Combustion Characteristics and Mechanisms of Two Gun Barrel Steels by Promoted Ignition Combustion

Abstract

ABSTRACT The combustion characteristics of 25Cr3Mo2NiWVNb (MPS700V) and 30SiMn2MoV gun barrel steels are investigated in oxygen-enriched atmosphere. For MPS700V, threshold pressure of combustion increases from 0.26 to 0.46 MPa with diameter increases from 2.4 to 4.0 mm, where are higher than that of 30SiMn2MoV in the same size. Three different zones including oxide zone, melting zone, and matrix zone are observed in both 30SiMn2MoV and MPS700V steels. Elements Mo, C in 30SiMn2MoV and Mo, Ni, C in MPS700V are enriched in the melting zone. When pressure is lower than threshold pressure, samples do not entirely burn but numerous ablation pits form on the surface. The average depth and area of ablation pits on MPS700V are less than that on 30SiMn2MoV under the same pressure. Dendritic microstructure is observed around ablation pits in both MPS700V and 30SiMn2MoV. For MPS700V, dendritic microstructure is composed by Mo2C and γ-Fe phases, where Mo, C are enriched in the dendrite and Ni is enriched in interdendrite. For 30SiMn2MoV, dendritic microstructure is composed by Mo2C and Fe3C carbides and ferrite, where Mo, C are enriched in the dendrite. Based on above, the difference of combustion mechanism for 30SiMn2MoV and MPS700V is discussed.