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采用50%返回料+50%新料的新工艺熔炼镍基K4169合金,进行了4次返回料的熔炼试验。采用金相显微镜及扫描电镜对新料合金及返回料合金的微观形貌进行了观察,用直读光谱仪对不同返回次数的合金进行了化学成分分析、对其力学和持久性能进行测试,研究了返回料熔炼对合金化学成分、微观组织及力学性能的影响。结果表明:随返回次数增加,化学成分无明显变化,合金的气体含量略呈下降趋势且总含量低于40×10-6,返回料冶炼过程中可不添加B和Zr。K4169合金凝固组织为典型枝晶结构,返回料对K4169合金的铸态枝晶组织没有明显影响。MC型碳化物及Laves相在热处理过程中部分分解,析出针片状δ相,在所有元素中,Nb的偏析最为严重,通过适当延长固溶处理时间可提高元素Nb的分布均匀性和抑制δ相的生成。返回料合金的室温拉伸强度及屈服强度随返回次数增加略有增加,合金的持久寿命较新料合金略有降低,但均明显超过现有技术标准规定的要求。熔炼的返回料合金具有良好的中温塑性,总体上与新料的质量水平相当。返回料合金的铸造性能与新料相当,可以代替新料用于铸件生产。
Nickel-based K4169 alloy was melted by a new process of 50% return material and 50% new material, and the melting test of 4 return materials was carried out. The microstructure of the new alloy and the retrograde alloy was observed by optical microscopy and scanning electron microscopy. The chemical compositions of the alloys with different numbers of return were analyzed by direct reading spectrometer. The mechanical properties and durability of the alloys were tested. The effect of smelting on the chemical composition, microstructure and mechanical properties of the alloy was studied. The results showed that with the increase of the number of return cycles, there was no obvious change in the chemical composition. The gas content of the alloy decreased slightly and the total content was less than 40 × 10-6. B and Zr were not added in the smelting process. The solidified structure of K4169 alloy is a typical dendritic structure, and the return material has no obvious effect on the as-cast dendritic structure of K4169 alloy. MC type carbides and Laves phase partially decomposed and precipitated needle-like δ phases during heat treatment. The segregation of Nb is the most serious among all the elements. By appropriately prolonging the solution treatment time, the distribution uniformity of Nb and the δ Generation of phase. The tensile strength and yield strength of the return alloy at room temperature increased slightly with the increase of the number of return cycles, and the durable life of the alloy was slightly lower than that of the new alloy, all of which significantly exceeded the requirements of the existing technical standards. Melting the return material alloy has good temperature plasticity, generally with the new material quality level quite. The casting material of the return alloy is equivalent to the new material, which can replace the new material for casting production.