锥板镦粗中偏析对锻造裂纹影响的数值模拟

Numerical Simulation of Impact of Segregation on Forging Crack in Cone-plate Upset

某锻造厂核电管板的探伤合格率一直不稳定,2010年以来合格率下降到50%左右。根据对探伤不合格管板取样分析,钢锭中非金属夹杂物没有超标。为了分析核电管板探伤不合格的原因,以锻压数值模拟软件为平台,通过坯料无偏析和有偏析两种不同的数学模型来研究偏析对锻造裂纹的影响。模拟结果表明:在锥板镦粗过程中,坯料无偏析时,损伤因子、等效应变和最大主应力均较小;坯料有偏析时,偏析周围损伤因子、等效应变的梯度变化和最大主应力的值相对于坯料无偏析时较大。偏析的存在使得金属材料变形不均匀,容易出现锻造裂纹。

The quality of nuclear power tube plate in a forging plant is unstable at all times, for flaw-detection datum of forging are lower. Since 2010, the qualified rates drop to about half. According to the testing of unqualified tube plate sampling, steel ingot non-metal inclusions are not exceeded. In order to analyze the reason of the unqualified nuclear power tube plate, two different mathematical models of the blank with and without segregation were established to research the effect of segregation on the forging cracks by using the forging numerical simulation software. The simulation results show that the damage, the equivalent strain and the maximum principal stress are relatively small when without segregation appears in the blank; and the damage, the equivalent strain gradient and the value of the maximum principal stress are relatively larger comparing with the blank without segregation when it appears in the blank, in the process of the cone-board upsetting. The existence of segregation makes the metal material distortion uneven, prone to forging crack.