Microstructure and carbides characteristics of spray formed 9V high vanadium steels

Abstract

To develop advanced high speed steel with high vanadium content, a kind of vanadium content 9% high speed steel in the form of circular ring was spray formed under certain thermal conditions. The carbides topography of as-cast and as-sprayed 9V steel were observed. The effects of post thermo-mechanical processing (hot isostatic pressing and hot forging) and heat treatment on the microstructure and carbides distribution were investigated. The spray formed 9V steel typically consists of fine, homogeneous and angular-shaped MC carbides with diameters ranging from 1 to 2 μm. Spray formed 9V steel shows an excellent hot workability following increase of forging ratio due to fine homogeneous carbides. After heat treatment, spray formed 9V steel is composed of MC carbides, martensite and retained austenite. The hardness value of heat treated materials is inversely proportional to the volume fraction of residual austenite. Fine dispersed MC carbides have significant influences on the dislocation motion of spray formed 9V steel.

Keywords

spray forming / carbide / 9V steel / hardness / dislocation

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