H Y,L u X W,Wu X C,et al.Bainitic transformation during the two-step quenching and partitioning process in medium carbon steel containing Silicon[J].Materials Science and Engineering,A,2010,527:6254-6259.
[7]尹红霞,李辉,史春丽,等.奥氏体化温度对汽车用QP钢组织性能的影响[J].金属热处理,2017,42(11):108-111.Yin Hongxia,Li Hui,Shi Chunli,et al.Effect of austenitizing temperature on microstructure and mechanical properties of automotive QP steel[J].Heat Treatment of Metals,2017,42(11):108-111.
[8]朱国明,康永林,朱帅.汽车用超高强QP钢的工艺与组织性能研究[J].机械工程学报,2017,53(12):110-117.Zhu Guoming,Kang Yonglin,Zhu Shuai.Study on process,microstructure and property of ultra-high strength QP steel for automobile[J].Chinese Journal of Mechanical Engineering,2017,53(12):110-117.
[9]Speer J G,Streicher A M,Matlock D K,et al.Quenching and partitioning:A fundamentally new process to create high strength trip sheet microstructures[C]//Symposium on the Thermodynamics,Kinetics,Characterization and Modeling of:Austenite Formation and Decomposition.2003:505-522.
[10]Moor E D,Matlock D K,Speer J G,et al.Austenite stabilization through manganese enrichment[J].Scripta Materialia,2011,64(2):184-188.
[2]魏元生.第三代高强度汽车钢的性能与应用[J].金属热处理,2015,40(12):34-39.Wei Yuansheng.Performance and application of the 3rd generation high strength automobile steel[J].Heat Treatment of Metals,2015,40(12):34-39.
[3]Speer J G,Edmonds D V,Rizzo F C,et al.Partition of carbon from supersaturated plates of ferrite,with application to steel processing and fundamentals of the bainite transformation[J].Current Opinion in Solid State and Materials Science,2004,8(34):218-237.
[4]Speer J G,Matlock D K,De Cooman B C,et al.Carbon partitioning into austenite after martensite transformation[J].Acta Materialia,2003,51(9):2611-2622.
[5]Paravicini Bagliani E,Santofimia M J.Microstructure,tensile and toughness properties after quenching and partitioning treatments of a medium-carbon steel[J].Materials Science and Engineering A,2013,559:485-495.
[6]Li H Y,L u X W,Wu X C,et al.Bainitic transformation during the two-step quenching and partitioning process in medium carbon steel containing Silicon[J].Materials Science and Engineering,A,2010,527:6254-6259.
[7]尹红霞,李辉,史春丽,等.奥氏体化温度对汽车用QP钢组织性能的影响[J].金属热处理,2017,42(11):108-111.Yin Hongxia,Li Hui,Shi Chunli,et al.Effect of austenitizing temperature on microstructure and mechanical properties of automotive QP steel[J].Heat Treatment of Metals,2017,42(11):108-111.
[8]朱国明,康永林,朱帅.汽车用超高强QP钢的工艺与组织性能研究[J].机械工程学报,2017,53(12):110-117.Zhu Guoming,Kang Yonglin,Zhu Shuai.Study on process,microstructure and property of ultra-high strength QP steel for automobile[J].Chinese Journal of Mechanical Engineering,2017,53(12):110-117.
[9]Speer J G,Streicher A M,Matlock D K,et al.Quenching and partitioning:A fundamentally new process to create high strength trip sheet microstructures[C]//Symposium on the Thermodynamics,Kinetics,Characterization and Modeling of:Austenite Formation and Decomposition.2003:505-522.
[10]Moor E D,Matlock D K,Speer J G,et al.Austenite stabilization through manganese enrichment[J].Scripta Materialia,2011,64(2):184-188.