加热过程中H_2O(g)对55SiCr弹簧钢脱碳的影响
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摘要
设计了气氛混合装置,控制炉气成分以及H2O(g)含量,利用真空管式加热炉对弹簧钢铸坯试样进行加热保温。采用激光多点共聚焦显微镜研究了混合气氛下H2O(g)对弹簧钢表面脱碳的影响。结果表明,试样总脱碳层厚度随温度升高而增加;混合气氛下,650℃出现轻微铁素体脱碳,700～950℃有明显铁素体脱碳层,850℃为铁素体脱碳峰值温度,与空气条件相比,表面铁素体脱碳更加严重,脱碳开始温度有所降低。低温区表面脱碳的发生与C浓度梯度驱动下珠光体片层中渗碳体的溶解有关,铁素体脱碳层晶粒形态呈现为尺寸细小、无明显取向。H2O(g)破坏防止脱碳的保护机制,对试样脱碳程度的加深有重要作用。
Spring steel is an important steel widely used in the national economic construction. Its application environment is quite harsh, so it strongly demands for a high quality of the surface. However,the decarburization behavior on the surface seriously affects the surface quality and reduces the fatigue performance of materials. Decarburization is caused by chemical reaction between oxidizing atmosphere and steel surface. Hydrosphere, as a component of the oxidizing atmosphere, could lead to a significant influence on decarburization process. Our experimental materials, taken from continuous casting billet,were polished carefully by abrasive paper in order to remove stains, original scale and decarburization layer. Components of furnace gas were controlled by mixing units designed independently. Spring steel samples were heated by a tube vacuum furnace in 600～950 ℃. The mixed atmosphere contains(15%～20%)CO2,(2%～4%)O2, hydrosphere of different contents and N2 in balance. With the condition of the mixed atmosphere, influence of hydrosphere on surface decarburization of spring steel 55 SiCr was investigated by 3 D measuring laser microscope. The results show that, with the influence of the mixed atmosphere, decarburization is able to happen during low temperature interval, 650 ℃～Ac1(Ac1: starting temperature of austenitization during slow heating). The thickness of total decarburized layer increases correspondingly with the temperature. In the mixed atmosphere, slight decarburization occurs at 650 ℃ and obvious ferrite decarburization layer can be detected within a temperature range of 700～950 ℃, which is more serious than that in the air. The peak temperature of ferrite decarburization is 850 ℃ under both mixed atmosphere and air.The surface decarburization in low temperature region is related to the dissolution of cementite in pearlite lamellae driven by carbon concentration gradient.When the decarburization degree deepens as time goes,partial pearlite colony begins to shrink,much line form cementite dissolves gradually,and the line cementite becomes short and punctate.The grain morphology of ferrite decarburization layer is different from that who generates within a+g phase region,which is small in size and without a strong orientation.Hydrosphere in mixed atmosphere could increase porosity of oxidation layer and destroy the important protection mechanism of preventing decarburization by compact scale.It is deduced that existing of hydrosphere offers a chance for low temperature decarburization process occurring and hydrosphere plays an important role in deepening the decarburization degree of samples.
