3C-15Cr-0.75Si系高铬铸铁锰合金化规律的热力学分析

基于Thermo-Calc软件的热力学平衡相计算,研究了高铬铸铁中锰的合金化规律及其对组织的影响.结果表明,锰虽然对高铬铸铁中的各相数量影响不大,但一定数量的锰存在促使合金元素在奥氏体和碳化物两相中的重新分配,并降低平衡相的转变温度;在平衡条件下3C-15Cr-4Mn-0.75Si系高铬铸铁中莱氏体数量约占87%,而非平衡条件下M7C3型碳化物数量在23%～32%之间,且奥氏体中锰铬互替现象保证了奥氏体的稳定性和加锰高铬铸铁的淬透性.Thermo-Calc软件计算预测结果与现有试验数据基本相符.

Thermodynamic Analysis of Manganese Alloying Rule in 3C-15Cr-0.75Si System High Chromium Cast Iron

The manganese alloying rule and its effect on the microstructure in high chromium cast iron have been studied based on thermodynamic equilibrium phase calculations using Thermo-Calc software. The results show that the addition of certain manganese in high chromium cast iron leads to a re-partitioning of alloy elements between austenite and carbide and a dropping in equilibrium phase transformation temperature although it's inappreciable for the influence of manganese on mass fractions of every phase in this cast iron. There is about 87 percent ledeburite under thermodynamic equilibrium condition and 23 to 32 percent M_7C_3 type carbide under thermodynamic non-equilibrium condition in the microstructure of 3C-15Cr-4Mn-0.75Si system high chromium cast iron. Furthermore, the improvement of austenite stability and hardenability of manganese alloyed high chromium cast iron may been expected because there is a substitution between manganese and chromium that has been suggested by thermodynamic calculations. The predictions obtained with Thermo-Calc software are primarily in agreement with the available experiments.