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探讨了35SiMnVN和35SiMnVTiN高强度非调质钢的强韧性能与显微组织间的关系。测定了析出相的类型和组成,测试和计算了冲击、拉伸状态下裂纹的形核能与扩展能,并通过SEM研究了断面形貌。结果表明:在钢中加入微量的Ti元素可使先共析铁素体量增多,促使V的析出,V的最大析出量不超过钢中V含量的60％,V的析出强化增量约为固溶强化增量的10～30倍;在冲击状态下,所有组织的钢均为准解理断裂,但在静态拉伸时,F-P组织的钢为剪切断裂,B组织的钢仍为准解理断裂。
The relationship between the toughness and the microstructure of 35SiMnVN and 35SiMnVTiN high strength non-quenched and tempered steels was discussed. The type and composition of the precipitated phase were measured. The nucleation energy and expansion energy of the crack under impact and tensile conditions were tested and calculated. The morphology of the fracture surface was also studied by SEM. The results show that adding Ti in the steel can increase the amount of proeutectoid ferrite and promote the precipitation of V. The maximum precipitation amount of V does not exceed 60% of the V content in steel. The precipitation enhancement increment of V is about In the case of impact, the steels of all the structures are quasi-cleavage fractures. However, in the static tensile tests, the FP-steels are shear-fractured and the steels of the B-steels are still accurate Cleavage fracture.