Fe-0.06C-12Cr-1.9W-0.5Mo-3.0Co-VNbN耐热钢的显微组织分析

Investigation on the microstructure of Fe-0.06C-12Cr-1.9W-0.5Mo-3.0Co-VNbN heat resistant steel

为进一步提高铁氏体/马氏体耐热钢的高温蠕变强度,试验研究了一种含钴的新型高铬耐热钢:Fe-0.06C-12Cr-1.9W-0.5Mo-3.0Co-VNbN.采用扫描电镜(SEM)、透射电镜(TEM)和X射线衍射(XRD)分析研究了该耐热钢在正火回火状态和650℃长期时效过程中的显微组织.结果表明:在1 100℃×1h正火处理+700℃×1h回火处理状态,钢的显微组织为板条状回火马氏体,在原奥氏体晶界和板条界上有M23C6型碳化物析出,在板条内分布有纳米尺寸的MX相;在650℃长期时效过程中有Laves相(Fe2W)和Z相(CrVNbN)析出,Laves相在原奥氏体晶界和板条界析出.钢的硬度随着时效时间的延长先增加后降低.

A new kind of heat resistant steel with Co Was studied. The microstructure of Fe-0.06C-12Cr-1.9W-0.5Mo-3.0Co-VNbN heat resistant steel has been investigated by the scanning electron microscope （SEM）, transimission electron microscope （TEM） and X-ray diffraction （XRD）. The results show that the microstructure of the steel after normalizing at 1100℃ for 1h and tempering at 700℃ for lh is consisted of tempered lath martensitic structure; M233C6 carbide precipites along grain boundaries and lath boundies while nano-sized MX phase precipitates within lath. During long time ageing at 650℃, Laves phase （Fe2W） and Z phase （CrVNbN） were detected by XRD. Laves phase distributes along grain boundaries and lath boundies. The hardness of the steel increases before 500h aging and then decreases with the prolongation of aging time at 650℃.