316LN不锈钢锻造裂纹分析及工艺控制
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摘要
316LN奥氏体不锈钢作为核电主管道用钢的关键材料,具有良好的耐晶间腐蚀性能和力学性能。针对316LN在锻造过程中开裂的现象,本文研究路线从原始铸锭→锻态钢锭→锻造工艺参数,分析316LN锻造开裂的原因。在借助于金相显微镜、SEM、能谱仪分析铸态、锻态组织特征基础之上,通过Gleeble—1500D进行高温拉伸实验,研究316LN的高温塑性以及锻造开裂过程中裂纹萌生机制,为大型锻件的工艺设计和分析提供参考。
原始铸锭由于存在着严重的成分偏析、区域偏析现象,因此在锻前必须进行热处理,锻前热处理工艺对后续锻造成型质量保证起着重要的作用。
对实际生产过程中锻造开裂的钢锭进行了常温组织分析,钢锭中非金属夹杂主要以脆性氧化铝类夹杂物为主,平均级别2.0级,加大了钢锭在高温锻造过程中开裂的倾向。
借助于高温拉伸实验研究了高温拉伸过程中裂纹的萌生及扩展规律,裂纹的萌生主要通过空洞在晶界上形核、长大、积聚来完成。细观损伤力学在预测材料破坏的过程中可以起到很好的作用。
通过高温拉断实验研究316LN在高温塑性,1050℃～1250℃在应变速率为0.5S-1时,材料有很好的塑性;断口分析以及断口附近的组织分析表明,高温断裂主要是沿晶断裂;空洞的萌生主要在晶界上,尤其在三叉晶界的交汇处;拉伸过程中再结晶的发生可以有效阻止裂纹的扩展。
为了验证316LN在1050℃～1250℃热变形的可行性,进行了缩比工艺实验,通过宏观以及微观分析,试样都没有微裂纹萌生。
316LN austenitic stainless steel, as the key materials for the steel pipe in the nuclear power, shows good resistance to intergranular stress corrosion and mechanical. According to the problems that 316LN austenitic stainless steel is easy to crack in forging, this thesis focuses on the causes of 316LN forging cracks with the route from original cast ingot to forging state ingot, and then to forging technology. Based on the analysis of the features of as-cast structure and forging state organization with the help of metallographic microscope, SEM(scanning electron microscope) and ESD(energy disperse spectroscopy), a research has been performed with Gleeble-1500D on the pyroplasticity of 316LN and the mechanism of crack initiation during the forging, which provides references for the process design and analysis of heavy forgings.
For the serious segregation in composition and region, the original cast ingot must be through the heat treatment before forging which plays an important role in the quality guarantee of forgings.
Having performed the organization analysis in normal temperature to the ingot with cracks formed in the practical manufacturing process, we find, the nonmetallic inclusions in the ingot are mainly brittle aluminum oxide with an average level 2.0, increasing the cracking tendency in the hot forging.
Micro-crack initiation is principally accomplished by the nucleation, growth, and coalescence of voids on the grain boundary, with the research of crack initiation and propagation rule in the high tensile by the high tensile experiment. And microscopic damage mechanics is good for forecasting the failure process of materials.
The high tensile experiment concerned on the pyroplasticity of 316LN proves that this kind of material has excellent pyroplasticity in 1050℃~1250℃and with the strain rate 0.5s-1. Besides, fracture analysis and fractography show that high-temperature fracture, mainly intergranular fracture. Voids form mainly on the grain boundaries, especially the interchange of grain boundaries. Recrystallization in the drawing process can prevent the extension of cracks effectively.
To check the feasibility of hot deformation of 316LN in 1050℃~1250℃, scaled process experiments have been performed. Through the macro-analysis and micro-analysis, samples have no micro-crack initiation.
