【摘要】 本文探讨硅钢在挛晶机制下解理断裂微观模型。为此,进行光滑拉伸试验,切口试样四点弯曲试验,测定了不同晶粒度的Fe、1.5Si-Fe、3Si-Fe、4Si-Fe钢的屈服强度和解理断裂强度。本文阐述了硅钢的屈服强度和解理断裂强度在孪晶机制下的特点。在低温时,屈服强度有一段不随温度变化;解理断裂强度随温度下降而减小。本文提出硅钢孪晶引发的解理断裂的微观机制是:在高应力控制下“交叉孪晶成核—扩展控制”的模型,其解理核大小等于孪晶相交宽度。还提出在高应变下,由于挛晶的通道断裂,存在“交叉孪晶成核—微裂纹—扩展”模型。利用Griffith公式计算了一对交叉孪晶成核后扩展的有效表面能为4～12焦耳/米~2。更多还原

【Abstract】 This paper discusses the microscopic model for cleavage fracture of Si-iron under twinning deformation condition.Smooth tensile test and 4-point notch bending test were conducted on steel of Fe, Fe-1.5Si, Fe-3Si, Fe-4Si with various grain sizes in order to determine their yield stress and cleavage stress.When the deformation and cleavage fracture are twin-initiated the yieled stress is essentially independent of temperature and the cleavage-fracture stress reduces with decreasing temperature.The model of microscopic mechanism of cleavage fracture in Si-iron proposed in this paper is twin-initiated and propagation controlled cleavage fracture, i. e. the cleavage crack initiates at the intersection of deformation twins and the propagation of the crack nucleus is the controlling event (by a critical stress criterion); In addition, there is another possible mechanism of cleavage fracture under high nominal strain: the twin-initiated nuclei join together by the so-called "channel-fracture mechanism" and the resulting crack propagation under lower stress.更多还原