：##3对45，T8和GCr15三种球化钢的力学性能、断裂及微观损伤机理进行了研究.结果表明，碳化物粒子的存在引起的孔洞形校及长大是导致这类材料断裂破坏的主要原因；材料的孔洞体积分数随应变而增加，且含有较多碳化物粒子的材料孔洞体积分数增长较快；孔洞损伤可导致材料的软化，推导出碳化物粒子和孔洞损伤影响的等效应变硬化指数以及断裂应变的解析表达式。断裂应变的解析表达式为 : ## 3 The mechanical properties, fracture and micro-damage mechanisms of 45, T8 and GCr15 three ball steels were studied.The results show that the hole shape and growth caused by the existence of carbide particles lead to the fracture of these materials The main reason of vandalism is that the pore volume fraction of material increases with strain and the volume fraction of pores with more carbide particles increases rapidly. The pore damage can lead to the softening of the material and the influence of carbide particles and pore damage can be deduced Elastic hardening exponent and analytical expression of strain at break. The analytical expression of strain at break is