45#钢高速冲击穿孔的显微组织

借助烧结的W合金圆柱体垂直冲击60mm厚的45^#热轧钢板实验，利用扫描电镜和光学金相显微镜研究了45^#钢高速冲击穿孔的显微组织。冲击波使穿孔周围的晶粒破碎，冲击引起的材料变形功转变为热能，以及侵彻过程中的摩擦作用，使穿孔表面熔化，靠近熔化区的晶粒发生再结晶。从穿孔表面到钢板内部可分为：熔化快凝层、再结晶细晶层、变形细晶层、形变层和正常基体组织。在细晶层和形变层中，铁素体晶粒的变形量要远远大于珠光体，部分珠光体开裂，其周围形成微裂纹和微孔洞。钢中的硫化锰夹杂在变形中被剧烈拉长。由于铁素体的塑性，钢板的破坏方式为延性扩孔。

MICROSTRUTURE INVESTIGATION OF THE PENETRATION BORE OF 45# STEEL IN HIGH SPEED IMPACTING

The cylinder of sintered W alloy impacted directly on 45# hot-rolled steel plate. The microstructures of penetration bore were investigated by using SEM and Optical Metallography. The grains around the bore were fragmentated by Shock waves. The deformation heat caused by impact and friction during penetration melted the surface of the bore, and the grains nearby recrystalized. The region from the penetration surface to the interior of the armor plate the section can be divided as: melted and rapid solidification layer, recrystallized fine grained layer, deformed fine grained layer, deformed layer and normal matrix. In fine grained layer and deformed layer, the deformation of ferrite grains is far greater than that of pearlites. Some pearlites crazed. and the micro-cracks and micro- holes formed around pearlites. The sulfides in steel, particularly MnS. were drawn acutely parallel to the penetration direction. The deatruct mode of steel plate was ductile expanding bore due to the high ductility of ferrites.