Perfection of Fe–C–Si–Мn–Сr–W–V system flux-cored wire composition for surfacing of hot rolling mill rollers by introducing titanium in it

Abstract

Rollers for hot rolling mills are hardened by surfacing operation by flux-cored wire ПП-Нп-35В9Х3СФ due to GOST 26101–84. The deposited layer has a high resistivity against abrasion, but its thermal endurance is comparatively low, therefore rollers surfaced by this type of wire often failed because of formation of fire crack network and spalling. It was established that the structure nonuniformity of the deposited metal can be decreased by introducing of titanium into the flux-cored wire. The effect of introducing titanium into flux-cored wire of the Fe–C–Si–Мn–Сr–W–V system on the properties of the deposited layer has been studied. It was shown that metal structure with the addition of titanium represents martensite formed within the boundaries of the former austenite grain, a small amount of residual austenite in the form of separate areas and thin layers of δ-ferrite. The microstructure of the samples contains a carbide network. An increase in the titanium content in the deposited layer contributes to a decrease in the size of the martensite needles, as well as the size of the former austenite grain. The microstructure of the samples contains medium-acicular and fine-acicular martensite. The size of the martensite needles varies from 2 to 9 microns. It was established that introduction of titanium in the composition of the flux-cored wire in an amount of 0.02–0.13% increases the hardness of the deposited layer and reduces the abrasion of the samples.