P92耐热钢接头组织与冲击性能
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摘要
P92铁素体耐热钢因其优异的高温综合性能而作为超超临界发电机组用钢.采用金相显微镜﹑显微硬度计和扫描电子显微镜等分析方法,研究了TIG自熔焊后760℃回火不同保温时间对P92钢接头组织、显微硬度及冲击性能的影响,从显微组织和断口形貌角度对性能的变化进行了分析.结果表明:P92钢焊态下焊缝区平均显微硬度为400HV_(0.5),冲击韧性值为20J.经回火热处理,焊缝区显微硬度显著降低,冲击韧性提高,接头中δ-铁素体体积分数显著减少.在760℃回火保温7h后,焊缝区平均硬度下降到234HV_(0.5),冲击韧性值增加到86J.随回火时间的延长,断口形貌从韧/脆混合断裂向韧性断裂过渡.
P92ferrite heat-resistant steel has been taken as raw stuff for ultra-supercritical(USC)powergenerating set because of its excellent high-temperature performance.The effect of heat-proof time after TIG self-fluxing welding of P92 steel joint with tempering at 760 ℃ on its microstructure,microhardness and anti-impact performance was investigated by using relevant analysis method such as metallographic microscope,scanning electron microscope,and microhardness tester.The performance change was analyzed according to the microstructure and fracture morphology.The result showed that the average microhardness of P92 steel weld zone in a welding state would be 400HV_(0.5)and impact toughness would be 20 J.After tempering treatment,the microhardness of weld zone would reduce significantly,impact toughness would increase,and the content ofδ-ferrite within the joint would reduce significantly.The average microhardness of weld zone would be decreased to 234HV_(0.5)and impact toughness would be increased to 86 Jafter tempering at 760℃for 7h.With extending the heat-proof time of tempering,the fracture morphology would transform from ductile/brittle mixed fracture into ductile fracture.
P92ferrite heat-resistant steel has been taken as raw stuff for ultra-supercritical(USC)powergenerating set because of its excellent high-temperature performance.The effect of heat-proof time after TIG self-fluxing welding of P92 steel joint with tempering at 760 ℃ on its microstructure,microhardness and anti-impact performance was investigated by using relevant analysis method such as metallographic microscope,scanning electron microscope,and microhardness tester.The performance change was analyzed according to the microstructure and fracture morphology.The result showed that the average microhardness of P92 steel weld zone in a welding state would be 400HV_(0.5)and impact toughness would be 20 J.After tempering treatment,the microhardness of weld zone would reduce significantly,impact toughness would increase,and the content ofδ-ferrite within the joint would reduce significantly.The average microhardness of weld zone would be decreased to 234HV_(0.5)and impact toughness would be increased to 86 Jafter tempering at 760℃for 7h.With extending the heat-proof time of tempering,the fracture morphology would transform from ductile/brittle mixed fracture into ductile fracture.
引文
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[2]LUCON E.A closer look at the fracture toughness of ferritic/martensitic steels[J].Journal of Nuclear Materials,2007,367-370(4):575-580.
[3]沈琦,刘鸿国.新型耐热钢T/P92、T/P122在超超临界机组中的应用及监督[J].电力建设,2010,31(10):71-75.
[4]樊丁,周璟,季根顺,等.409L铁素体不锈钢的热变形行为[J].兰州理工大学学报,2010,36(1):12-15.
[5]SAWADA K,KUSHIMA H,KIMURA K,et al.Z-phase formation and its effect on long-term creep strength in 9%-12%Cr creep resistant steels[J].Transactions of the Indian Institute of Metals,2010,63(2):117-122.
[6]HOLLNER S,FOUMIER B,PENDU J L,et al.High-temperature mechanical properties improvement on modified 9Cr-1Mo martensitic steel through thermomechanical treatments[J].Journal of Nuclear Materials,2010,405(2):101-108.
[7]杨建平,郭军,乔亚霞,等.超超临界机组用P92钢焊接技术的研究[J].中国电机工程学报,2007,27(23):55-60.
[8]MOHYLA P,FOLDYNOVK.Effect of post-welding heat treatment on mechanical properties of joints of steel P92formed by submerged arc welding[J].Metal Science and Heat Treatment,2014,56(3):206-209.
[9]MADURAIMUTHU V,VASUDEVAN M,PARAMES-WARAN P.Studies on improvement of toughness in modified 9Cr-1Mo steel A-TIG weld joint[J].Transactions Indian Institute of Metals,2015,68(2):181-189.
[10]周强国,石全强,严伟,等.正火温度对含硅型高铬马氏体耐热钢性能的影响[J].材料研究学报,2013,27(5):461-468.
[11]许林青.T92铁素体钢相变行为及热处理工艺的研究[D].天津:天津大学,2013.