稀土对Fe-43Ni膨胀合金热塑性的影响

Effect of rare earth on hot ductility of Fe-43Ni expansion alloy

Fe-43Ni膨胀合金因其凝固组织粗大导致合金的热塑性较差,在热加工过程中开裂严重。针对该问题,通过Gleeble高温拉伸试验、SEM、EDS等手段研究了稀土Ce及其含量对Fe-43Ni膨胀合金组织和热塑性的影响。结果表明,常规Fe-43Ni合金在温度小于1000℃时热塑性较差。添加质量分数为0.025%的Ce,合金中形成了大量的Ce_(2)O_(3)和Ce_(2)O_(2)S稀土夹杂物,合金的热轧组织显著细化。850~1100℃温度区间的热塑性明显提高,热塑性良好的温度区间向低温区扩大了50℃。但是添加质量分数为0.063%的Ce时,合金铸锭在热轧过程即发生开裂,热塑性严重恶化。稀土添加适量可提高合金的热塑性,反之过量会恶化热塑性。试验结果为大生产中热轧稀土微合金化Fe-43Ni膨胀合金提供一定的指导。

Fe-43Ni expansion alloy has poor hot ductility due to its coarse solidification structure, and often cracks seriously during hot rolling process. Focus on this problem, the effect of Ce content on hot ductility of Fe-43Ni expansion alloy was studied using Gleeble thermal mechanical simulator, SEM and EDS. The results show that the hot ductility of conventional Fe-43Ni expansion alloy is poor when the temperature is less than 1000 ℃. With the addition of 0.025%Ce, a large number of Ce_(2)O_(3) and Ce_(2)O_(2)S rare earth inclusions are formed in the alloy, the microstructure morphology of hot rolled plates are refined and the hot ductility of alloy is improved in the temperature range of 850-1100 ℃, moreover, the high temperature ductility range has expanded 50 ℃ to the lower temperature zone. However, the alloy ingot cracks during hot rolling and the hot ductility of alloy seriously deteriorates with the addition of 0.063%Ce. Adding a suitable amount of Ce could improve the hot ductility of alloy, while excessive Ce would deteriorate the hot ductility. The experimental results provids some guidance for rare earth microalloying Fe-43Ni expansion alloy during the hot rolling process of large-scale productions.