铁道建筑

对铸造及锻制高锰钢试件开展爆炸硬化试验，分析爆炸硬化后其硬度、拉伸、冲击性能及显微组织的变化规律，并从爆炸硬化机理角度分析产生性能变化的原因。结果表明：仅对轨头顶面进行爆炸可获得较高的浅表硬度，但硬化层深度有限；引入侧面爆炸可减小硬度梯度，形成稳定的中心高硬度带。高锰钢硬化特征受原始组织和断面尺寸的影响显著，相同条件下，铸造高锰钢硬化深度大，易实现全断面硬化；而锻制高锰钢硬化深度浅，易获得较高的浅表硬度。相比于大断面，小断面的硬化效果强且范围广。爆炸引起硬化区域屈服强度升高及塑性、韧性小幅下降。变形带的形态及分布变化是引起炸后性能变化的主要原因。

Explosion hardening experiments were carried out on cast and forged high-manganese steel specimens. The variation laws of hardness， tensile properties， impact properties and microstructure of high manganese steel after explosive hardening were systematically analyzed， and the intrinsic causes of performance evolution were revealed from the perspective of explosive hardening mechanism. The results indicate that only subjecting the rail head's top surface to explosion hardening can obtain high superficial hardness， but results in a limited hardening depth. Furthermore， introducing explosions on the rail head sides reduces the hardness gradient and forms a stable central high-hardness zone. The explosion hardening behavior of high-manganese steel is significantly influenced by its microstructure and cross-sectional dimensions. The cast high-manganese steel achieves a greater hardening depth and full-section hardening， whereas the forged high-manganese steel attains a shallower depth but higher superficial hardness under identical explosion conditions. The smaller cross-sections exhibit more pronounced and extensive explosive hardening effects compared to the larger rail cross-sections. In addition， explosion hardening leads to an increase in yield strength and a decrease in plasticity and toughness in the hardened areas. Microstructural observations reveal that the distribution density of deformation bands are the primary reasons for the property changes in the exploded regions.