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C-HRA-3镍基耐热合金真空感应熔炼脱氧脱氮热动力学研究
Study on Thermodynamics and Kinetics of Deoxidation and Denitrification of C-HRA-3 Nickel Base Heat Resistant Alloy during Vacuum Induction Melting
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- DOI:
- 作者:
- 李龙飞,林腾昌,梁 强,何西扣,陈正宗,陈 琨
Li Longfei, Lin Tengchang, Liang Qiang, He Xikou,
- 作者单位:
- 钢铁研究总院有限公司
Department of Metallurgical Technology Research
- 关键词:
- C-HRA-3耐热合金;脱氧;脱氮;热动力学;真空感应熔炼
C-HRA-3 heat resistant alloy; deoxidation; denitrification; thermodynamics and kinetics; vacuum induction melting
- 摘要:
- 为探明真空感应熔炼C-HRA-3镍基耐热合金脱氧和脱氮过程的热动力学规律,采用VIM-50型真空感应炉熔炼高纯合金原料,严格控制冶炼条件并取过程样检测,借助物理化学原理对试验结果进行分析。结果表明,精炼温度升高,C-HRA-3合金液中的平衡碳氧积增大而氮的平衡溶解度降低,真空度提高同时降低氧和氮的平衡溶解度。在实验冶炼条件(1582 °C,2.7 Pa)下,平衡[O]和[N]含量分别为3.73 ×10-4 wt.%和23.66 ×10-4 wt.%。随着精炼期延长,[O]、[N]含量逐渐降低,精炼后期时受MgO坩埚分解影响[O]含量二次升高。C-HRA-3合金真空碳脱氧反应和脱氮反应的限制性环节分别为[O]在液相边界层中的扩散和[N]原子在界面处的化学反应,经计算[O]在液相边界层中的平均传质系数k[O]为2.68×10-3 cm/s,脱氮反应为二级反应,反应表观速率常数为0.733 cm/s。
In order to verify the thermodynamics and kinetics law of deoxidation and denitrification of C-HRA-3 nickel base heat resistant alloy, a VIM-50 furnace was used to melt high-purity alloy raw materials with specific proportion. During the experiment, the smelting conditions, such as temperature and pressure, were strictly controlled and the process samples were taken out of the liquid alloy. The test results were analyzed by theories of physical and chemical metallurgy. The results show that with the increase of refining temperature, the carbon-oxygen equilibrium increases and the equilibrium nitrogen solubility decreases in liquid C-HRA-3 alloy. However, the increase of vacuum degree could reduce the equilibrium solubility of oxygen and nitrogen simultaneously. Under the refining conditions of 1582 °C and 2.7 Pa, as the carbon content in liquid alloy is 0.01 wt.%, the calculated equilibrium oxygen and nitrogen contents are 3.73 ×10-4 wt.% and 23.66 ×10-4 wt.% respectively. With the extension of refining period, the contents of [O] and [N] gradually decrease, and the content of [O] increases again affected by the decomposition of MgO crucible in the later stage of refining. By dynamic analysis, the limiting step of vacuum carbon deoxidation is the diffusion of [O] atoms from liquid boundary layer to reaction interface, while the limiting step of vacuum denitrification is the interfacial chemical reaction of [N] atoms. After calculation, the average mass transfer coefficient of [O] in the liquid boundary layer, k[O], is equal to 2.68×10-3 cm/s. The vacuum denitrification reaction is proved to conform to the law of second-order reaction and the apparent rate constant of reaction is 0.733 cm/s.