脉冲磁场-机械振动复合作用下K4169高温合金凝固组织的细化

Microstructure Refinement of Superalloy K4169 with Compound Treatment of Pulsed Magnetic Field and Mechanical Vibration

对比研究了未处理、脉冲磁场处理、机械振动处理和脉冲磁场-机械振动复合处理对K4169高温合金凝固组织和力学性能的影响,并考察了复合处理条件下不同的脉冲电压、脉冲频率及浇注温度时合金的初生相形貌。结果表明：经脉冲磁场-机械振动复合处理后,合金的晶粒尺寸由4.5 mm细化至0.98 mm,断面等轴晶比例由36%提高至96%,且细化效果均好于单一的脉冲磁场处理或机械振动处理,同时合金的抗拉强度和延伸率较常规铸造条件下分别提高了49.2%,37.3%。随着脉冲电压或脉冲频率增加,合金的初生相逐渐退化,由发达的树枝晶变成细小的等轴晶或蔷薇状晶体。在1380~1530℃范围内,随浇注温度的提高,复合处理后合金的初生相不断细化。

Effects of no treatment, pulsed magnetic field （PMF） treatment, mechanical vibration treatment and compound treatment of pulsed magnetic field and mechanical vibration on the solidified structure and mechanical properties of superalloy K4169 were studied comparatively. Morphologies of primary phase of the alloy with different pulse voltages, pulse frequencies and pouring temperatures under the conditions of compound treatment were investigated. The results show that average grain size of the alloy is refined from 4.5 mm to 0.98 mm, and the fraction of equiaxed grains of the alloy is increased from 36% to 96% by compound treatment. Refinement effect of solidified structure by compound treatment is more efficient than that of pulsed magnetic field treatment or mechanical vibration treatment. Meanwhile, tensile strength and elongation of the alloy with compound treatment compared with the alloy in traditional condition increase by up to 49.2% and 37.3%, respectively. With the increase of the pulse voltage or frequency, primary phase of the alloy degrades gradually from well-developed dendrites into fine equiaxed grains or rosette crystals. When the pouring temperature is 1380-1530 ℃, the increase of pouring temperature enhances the refinement effect of compound treatment.