原始铸锭由于存在着严重的成分偏析、区域偏析现象,因此在锻前必须进行热处理,锻前热处理工艺对后续锻造成型质量保证起着重要的作用。
对实际生产过程中锻造开裂的钢锭进行了常温组织分析,钢锭中非金属夹杂主要以脆性氧化铝类夹杂物为主,平均级别2.0级,加大了钢锭在高温锻造过程中开裂的倾向。
借助于高温拉伸实验研究了高温拉伸过程中裂纹的萌生及扩展规律,裂纹的萌生主要通过空洞在晶界上形核、长大、积聚来完成。细观损伤力学在预测材料破坏的过程中可以起到很好的作用。
通过高温拉断实验研究316LN在高温塑性,1050℃～1250℃在应变速率为0.5S-1时,材料有很好的塑性;断口分析以及断口附近的组织分析表明,高温断裂主要是沿晶断裂;空洞的萌生主要在晶界上,尤其在三叉晶界的交汇处;拉伸过程中再结晶的发生可以有效阻止裂纹的扩展。
为了验证316LN在1050℃～1250℃热变形的可行性,进行了缩比工艺实验,通过宏观以及微观分析,试样都没有微裂纹萌生。
316LN austenitic stainless steel, as the key materials for the steel pipe in the nuclear power, shows good resistance to intergranular stress corrosion and mechanical. According to the problems that 316LN austenitic stainless steel is easy to crack in forging, this thesis focuses on the causes of 316LN forging cracks with the route from original cast ingot to forging state ingot, and then to forging technology. Based on the analysis of the features of as-cast structure and forging state organization with the help of metallographic microscope, SEM(scanning electron microscope) and ESD(energy disperse spectroscopy), a research has been performed with Gleeble-1500D on the pyroplasticity of 316LN and the mechanism of crack initiation during the forging, which provides references for the process design and analysis of heavy forgings.
For the serious segregation in composition and region, the original cast ingot must be through the heat treatment before forging which plays an important role in the quality guarantee of forgings.
Having performed the organization analysis in normal temperature to the ingot with cracks formed in the practical manufacturing process, we find, the nonmetallic inclusions in the ingot are mainly brittle aluminum oxide with an average level 2.0, increasing the cracking tendency in the hot forging.
Micro-crack initiation is principally accomplished by the nucleation, growth, and coalescence of voids on the grain boundary, with the research of crack initiation and propagation rule in the high tensile by the high tensile experiment. And microscopic damage mechanics is good for forecasting the failure process of materials.
The high tensile experiment concerned on the pyroplasticity of 316LN proves that this kind of material has excellent pyroplasticity in 1050℃~1250℃and with the strain rate 0.5s-1. Besides, fracture analysis and fractography show that high-temperature fracture, mainly intergranular fracture. Voids form mainly on the grain boundaries, especially the interchange of grain boundaries. Recrystallization in the drawing process can prevent the extension of cracks effectively.
To check the feasibility of hot deformation of 316LN in 1050℃~1250℃, scaled process experiments have been performed. Through the macro-analysis and micro-analysis, samples have no micro-crack initiation.
引文
[1]李红英,刘建章.世界核电站的现状与展望[J].中国钼业, 1997(4): 56-61
[2]宋树康,刘志颍,郑建能,等.第三代AP1000核电主管道的研制[J].大型铸锻件, 2011(1): 1-4
[3]张效迅.大锻件锻造成形过程中内部空洞型缺陷演化规律的研究[D].上海:上海交通大学, 2009
[4]孙红,佟莹等.锻造技术的发展历程及未来趋势[J].科技创新导报, 2009(12): 161-162
[5]常红英. 1Cr13钢锻造开裂原因探讨[J].上海钢研, 1994(6): 21-241
[6]姚铁光. 05钢钢锭锻造开裂原因分析[J].大型铸锻件, 2001 (4): 11-14
[7]崇鹏. 20CrMnTi锻造开裂原因分析[J].鄂钢科技, 2010(4): 12-13
[8]舒金波. 35CrMo钢钻头锻造开裂原因分析[J].金属热处理, 2004(29): 8
[9]莫立华. XM—19不锈钢锻造开裂的研究[J].理化检验, 1999(1): 1
[10]常红英.一炉含Se4J38锻造开裂的原因分析[J].上海钢研, 1994(6): 32-33
[11]韩静涛.有效控制夹杂性裂纹的大型锻件锻造及处理方法[J].塑性工程学报, 1996(3): 20-25
[12]金宏伟. 34crNi3Mo钢锭锻裂原因[J] .物理测试, 2001(3): 40-44
[13] D. A. Melford,Phil, Trans, R.Soc,London A, 1980, 29S(1430): 89
[14]何文武.锻造裂纹的分析与防治[J].锻压技术, 2010(2): 16-17
[15]温彤,廖林灿,张湘伟.金属剪切过程的理论研究状况[J].锻压技术, 2000, 25(3): 44-57
[16] Freudenthal A M. The Nelastic Behavior of Solids [M]. New York: Wiley, 1950
[17] Gillemat L, Czoboly E. Genetalized theory of f racture [ A ] . Proc.Symp.Fracture [C] . Marianskela zne: Springer, 1970
[18]黄志超,占金青,陈伟.基于Ayada损伤模型的板料冲载过程数值模拟[J].机械设计与制造, 2007(10): 49-51
[19] McClintock F A. A criterion for ductile fracture by the growth of hole[J] Appl, Mech, 1968, 35: 363-371.
