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一般认为亚共析钢中魏氏组织降低机械性能,尤其是不利于冲击韧性。近年来研究结果则认为魏氏组织可以提高机械性能,也有人认为具有魏氏组织的亚共析钢,由于冷却速度快,增加了珠光体量,细化了铁素体晶粒,从而抵销了针状铁素体的不良影响。另一些人指出切变机制使针状铁素体中有较高密度的位错和较细的亚结构,提高了钢的机械性能。本文根据对裂纹扩展行为的观察,探讨铁素体影响钢的机械性能的原因。本实验采用25铸钢作试样,其化学成分(wt-％)为:C 0.28,Si 0.37,Mn 0.61,S
Generally believed that sub-eutectoid Wei organization reduce mechanical properties, especially not conducive to impact toughness. In recent years, the results of the study suggest that Widmanstatches can improve the mechanical properties. Some people think that the hypo-eutectoid steel with Widmanstatten results in faster cooling, increasing the amount of pearlite and refining the ferrite grains, thus offsetting The acicular ferrite adverse effects. Others pointed out that the shear mechanism causes higher density of dislocations and finer substructures in acicular ferrite and increases the mechanical properties of the steel. Based on the observation of the crack propagation behavior, this paper discusses the reason why ferrite affects the mechanical properties of steel. The experiment uses 25 cast steel as the sample, the chemical composition (wt-%): C 0.28, Si 0.37, Mn 0.61, S