Spring steel is an important steel widely used in the national economic construction. Its application environment is quite harsh, so it strongly demands for a high quality of the surface. However,the decarburization behavior on the surface seriously affects the surface quality and reduces the fatigue performance of materials. Decarburization is caused by chemical reaction between oxidizing atmosphere and steel surface. Hydrosphere, as a component of the oxidizing atmosphere, could lead to a significant influence on decarburization process. Our experimental materials, taken from continuous casting billet,were polished carefully by abrasive paper in order to remove stains, original scale and decarburization layer. Components of furnace gas were controlled by mixing units designed independently. Spring steel samples were heated by a tube vacuum furnace in 600～950 ℃. The mixed atmosphere contains(15%～20%)CO2,(2%～4%)O2, hydrosphere of different contents and N2 in balance. With the condition of the mixed atmosphere, influence of hydrosphere on surface decarburization of spring steel 55 SiCr was investigated by 3 D measuring laser microscope. The results show that, with the influence of the mixed atmosphere, decarburization is able to happen during low temperature interval, 650 ℃～Ac1(Ac1: starting temperature of austenitization during slow heating). The thickness of total decarburized layer increases correspondingly with the temperature. In the mixed atmosphere, slight decarburization occurs at 650 ℃ and obvious ferrite decarburization layer can be detected within a temperature range of 700～950 ℃, which is more serious than that in the air. The peak temperature of ferrite decarburization is 850 ℃ under both mixed atmosphere and air.The surface decarburization in low temperature region is related to the dissolution of cementite in pearlite lamellae driven by carbon concentration gradient.When the decarburization degree deepens as time goes,partial pearlite colony begins to shrink,much line form cementite dissolves gradually,and the line cementite becomes short and punctate.The grain morphology of ferrite decarburization layer is different from that who generates within a+g phase region,which is small in size and without a strong orientation.Hydrosphere in mixed atmosphere could increase porosity of oxidation layer and destroy the important protection mechanism of preventing decarburization by compact scale.It is deduced that existing of hydrosphere offers a chance for low temperature decarburization process occurring and hydrosphere plays an important role in deepening the decarburization degree of samples.
引文
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[2] Choi S, van der Zwaag S. Prediction of decarburized ferrite depth of hypoeutectoid steel with simultaneous oxidation[J]. ISIJ Int., 2012,52:549
[3] Zhao X J, Guo J, Wang H Y, et al. Effects of decarburization on the wear resistance and damage mechanisms of rail steels subject to contact fatigue[J]. Wear, 2016, 364-365:130
