Mechanism of Microscopic Fracture of Typical Shell Steel under Impact Loading

Chuan Zhao,Feng Ma,Cean Guo,Xuncheng Guo,Yuhui Sun,Shushan Wang,Andrzej Katunin

doi:10.1155/2022/1508114

Abstract

The aim of the current study was to investigate the effects of strain rate and metallographic structure on the fracture mode and fracture pattern of a typical shell steel material under impact loading. A ballistic gun was used to launch a spherical tungsten alloy projectile to impact target 50SiMnVB and 60Si2Mn steel plates. The morphological characteristics of the cracks on different target plates were observed under a metallurgical microscope, and the effects of the strain rate and metallographic structure on the fracture mode and fracture pattern were analyzed. The results showed that when the strain rate was relatively low, the material mainly produced ductile fracture and brittle trans-granular fracture under impact loading; when the strain rate was relatively high, intergranular fracture and cleavage fracture were the main modes of fracture under impact loading. In addition, at higher strain rates, the metallurgical form mainly influenced the pattern of fracture of the material, with tempered troostite being more likely to produce a mixture of shear and tensile fractures than tempered sorbite. The results obtained provide an experimental basis for the mechanism of microscopic fracture of shell steel materials and, to a certain extent, reveal the correlations between fragmentation and the strain rate and microstructure of the material.

Highlights

To adapt to the harsh firing environment and in consideration of the cost, the ammunitions of most barreled weapons, such as grenades and mortar shells, are made of monolithic structures, which produce natural fragments of varying shapes and masses upon explosion. e fragmentation results of the shell under the action of a blast load conform to certain statistical patterns [1]. rough the tireless efforts of many researchers [2,3,4], the mass distribution behaviors of natural fragments were summarized into the generally recognized and accepted Weibull distribution model (Mott distribution is its special case). e Weibull distribution is a two-parameter distribution with two control parameters: the scale parameter μ and the shape parameter ß
Effect of Strain Rate on the Fracture Mode. e fracture of materials under impact loading can be divided into ductile fracture and brittle fracture [11], and brittle fracture can be further divided into intergranular fracture, trans-granular fracture, and cleavage fracture based on the relationship between the crack and the grain boundary
The metallurgical structure form and strain rate of the target plate were important factors affecting the fracture pattern of the material under the action of an impact load

Summary

Introduction

To adapt to the harsh firing environment and in consideration of the cost, the ammunitions of most barreled weapons, such as grenades and mortar shells, are made of monolithic structures, which produce natural fragments of varying shapes and masses upon explosion. e fragmentation results (i.e., the distribution of the number of fragments with their mass) of the shell under the action of a blast load conform to certain statistical patterns [1]. rough the tireless efforts of many researchers [2,3,4], the mass distribution behaviors of natural fragments were summarized into the generally recognized and accepted Weibull distribution model (Mott distribution is its special case). e Weibull distribution is a two-parameter distribution with two control parameters: the scale parameter μ and the shape parameter ß. Rough the tireless efforts of many researchers [2,3,4], the mass distribution behaviors of natural fragments were summarized into the generally recognized and accepted Weibull distribution model (Mott distribution is its special case). Zhang et al [9] proposed that the shape parameter ß was related to the homogeneity of the fragments and investigated the influence of the shell shape on μ. E above studies showed that it is still an unsolved problem to analyze in detail the factors influencing the values of the control parameters of the distribution model, to specify their physical meanings, and to establish a calculation method that can predict their values more accurately. To solve the above problems, an in-depth study of the fracture mechanism of shells is required

Methods

Discussion

Conclusion