回火对微合金管线钢疲劳裂纹扩展行为的影响  

Effects of tempering treatment on fatigue crack propagation behavior of microalloyed pipeline steels

作　　者：李红英[1] 宾杰[1] 林武[1] 魏冬冬[1] 李阳华[1] 曹俊[1] 

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2011年第9期2635-2641,共7页Journal of Central South University:Science and Technology

基　　金：湖南省自然科学基金资助项目(05JJ30200)

摘　　要：采用MTS858电液伺服万能试验机、扫描电镜及透射电镜研究回火对一种高强度微合金管线钢疲劳裂纹扩展行为的影响。研究结果表明:回火可提高微合金管线钢疲劳裂纹扩展的门槛值,降低疲劳裂纹扩展速率,但对裂纹扩展稳态区的扩展速率影响不大;回火使碳氮化物沉淀析出、晶间马氏体/奥氏体(M/A)组元由岛状转变为点状及细条状,形成马氏体薄膜结构,阻碍变形和裂纹在材料中扩展,增加裂纹的偏折程度;在控轧控冷终冷温度进行2～4 h回火热处理,可以提高微合金管线钢强韧性和抗疲劳裂纹扩展能力。The effects of different tempering treatments on fatigue crack propagation behavior of a high strength microalloyed pipeline steel were investigated by MTS858 material testing system,scanning electron microscopy and transmission electron microscopy.The results show that tempering treatments can improve the fatigue crack propagation threshold and reduce the fatigue crack growth rate of microalloyed pipeline steels,but with little effects on the intermediate region of stable crack propagation.Tempering treatment can promote the precipitation of microalloyed carbonitrides and transform the martensite/austenite（M/A） components at the grain boundary from islands to spots and strips,and the M/A components can be further changed to thin-film martensite as tempering time increases,and all these structures can inhibit the propagation and increase the deflection of fatigue crack.The strength,toughness and fatigue crack propagation resistance of microalloyed pipeline steels can be promoted by 2？4 h tempering at the final cooling temperature of thermo-mechanical control process.

关 键 词：回火 微合金管线钢 针状铁素体 疲劳 裂纹扩展行为 

分 类 号：TG142.1[一般工业技术—材料科学与工程]