[4] An L Q, Liu Y B, Liu D Y, et al. Effect of practical decarburized depth on fatigue property of 60Si2CrVAT spring steel[J]. J. Dalian Jiaotong Univ., 2009, 30(3):52(安丽乔,刘玉宝,刘德义等.脱碳深度对60Si2CrVAT弹簧钢疲劳性能的影响[J].大连交通大学学报, 2009, 30(3):52)
[5] Wang H J, Rong Z, Xiang L, et al. Effect of decarburization annealing temperature and time on the carbon content, microstructure, and texture of grain-oriented pure iron[J]. Int. J. Min. Met. Mater.,2017, 24:393
[6] Zhang C L, Liu Y Z, Zhou L Y, et al. Forming condition and control strategy of ferrite decarburization in 60Si2MnA spring steel wires for automotive suspensions[J]. Int. J. Min. Met. Mater., 2012, 19:116
[7] Hu L, Wang L, Ma H. Behaviors of oxidation and decarburization on surfaces of high carbon steel wire rods[J]. J. Iron Steel Res.,2016, 28(3):67(胡磊,王雷,麻晗.高碳钢盘条的表面氧化与脱碳行为[J].钢铁研究学报, 2016, 28(3):67)
[8] Chen Y L, Zuo M F, Luo Z L, et al. Theoretical and experimental study on surface decarburization of 60Si2Mn spring steel[J]. Trans.Mater. Heat Treat., 2015, 36:192(陈银莉,左茂方,罗兆良等. 60Si2Mn弹簧钢表面脱碳理论及试验研究[J].材料热处理学报, 2015, 36:192)
[9] Li H Y, Chen G, Tang W. Studies of ferrite decarburization behavior in spring steel for automotive suspensions[J]. Mater. Sci. Technol.,2014, 22(4):49(李红英,陈广,唐薇.汽车悬架用弹簧钢铁素体全脱碳行为研究[J].材料科学与工艺, 2014, 22(4):49)
[10] Xiao J F, Liu Y Z, Zhang C L, et al. Surface decarburization of spring steel 55SiCrA[J]. Heat Treat. Met., 2010, 35(12):94(肖金福,刘雅政,张朝磊等.弹簧钢55SiCrA脱碳规律的研究[J].金属热处理, 2010, 35(12):94)
[11] Masahiro N, Shigenobu N, Hiroshi Y, et al. Calculation of ferrite decarburizing depth based on steel chemical composition and heating conditions(FEATURE:Wire Rod and Bar Steels)[J]. R&D Kobe Steel Eng. Rep., 2006, 56(3):26(野村正裕,難波茂信,家口浩等.鋼の化学成分および加熱条件を考慮したフェライト脱炭深さの計算(特集:線材?棒鋼)[J]. R&D神戸製鋼技報, 2006, 56(3):26)
[12] Lu X Y, Wu C, Luo D X, et al. Behavioral research on decarburization and oxidation of the 55SiCr spring steel[J]. Heat Treat. Technol. Equip., 2016, 37(2):63(鲁修宇,吴超,罗德信等. 55SiCr弹簧钢脱碳与氧化行为研究[J].热处理技术与装备, 2016, 37(2):63)
[13] Liu L H, Ding W Z. Study on the decarburization of spring steel60Si2Mn[J]. Heat Treat., 2005, 20(3):6(刘丽华,丁伟中. 60Si2Mn弹簧钢脱碳的研究[J].热处理,2005, 20(3):6)
[14] Liu Y B, Zhang W, Tong Q, et al. Effects of temperature and oxygen concentration on the characteristics of decarburization of 55SiCr spring steel[J]. ISIJ Int., 2014, 54:1920
[15] Donahue S J, Renowden M. Automated atmosphere control system advances heat treating cycles[J]. Wire J. Int., 1997, 4:82
[16] Cai Q F. Furnace[M]. 3rd Ed., Beijing:Metallurgical Industry Press, 2007:135(蔡乔方.加热炉[M].第3版.北京:冶金工业出版社, 2007:135)
[17] Baud J, Ferrier A, Manenc J, et al. The oxidation and decarburizing of Fe-C alloys in air and the influence of relative humidity[J].Oxid. Met., 1975, 9:69
[18] Wang M. Study on surface decarbonization of steel 55SiCr used for suspension springs of automobile[D]. Beijing:University of Science and Technology Beijing, 2009(王猛.汽车弹簧用钢55SiCr的表面脱碳研究[D].北京:北京科技大学, 2009)
[19] Prawoto Y, Sato N, Otani I, et al. Carbon restoration for decarburized layer in spring steel[J]. J. Mater. Eng. Perform., 2004, 13:627
[20] Illingworth T C, Golosnoy I O. Numerical solutions of diffusioncontrolled moving boundary problems which conserve solute[J].J. Comput. Phys., 2005, 209:207
