Newly developed high-strength martensitic stainless steel for the sniper rifle barrel with high shooting accuracy

Abstract

With the increasing requirements for the shooting accuracy of the sniper rifle, steel combined with excellent high-temperature strength, low-temperature toughness, and extraordinary corrosion resistance is desirable for the barrel material of the sniper rifle with high accuracy and a long lifespan. In this study, martensitic stainless steel 2Cr11Ni2Mo2WV (MPS700A) was developed by introducing Mo, W, and V into the currently used 2Cr13 steel. The 600 °C tensile tests demonstrated that the ultimate tensile strength of MPS700A reached 767 MPa, which was 46.4 and 97.2 % higher than those of 2Cr13 and 30SiMn2MoV, respectively. Meanwhile, the −40 °C impact toughness of MPS700A reached 88 ± 4 J/cm2, which was 20.5% higher than that of 2Cr13 and comparable to that of 30SiMn2MoV. The intralath precipitation of ellipsoidal M2C nano carbides was observed in MPS700A after tempering, which followed a Dyson orientation relationship (OR) of (01¯12)M2C//(200)α with the martensitic matrix. After deformation at 600 °C, such a Dyson orientation relationship (OR) was maintained, and the M2C in MPS700A exhibited higher thermal stability than the M3C in 2Cr13, which hinders the dislocation movement and contributes to the higher strength of MPS700A at 600 °C. The fine martensitic laths and homogeneously dispersed M2C nano carbides also contributed to the higher impact toughness of MPS700A than that of 2Cr13. Additionally, the salt spray test indicated that the mass loss of MPS700A was 1.72 ± 0.24 g m−2 at 72 h, which was 95.6% lower than that of Cr-plated 30SiMn2MoV and comparable to that of 2Cr13. Based on these results, we demonstrate that MPS700A exhibits high strength up to 600 °C, excellent impact toughness at low temperatures, and outstanding corrosion resistance, making it a promising gun barrel material for sniper rifles with long lifespans and high shooting accuracy.