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大锻件内部脆性夹杂物边界裂纹是影响其疲劳寿命与冲击性能的主要缺陷。热锻过程中脆性夹杂物周围区域的应力场是影响裂纹闭合的关键因素。为了研究应力场对裂纹闭合的影响,给出了平均球应力度的定义及数学表达式。以平均球应力度为判据,使用Deform软件研究了应力场对脆性夹杂物边界裂纹的影响规律。结果表明:脆性夹杂物边界裂纹对平均球应力度的相关度高;随平均球应力度代数值的减小,脆性夹杂物边界裂纹的尺寸减小,当平均球应力度代数值小于-2.32时,脆性夹杂物边界微裂纹完全闭合。在Gleeble-3180热模拟试验机上,利用专门的试件和型砧进行了1220℃热压缩变形试验,试验结果与数值模拟结果基本吻合。
Large forging internal brittle inclusions boundary cracks are the main defects affecting their fatigue life and impact properties. The stress field around the brittle inclusions during hot forging is the key factor that affects the crack closure. In order to study the effect of stress field on crack closure, the definition and mathematical expression of average ball stress degree are given. With the average ball stress as the criterion, Deform software was used to study the influence of stress field on the boundary cracks of brittle inclusions. The results show that the correlation between the brittle inclusions and the average ball stress is high. With the reduction of the average algebraic value of the average ball stress, the size of the boundary cracks in the brittle inclusions decreases. When the mean spherical algebraic value is less than -2.32 , Brittle inclusions border micro-cracks completely closed. On the Gleeble-3180 thermal simulation testing machine, a special specimen and a type anvil was used to carry out the hot compression deformation test at 1220 ℃. The experimental results are in good agreement with the numerical simulation results.