[21] Hu X J, Zhang B M, Chen S H, et al. Oxide scale growth on high carbon steel at high temperatures[J]. J. Iron Steel Res. Int., 2013,20:47
[22] Cao A R, Li Y F, Wang J, et al. Research of oxidation and decarburization behavior of spring steel 55SiCr[J]. Heat Treat. Met.,2010, 35(9):51(曹安然,李玉芳,王剑等.弹簧钢55SiCr氧化与脱碳特性的研究[J].金属热处理, 2010, 35(9):51)
[23] Manenc J, Vagnard G. Etude de L'oxydation D'alliages fer-carbone[J]. Corros. Sci., 1969, 9:857
[24] Plumensi J P, Kohn A, Vagnard G, et al. Etude de la solubilite du carbone dans le protoxyde de fer[J]. Corros. Sci., 1969, 9:309
[25] Setiawan A R, Bin Ani M H, Ueda M, et al. Oxygen permeability through internal oxidation zone in Fe-Cr alloys under dry and humid Conditions at 973 and 1073 K[J]. ISIJ Int., 2010, 50:259
[26] Shen J N, Zhou L J, Li T F. Effect of water vapor on high temperature oxidation of Fe-Cr alloys[J]. Chin. J. Mater. Res., 1998, 12:128(沈嘉年,周龙江,李铁藩.水蒸气加速Fe-Cr合金高温氧化的作用[J].材料研究学报, 1998, 12:128)
[27] Chen G. Effect of water vapor on high temperature oxidation behavior of Fe-13%Cr-5%Ni alloy at 800℃[D]. Beijing:Tsinghua University, 2012(陈刚.水蒸气对Fe-13%Cr-5%Ni合金在800℃高温氧化行为的影响[D].北京:清华大学, 2012)
[28] Luo H W, Xiang R, Chen L F, et al. Modeling decarburization kinetics of grain-oriented silicon steel[J]. Chin. Sci. Bull., 2014, 59:1778
[2] Choi S, van der Zwaag S. Prediction of decarburized ferrite depth of hypoeutectoid steel with simultaneous oxidation[J]. ISIJ Int., 2012,52:549
[3] Zhao X J, Guo J, Wang H Y, et al. Effects of decarburization on the wear resistance and damage mechanisms of rail steels subject to contact fatigue[J]. Wear, 2016, 364-365:130
[4] An L Q, Liu Y B, Liu D Y, et al. Effect of practical decarburized depth on fatigue property of 60Si2CrVAT spring steel[J]. J. Dalian Jiaotong Univ., 2009, 30(3):52(安丽乔,刘玉宝,刘德义等.脱碳深度对60Si2CrVAT弹簧钢疲劳性能的影响[J].大连交通大学学报, 2009, 30(3):52)
[5] Wang H J, Rong Z, Xiang L, et al. Effect of decarburization annealing temperature and time on the carbon content, microstructure, and texture of grain-oriented pure iron[J]. Int. J. Min. Met. Mater.,2017, 24:393
[6] Zhang C L, Liu Y Z, Zhou L Y, et al. Forming condition and control strategy of ferrite decarburization in 60Si2MnA spring steel wires for automotive suspensions[J]. Int. J. Min. Met. Mater., 2012, 19:116
[7] Hu L, Wang L, Ma H. Behaviors of oxidation and decarburization on surfaces of high carbon steel wire rods[J]. J. Iron Steel Res.,2016, 28(3):67(胡磊,王雷,麻晗.高碳钢盘条的表面氧化与脱碳行为[J].钢铁研究学报, 2016, 28(3):67)
[8] Chen Y L, Zuo M F, Luo Z L, et al. Theoretical and experimental study on surface decarburization of 60Si2Mn spring steel[J]. Trans.Mater. Heat Treat., 2015, 36:192(陈银莉,左茂方,罗兆良等. 60Si2Mn弹簧钢表面脱碳理论及试验研究[J].材料热处理学报, 2015, 36:192)
[9] Li H Y, Chen G, Tang W. Studies of ferrite decarburization behavior in spring steel for automotive suspensions[J]. Mater. Sci. Technol.,2014, 22(4):49(李红英,陈广,唐薇.汽车悬架用弹簧钢铁素体全脱碳行为研究[J].材料科学与工艺, 2014, 22(4):49)
[10] Xiao J F, Liu Y Z, Zhang C L, et al. Surface decarburization of spring steel 55SiCrA[J]. Heat Treat. Met., 2010, 35(12):94(肖金福,刘雅政,张朝磊等.弹簧钢55SiCrA脱碳规律的研究[J].金属热处理, 2010, 35(12):94)
