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.

中文翻译：

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典型壳钢在冲击载荷作用下的微观断裂机理

本研究的目的是研究应变速率和金相组织对典型壳钢材料在冲击载荷下的断裂模式和断裂模式的影响。使用弹道枪发射球形钨合金弹丸以撞击目标 50SiMnVB 和 60Si2Mn 钢板。在金相显微镜下观察不同靶板上裂纹的形态特征，分析应变率和金相组织对断裂方式和断裂模式的影响。结果表明，当应变率较低时，材料在冲击载荷作用下主要产生韧性断裂和脆性穿晶断裂；当应变率相对较高时，冲击载荷作用下的主要断裂方式是沿晶断裂和解理断裂。此外，在较高的应变速率下，冶金形式主要影响材料的断裂模式，回火屈氏体比回火索氏体更容易产生剪切和拉伸断裂的混合物。所得结果为壳钢材料的微观断裂机理提供了实验依据，并在一定程度上揭示了断裂与材料的应变率和微观结构之间的相关性。