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为扩大403Nb耐热钢的使用范围,比较研究了热连轧及热处理态403Nb钢的组织及蠕变性能。结果表明:403Nb钢在高温轧制时发生了动态回复及动态再结晶,组成相包括:α-Fe、Cr23C6及少量的NbC。其中,碳化物颗粒粗大,分布不均。经1050℃淬火后,获得了板条马氏体及残留的NbC。随着淬火温度的提高,晶粒有所长大,当温度达到1150℃时,出现较多沿晶界分布的δ铁素体。采用优化的热处理工艺,即1100℃淬火、650℃回火时,在原马氏体板条内及板条间弥散析出大量纳米级以Cr23C6为主的碳化物,此时,钢的使用温度及蠕变寿命可大幅度提高。文中阐述了钢组织的形成机制。
In order to expand the use range of 403Nb heat-resistant steel, the microstructure and creep properties of hot-rolled 403Nb steel and heat-treated 403Nb steel were comparatively studied. The results show that the dynamic recrystallization and dynamic recrystallization of 403Nb steel occur at high temperature. The compositional phases include α-Fe, Cr23C6 and a small amount of NbC. Among them, the carbide particles coarse, uneven distribution. After quenching at 1050 ℃, lath martensite and residual NbC were obtained. With the increase of quenching temperature, the grains grow up. When the temperature reaches 1150 ℃, there are more δ ferrite along the grain boundary. Adopting optimized heat treatment process, that is, quenching at 1100 ℃ and tempering at 650 ℃, a large amount of nanocrystalline Cr23C6-based carbides are precipitated in the original martensite lath and slats. At this moment, the working temperature and creep of steel Variable life can be greatly improved. The paper elaborates the formation mechanism of steel organization.