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对两种不同晶粒度的低合金高强钢(WCF-62)的试样在常温下获得均匀预应变后(0～20%),在-125 ℃下对预应变和未预应变的试样进行了四点弯曲试验,测量了宏观和微观力学参数,以及断口参数.并结合有限元计算所得的不同预应变条件下的缺口前端的应力应变场分布,分析了预应变对不同晶粒度低合金高强钢缺口试样断裂行为的影响.结果表明:粗晶和细晶材料在室温预应变3%后,缺口韧性有明显的降低,但是随预应变进一步增加,缺口韧性基本保持不变.原因是预应变3%后两种材料解理断裂都转变为起裂控制.
The samples of two kinds of low alloyed high strength steel (WCF-62) with different grain sizes were homogenized (0 ~ 20%) at room temperature, pre-strained and non-pre-strained Four-point bending test was carried out, and the macroscopic and microscopic mechanical parameters as well as the fracture parameters were measured. In addition, the stress-strain field distribution under the different pre-strain conditions obtained by finite element method was analyzed. The results show that the ductility of the coarse and fine grained materials decreases obviously after pre-strain of 3% at room temperature, but the notch toughness remains unchanged with the further increase of the pre-strain. After the pre-strain is 3%, the cleavage and cleavage of the two materials are both changed into the initiation control.