【摘要】 通过蠕变曲线测定及组织形貌观察,研究了403Nb钢的蠕变性能特点、变形特征、组织及其变化规律。结果表明:403Nb钢具有明显的温度敏感性,在试验条件下,403Nb钢蠕变激活能为463 kJ/mol,组织为回火板条马氏体,相邻马氏体板条组间取向几乎垂直。在马氏体中存在高密度的位错和尺寸约0.2μm的残留NbC,在马氏体板条界,特别是晶界处沉淀大量更为细小的纳米Cr23C6。蠕变期间,NbC十分稳定,但晶界处(Cr,Fe)23C6部分向(Cr,Fe)7C3转变。403Nb钢的蠕变变形机制是晶界滑移、位错滑移及由位错增值束集引起的动态再结晶,对上述过程碳化物起到阻碍作用,提高了钢的蠕变抗力。更多还原

【Abstract】 Creep performance,deformation mechanism,and evolution of microstructure of 403Nb steel were investigated by means of optical microscope,SEM,TEM and creep tests.Results show that the 403Nb steel is sensitive to temperature,creep activation energy of the steel under 260 MPa at 580-620 ℃ is measured to be 463 kJ/mol.The microstructure of the steel consists of tempered lath martensite,in which the orientation of the adjacent lath martensite bundles is perpendicular each other.High density dislocations and residual particle-like NbC carbides about 0.2μm in size are observed in the martensite laths,and fine Cr23C6 carbide particles are precipitated along the boundaries of martensite laths and grains.During creep,the NbC particles in the steel is stable,but some of(Cr,Fe)23C6 particles at boundaries are transformed into(Cr,Fe)7C3 phase.The creep deformation mechanism of the steel is migrating of grain boundary,dislocation sliding and dynamic recrystallization caused by the multiplication of dislocations.The particle-like carbides in the steel possess obvious effects of hindering the boundary migration and dislocation movement to improve the creep resistance of 403Nb steel.更多还原