[20] Cockcroft M G, Latham D J. On the ductile enlargment of voidsin triaxial stress fields[ J ] . J. Int. Metals, 1968, 96(3): 384.
[21] Fang Gang , Lei Liping, Zeng Pan. Criteria of metal ductile fracture and numerical simulation for m etal forging[ J] . Chin J M ech Eng, 2002, 38(supp): 21-25.
[22]陈实,周贤宾.成形极限预测韧性断裂准则及屈服准则的影响[J].北京航空航天大学学报, 2006, 32: 969-973
[23] Bao Yingbin, Wierzbichi T. A comparative study on various ductile crack formation crit eria [J] . J E ng Mater Technol, 2004, 126: 314-324.
[24] Clift S E, Hart ley P, Sturgess C E N, etal. Fracture prediction in plastic deformation process [J] . I nt J Mech Sci,1990, 32: 1-17.
[25]张莉,李升军. DEFORM在金属塑性成型中的应用[M].北京:机械工业出版社.
[26]刘建生,刘志颖,陈慧琴,陈金科.模拟技术的集成及在大型锻造工艺研发中的应用[J].大型铸锻件, 2009(1) : 2-5.
[27]陆世英,张延凯,康喜范等.不锈钢[M] .北京:原子能出版社, 1988.
[28]陆世英,张延凯,康喜范等.高氮钢和不锈钢-生产、性能与应用[M].北京:化学工业出版社, 2006.
[29] Lula,R.A.,Manganese Stainless steels,The Manganese Centre,France, 1986, 29-31.
[30] Leslie, W. C. The Physical Metallurgy of steels, McGraw Hill Internl.Book Co. Intnl.Students Edn., London, 355, 1982, 355
[31] Pickering, F.B, Proc.of Intnl.Conf.on High Nitrogen Steels HNS-88, 1989, 17
[32] Stein,G.,Menzel, J.and Dorr, H.Proc.of Intnl.Conf. On High Nitrogen Steels HNS-88, 1989, 32
[33]赵彦芬,遆文新,汪小龙,薛飞.核电站用钢管材料及其国产化[J].钢管2007, 36(2): 11-14
[34] T.S. Byun , N. Hashimoto, K. Farrell. Temperature dependence of strain hardening and plastic instability behaviors in austenitic stainless steels[J]. Acta Materialia, 2004, 52: 3889–3899
[35] Songtao Wang, Ke Yang, Yiyin Shan, Laifeng Li. Plastic deformation and fracture behaviors of nitrogen-alloyed austenitic stainless steels[J]. Materials Science and Engineering: A. 2008, 490: 95–104
[36]陈书贵编译.316L和316LN奥氏体不锈钢的低温疲劳性能[J].大型铸锻件, 1993(4): 72-75
[37]张志文,高新,白学周等.锻造工艺学[M].北京:机械工业出版社出,1983: 29-30
[38]甘志强.不锈钢夹杂物的成因及降低其含量的途径[J].江西冶金, 1998(2), 9
[39] E .T .Turkdogan, JISI, 1995. V180, P349
[40] D. A. Melford, Phil, Trans, R. Soc,London A, 1980, 29S(1413): 89
[41]越谷哲郎.关于锻造加热的想法和问题点[J],日本铸锻造与热处理, 1990(5): 13
[42]任猛等,热送钢锭自降温缓冷新工艺[J].大型铸锻件, 1992(2): 12
