基于组织和结构调控9CrV钢大尺寸活塞性能的优化  

Properties Optimization of 9CrV Steel for Large Piston Based on Microstructure and Structure Control

作　　者：王磊[1] 张博 张宝燕 刘杨[1] 宋秀[1] 李永胜 WANG Lei;ZHANG Bo;ZHANG Baoyan;LIU Yang;SONG Xiu;LI Yongsheng(Key Laboratory for Anisotropy and Texture of Materials,Northeastern University,Shenyang 110819,China;Shandong Tianrui Heavy Industry Co.Ltd.,Weifang 261061,China)

机构地区：[1]东北大学材料各向异性与织构教育部重点实验室,沈阳110819 [2]山东天瑞重工有限公司,潍坊261061

出　　处：《材料研究学报》2023年第11期827-836,共10页Chinese Journal of Materials Research

基　　金：国家自然科学基金(U1708253);泰山产业领军人才计划项目(tscy20170318)。

摘　　要：研究了热处理和结构调控对直径为190 mm的9CrV钢仿形活塞不同部位显微组织和力学性能的影响及其机理。结果表明,经850℃×5 h-230℃×4 h等温淬火、230℃×4 h回火后,9CrV钢活塞的表层至心部依次为下贝氏体、贝氏体+索氏体+M/A岛、珠光体类组织;表层的抗拉强度和冲击吸收功均高于心部。淬火温度降至800℃、回火温度升至400℃,使表层的抗拉强度提高到1610 MPa、冲击吸收功降低到7.4 J,心部的冲击韧性有所提高但是强度降低。经800℃×5 h-230℃×4 h等温淬火、230℃×4 h+400℃×4 h二次回火后,表层的抗拉强度达到1672 MPa、冲击吸收功达到9.8 J,且改善了心部的冲击韧性,使活塞整体的强度与韧性趋于平衡。淬火加热温度的降低保留了适量的未溶碳化物颗粒,阻碍了奥氏体的长大和细化了晶粒,从而提高了钢的强度。在230℃回火使残余奥氏体转化为下贝氏体、防止在400℃回火(提高心部韧性)时生成薄壳碳化物和平衡了整体韧性。综合热处理和活塞结构的调控,实现了大尺寸活塞的整体强韧性平衡。In order to solve the imbalance between strength and toughness in different cross sections of a large size piston for hydraulic crushing hammer,the influence of heat treatment and microstructural adjustmen/control on the microstructure and mechanical properties of 9CrV steel near-real shaped piston with a diameter of 190 mm was studied.The results show that when the piston were austenitized at 850℃for 5 h and quenched at 230℃for 4 h,then tempered at 230℃for 4 h,the microstructure of a piston consists of bainite,bainite+troostite+residual austenite and pearlite respectively,from the surface to the core.The tensile strength of the piston surface layer is 1442 MPa,the impact absorbed energy is 11 J,the impact toughness in the piston core part is poor,and the impact toughness is the lowest at 2/3 R of the piston.When the austenitizing temperature is decreased to 800℃and tempering tempera-ture is increased to 400℃,the tensile strength of the piston surface layer increased to 1610 MPa,and the impact absorbed energy decreased to 7.4 J.The impact toughness of the piston core shows an increasing tendency,while the strength will decrease.When the piston is austenitized at 800℃for 5 h and followed by quenching at 230℃for 4 h,then tempering first at 230℃for 4 h and then at 400℃for 4 h,the tensile strength of the piston surface layer becomes 1672 MPa,the impact absorbed energy becomes 9.8 J.The impact toughness of piston core part has been improved,and the combination of strength and toughness of the piston tend to balance.It is found that with the lower austenitizing temperature a large number of undissolved carbide particles will be retained,it will hinder austenite growing,but refine grains.With the increasing tempering temperature,the dislocation tangles to pearlite ferrite will be restored,and the toughness of piston core can be improved.The carbon-rich residual austenite film in the bainite of piston surface layer is stable.When it is tempered at 400℃,the carbide thin film will precipitate during the

关 键 词：金属材料 9CrV钢 大尺寸仿形活塞 力学性能 二次回火 

分 类 号：TG142.3[一般工业技术—材料科学与工程]