压实工艺对大型SA508Ⅲ钢铸锭内部孔洞闭合的影响

Effect of Compaction Technology on Internal Cavity Closure of Large SA508Ⅲ Steel Ingot

使用刚塑性有限元模拟分析了等效应变(εe)、应力三轴比(Tx)、静水压力积分值(Q)等三种孔洞闭合评价方法对孔洞闭合的影响。以Q作为孔洞闭合标准,对 SA508Ⅲ钢大型铸锭内部孔洞压实工艺进行了优化。结果表明:Q值比εe、Tx更适用于评判孔洞闭合的效果,孔洞闭合临界值(Qc)随着孔洞直径比 Rv 的增加而增加,当 1%≤Rv≤4%时,Qc值从0.313增加到0.529;当4%<Rv≤8%时,Qc值为定值 0.529;当 8%<Rv≤10%时,Qc值从0.529 增加到0.754。“WHF(宽砧强力压下锻造)拔长+镦粗+二次 WHF 法拔长”工艺能有效实现 SA508Ⅲ钢大型铸锭内部孔洞的压实,在Rv≤8%时,铸锭压实长度比(铸锭主体压实长度/铸锭主体总长度)为 100%;当 Rv由8%增加到10%时,铸锭压实长度比为87.5%。

The effects of three kinds of void closure evaluation methods (equivalent strain εe, stress triaxial ratio Tx and hydrostatic pressure integral value Q) on void closure were analyzed by using rigid-plastic finite element simulation. Taking Q as the standard of cavity closure, the compaction process of the inner hole of the SA508Ⅲ large steel ingot was optimized. The results show that Q-value is more suitable to evaluate the effect of void closure than εe and Tx. The critical value of void closure (Qc) increases with the increase of the void diameter ratio Rv. When 1%≤Rv≤4%, the Qc value increases from 0.313 to 0.529;when 4%<Rv≤8%, the Qc value is a constant of 0.529;when 8%<Rv≤10%, the Qc value increases from 0.529 to 0.754. The "WHF (wide die heavy blow forging) cogging + upsetting + secondary WHF cogging" process can effectively realize the internal cavity compaction of large SA508Ⅲ steel ingot. When the void diameter ratio Rv≤8%, the ingot compaction length ratio (ingot body compaction length / total length of the ingot body) is 100%;when the Rv increases from 8% to 10%, the ingot compaction length ratio is 87.5%.