[43] J.R.Wilcox and R.W.K.Honeycomebe. (proc.Conf), July.1980, 108
[44]任猛,李保华,钢锭开裂的机理及防治方法[J].大型铸锻件, 1992(3): 39-41
[45]上海机械制造工艺研究所.金相分析技术,上海:科学技术文献出版社, 1987, 11(85)
[46]荣伟,张德驺,马茂元,等.金属断裂韧性与微观参量的关系[J].哈尔滨船舶工程学院学报, 1994(6): 31
[47]汪大年.金属塑性成形原理[M] .北京:机械工业出版社, 1986
[48]丁建波.低碳钢拉伸试样端口分析[J].九江职业技术学院学报, 2003 (4):18-20
[49]马若涓,郑长卿,郑秀芳.金属材料空穴型损伤表征参数的探讨[J].钢铁研究, 1988(8): 63
[50]刘先兰,张文玉,刘楚明.细观损伤力学及其在金属塑性加工中的作用[J].锻压技术, 2008(2): 33
[51]束德林.金属力学性能[M].北京:机械工业出版社, 2002: 24
[52]司马爱平.应力三维度对材料断裂破坏的影响[D]:上海:上海交通大学, 2009
[53]汪大年.金属塑性成型原理[M].北京:机械工业出版社, 1986: 48
[54]钟群鹏,赵子华.断口学[M].北京:高等教育出版社, 1986: 48
[55]陈森灿,叶庆荣.金属塑性加工原理[M].北京:清华大学出版社, 1991: 87
[56]任猛,李保华.钢锭开裂的机理及防治方法[J].大型铸锻件, 1992(3): 57
[2]宋树康,刘志颍,郑建能,等.第三代AP1000核电主管道的研制[J].大型铸锻件, 2011(1): 1-4
[3]张效迅.大锻件锻造成形过程中内部空洞型缺陷演化规律的研究[D].上海:上海交通大学, 2009
[4]孙红,佟莹等.锻造技术的发展历程及未来趋势[J].科技创新导报, 2009(12): 161-162
[5]常红英. 1Cr13钢锻造开裂原因探讨[J].上海钢研, 1994(6): 21-241
[6]姚铁光. 05钢钢锭锻造开裂原因分析[J].大型铸锻件, 2001 (4): 11-14
[7]崇鹏. 20CrMnTi锻造开裂原因分析[J].鄂钢科技, 2010(4): 12-13
[8]舒金波. 35CrMo钢钻头锻造开裂原因分析[J].金属热处理, 2004(29): 8
[9]莫立华. XM—19不锈钢锻造开裂的研究[J].理化检验, 1999(1): 1
[10]常红英.一炉含Se4J38锻造开裂的原因分析[J].上海钢研, 1994(6): 32-33
[11]韩静涛.有效控制夹杂性裂纹的大型锻件锻造及处理方法[J].塑性工程学报, 1996(3): 20-25
[12]金宏伟. 34crNi3Mo钢锭锻裂原因[J] .物理测试, 2001(3): 40-44
[13] D. A. Melford,Phil, Trans, R.Soc,London A, 1980, 29S(1430): 89
[14]何文武.锻造裂纹的分析与防治[J].锻压技术, 2010(2): 16-17
[15]温彤,廖林灿,张湘伟.金属剪切过程的理论研究状况[J].锻压技术, 2000, 25(3): 44-57
[16] Freudenthal A M. The Nelastic Behavior of Solids [M]. New York: Wiley, 1950
[17] Gillemat L, Czoboly E. Genetalized theory of f racture [ A ] . Proc.Symp.Fracture [C] . Marianskela zne: Springer, 1970
[18]黄志超,占金青,陈伟.基于Ayada损伤模型的板料冲载过程数值模拟[J].机械设计与制造, 2007(10): 49-51
[19] McClintock F A. A criterion for ductile fracture by the growth of hole[J] Appl, Mech, 1968, 35: 363-371.
[20] Cockcroft M G, Latham D J. On the ductile enlargment of voidsin triaxial stress fields[ J ] . J. Int. Metals, 1968, 96(3): 384.
[21] Fang Gang , Lei Liping, Zeng Pan. Criteria of metal ductile fracture and numerical simulation for m etal forging[ J] . Chin J M ech Eng, 2002, 38(supp): 21-25.