[11] Masahiro N, Shigenobu N, Hiroshi Y, et al. Calculation of ferrite decarburizing depth based on steel chemical composition and heating conditions(FEATURE:Wire Rod and Bar Steels)[J]. R&D Kobe Steel Eng. Rep., 2006, 56(3):26(野村正裕,難波茂信,家口浩等.鋼の化学成分および加熱条件を考慮したフェライト脱炭深さの計算(特集:線材?棒鋼)[J]. R&D神戸製鋼技報, 2006, 56(3):26)
[12] Lu X Y, Wu C, Luo D X, et al. Behavioral research on decarburization and oxidation of the 55SiCr spring steel[J]. Heat Treat. Technol. Equip., 2016, 37(2):63(鲁修宇,吴超,罗德信等. 55SiCr弹簧钢脱碳与氧化行为研究[J].热处理技术与装备, 2016, 37(2):63)
[13] Liu L H, Ding W Z. Study on the decarburization of spring steel60Si2Mn[J]. Heat Treat., 2005, 20(3):6(刘丽华,丁伟中. 60Si2Mn弹簧钢脱碳的研究[J].热处理,2005, 20(3):6)
[14] Liu Y B, Zhang W, Tong Q, et al. Effects of temperature and oxygen concentration on the characteristics of decarburization of 55SiCr spring steel[J]. ISIJ Int., 2014, 54:1920
[15] Donahue S J, Renowden M. Automated atmosphere control system advances heat treating cycles[J]. Wire J. Int., 1997, 4:82
[16] Cai Q F. Furnace[M]. 3rd Ed., Beijing:Metallurgical Industry Press, 2007:135(蔡乔方.加热炉[M].第3版.北京:冶金工业出版社, 2007:135)
[17] Baud J, Ferrier A, Manenc J, et al. The oxidation and decarburizing of Fe-C alloys in air and the influence of relative humidity[J].Oxid. Met., 1975, 9:69
[18] Wang M. Study on surface decarbonization of steel 55SiCr used for suspension springs of automobile[D]. Beijing:University of Science and Technology Beijing, 2009(王猛.汽车弹簧用钢55SiCr的表面脱碳研究[D].北京:北京科技大学, 2009)
[19] Prawoto Y, Sato N, Otani I, et al. Carbon restoration for decarburized layer in spring steel[J]. J. Mater. Eng. Perform., 2004, 13:627
[20] Illingworth T C, Golosnoy I O. Numerical solutions of diffusioncontrolled moving boundary problems which conserve solute[J].J. Comput. Phys., 2005, 209:207
[21] Hu X J, Zhang B M, Chen S H, et al. Oxide scale growth on high carbon steel at high temperatures[J]. J. Iron Steel Res. Int., 2013,20:47
[22] Cao A R, Li Y F, Wang J, et al. Research of oxidation and decarburization behavior of spring steel 55SiCr[J]. Heat Treat. Met.,2010, 35(9):51(曹安然,李玉芳,王剑等.弹簧钢55SiCr氧化与脱碳特性的研究[J].金属热处理, 2010, 35(9):51)
[23] Manenc J, Vagnard G. Etude de L'oxydation D'alliages fer-carbone[J]. Corros. Sci., 1969, 9:857
[24] Plumensi J P, Kohn A, Vagnard G, et al. Etude de la solubilite du carbone dans le protoxyde de fer[J]. Corros. Sci., 1969, 9:309
[25] Setiawan A R, Bin Ani M H, Ueda M, et al. Oxygen permeability through internal oxidation zone in Fe-Cr alloys under dry and humid Conditions at 973 and 1073 K[J]. ISIJ Int., 2010, 50:259
[26] Shen J N, Zhou L J, Li T F. Effect of water vapor on high temperature oxidation of Fe-Cr alloys[J]. Chin. J. Mater. Res., 1998, 12:128(沈嘉年,周龙江,李铁藩.水蒸气加速Fe-Cr合金高温氧化的作用[J].材料研究学报, 1998, 12:128)
[27] Chen G. Effect of water vapor on high temperature oxidation behavior of Fe-13%Cr-5%Ni alloy at 800℃[D]. Beijing:Tsinghua University, 2012(陈刚.水蒸气对Fe-13%Cr-5%Ni合金在800℃高温氧化行为的影响[D].北京:清华大学, 2012)
[28] Luo H W, Xiang R, Chen L F, et al. Modeling decarburization kinetics of grain-oriented silicon steel[J]. Chin. Sci. Bull., 2014, 59:1778