双联法制备100 kg级匀质TiNi合金铸锭

Preparation of 100 kg Class Uniform TiNi Alloy Ingots by Duplex Process

目前国内工业生产的等原子比TiNi合金铸锭约20 kg。为提高铸锭单重及其相转变温度的均匀性,采用真空感应熔炼(VIM)与真空自耗重熔(VAR)相结合的方法生产100 kg级TiNi合金铸锭。对双联法制备φ160 mm-120 kg的Ti-50.9Ni合金铸锭进行化学成分与相转变温度的检测。结果表明:Ti-50.9Ni合金降温时马氏体开始转变温度Ms=-53℃,后续升温过程中奥氏体终了转变温度A_f=-18℃,属于低温TiNi二元合金。VIM+VAR二次铸锭的化学成分均匀,C、O元素含量降低。VIM+VAR二次铸锭中C含量显著降低,约为VIM一次铸锭的1/8,提高了相转变温度A_f的均匀性,偏差达到±5℃的水平。分析不同熔炼方法对TiNi合金相转变温度均匀性的影响,总结出双联法的优势互补性。VIM制备的TiNi合金铸锭成分均匀,VAR进一步精炼、提纯、增大锭型,提出了制备大型匀质TiNi合金铸锭的新思路。

At present, the weight of equal atom ratio TiNi alloy ingots are about 20 kg produced by domestic industry. In order to improve the single weight of the ingot and the uniformity of phase transition temperature, 100 kg TiNi alloy ingot is produced by the combination of vacuum induction smelting(VIM) and vacuum self-consumption remelting(VAR). The chemical composition and phase transition temperature of φ160 mm-120 kg Ti-50.9Ni alloy ingot prepared by the duplex process were detected. The results show that when the Ti-50.9Ni alloy is cooled, the martensite begins to change at the temperature Ms=-53℃, during the subsequent warming process, the austenite terminal transition temperature A_f is-18℃, and the Ti-50.9Ni alloy belongs to the low temperature TiNi binary alloy. The chemical composition of VIM+VAR secondary ingot is uniform, the element contents of C and O in the secandry ingot reduce. The content of C in VIM+VAR secondry ingot significantly reduces, which is about 1/8 of the VIM ingot. The uniformity of the phase transition temperature A_f is improved and the deviation reaches ±5℃. The influence of different smelting methods on the uniformity of TiNi alloy’s phase transition temperature was analyzed, and the advantages and complementarities of the duplex process were summarized.The components of TiNi alloy ingots prepared by VIM is uniform, and the ingots were further refined, purified, and enlarged by VAR. A new idea for preparing large uniform TiNi alloy ingots was proposed.