[22]陈实,周贤宾.成形极限预测韧性断裂准则及屈服准则的影响[J].北京航空航天大学学报, 2006, 32: 969-973
[23] Bao Yingbin, Wierzbichi T. A comparative study on various ductile crack formation crit eria [J] . J E ng Mater Technol, 2004, 126: 314-324.
[24] Clift S E, Hart ley P, Sturgess C E N, etal. Fracture prediction in plastic deformation process [J] . I nt J Mech Sci,1990, 32: 1-17.
[25]张莉,李升军. DEFORM在金属塑性成型中的应用[M].北京:机械工业出版社.
[26]刘建生,刘志颖,陈慧琴,陈金科.模拟技术的集成及在大型锻造工艺研发中的应用[J].大型铸锻件, 2009(1) : 2-5.
[27]陆世英,张延凯,康喜范等.不锈钢[M] .北京:原子能出版社, 1988.
[28]陆世英,张延凯,康喜范等.高氮钢和不锈钢-生产、性能与应用[M].北京:化学工业出版社, 2006.
[29] Lula,R.A.,Manganese Stainless steels,The Manganese Centre,France, 1986, 29-31.
[30] Leslie, W. C. The Physical Metallurgy of steels, McGraw Hill Internl.Book Co. Intnl.Students Edn., London, 355, 1982, 355
[31] Pickering, F.B, Proc.of Intnl.Conf.on High Nitrogen Steels HNS-88, 1989, 17
[32] Stein,G.,Menzel, J.and Dorr, H.Proc.of Intnl.Conf. On High Nitrogen Steels HNS-88, 1989, 32
[33]赵彦芬,遆文新,汪小龙,薛飞.核电站用钢管材料及其国产化[J].钢管2007, 36(2): 11-14
[34] T.S. Byun , N. Hashimoto, K. Farrell. Temperature dependence of strain hardening and plastic instability behaviors in austenitic stainless steels[J]. Acta Materialia, 2004, 52: 3889–3899
[35] Songtao Wang, Ke Yang, Yiyin Shan, Laifeng Li. Plastic deformation and fracture behaviors of nitrogen-alloyed austenitic stainless steels[J]. Materials Science and Engineering: A. 2008, 490: 95–104
[36]陈书贵编译.316L和316LN奥氏体不锈钢的低温疲劳性能[J].大型铸锻件, 1993(4): 72-75
[37]张志文,高新,白学周等.锻造工艺学[M].北京:机械工业出版社出,1983: 29-30
[38]甘志强.不锈钢夹杂物的成因及降低其含量的途径[J].江西冶金, 1998(2), 9
[39] E .T .Turkdogan, JISI, 1995. V180, P349
[40] D. A. Melford, Phil, Trans, R. Soc,London A, 1980, 29S(1413): 89
[41]越谷哲郎.关于锻造加热的想法和问题点[J],日本铸锻造与热处理, 1990(5): 13
[42]任猛等,热送钢锭自降温缓冷新工艺[J].大型铸锻件, 1992(2): 12
[43] J.R.Wilcox and R.W.K.Honeycomebe. (proc.Conf), July.1980, 108
[44]任猛,李保华,钢锭开裂的机理及防治方法[J].大型铸锻件, 1992(3): 39-41
[45]上海机械制造工艺研究所.金相分析技术,上海:科学技术文献出版社, 1987, 11(85)
[46]荣伟,张德驺,马茂元,等.金属断裂韧性与微观参量的关系[J].哈尔滨船舶工程学院学报, 1994(6): 31
[47]汪大年.金属塑性成形原理[M] .北京:机械工业出版社, 1986
[48]丁建波.低碳钢拉伸试样端口分析[J].九江职业技术学院学报, 2003 (4):18-20
[49]马若涓,郑长卿,郑秀芳.金属材料空穴型损伤表征参数的探讨[J].钢铁研究, 1988(8): 63
[50]刘先兰,张文玉,刘楚明.细观损伤力学及其在金属塑性加工中的作用[J].锻压技术, 2008(2): 33
[51]束德林.金属力学性能[M].北京:机械工业出版社, 2002: 24
[52]司马爱平.应力三维度对材料断裂破坏的影响[D]:上海:上海交通大学, 2009
[53]汪大年.金属塑性成型原理[M].北京:机械工业出版社, 1986: 48
[54]钟群鹏,赵子华.断口学[M].北京:高等教育出版社, 1986: 48
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