Surface Hardening Treatment for C.P. Titanium and Titanium Alloys in Use of Ar–5%CO Gas
Surface Hardening Treatment for C.P. Titanium and Titanium Alloys in Use of Ar–5%CO Gas
复制标题
使用 Ar–5%CO 气体对 C.P. 钛及钛合金进行表面硬化处理
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
C. Ouchi
中科院分区：
文献类型：
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作者：
Y. Z. Kim;T. Murakami;T. Narushima;Y. Iguchi;C. Ouchi
在973 ~ 1123 K温度范围内，研究了工业纯钛及钛合金在Ar-5%CO气体中的表面硬化。所用钛材料为Ti-4.5%Al-3%V-2%Mo-2%Fe的α+β型合金（SP-700）和Ti-15%V-3%Cr-3%Sn-3%Al的β型合金（Ti-15-333）。与Ar-20%CO_2气体相比，Ar-5%CO气体的氧化和表面硬化明显减少。表面硬化的最大表面硬度和硬化层的深度从硬度分布剖面在次表面区域进行了评价。前者在C. P.钛中最高，在Ti-15-333合金中最低;后者在Ti-15-333合金中最深，在C. P.钛中最浅。C. P.钛的表面硬化是由在次表面区域中富集的氧和碳的固溶体硬化引起的。SP-700和Ti-15-333合金亚表面区中这些相的富集分别导致α+β两相中α相体积分数的增加或β相向α+β两相的相变，表面硬化主要由相富集硬化的α相体积分数控制。另一种β型钛合金Ti-15%Mo-5%Zr-3%Al比Ti-15-333合金具有更显著的表面硬化。利用电子探针（EPMA）获得的氧、碳浓度分布和一维扩散模型的计算结果对上述结果进行了分析和讨论。
Surface hardening of C.P. (commercially pure) titanium and titanium alloys in use of Ar–5%CO gas was investigated in the temperature range between 973 K and 1 123 K. Titanium materials used were α+β type alloy of Ti–4.5%Al–3%V–2%Mo–2%Fe (SP-700) and β type alloy of Ti–15%V–3%Cr–3%Sn–3%Al (Ti-15-333). Oxidation accompanied with surface hardening in use of Ar–5%CO gas is much reduced compared with that of Ar–20%CO2 gas. Surface hardening was evaluated by both of the maximum surface hardness and hardening layer depth obtained from hardness distribution profiles in the subsurface region. The former is the highest in C.P. titanium and the lowest in Ti-15-333 alloy, and the latter is the deepest in Ti-15-333 alloy and the shallowest in C.P. titanium. Surface hardening in C.P. titanium is caused by solid solution hardening of oxygen and carbon enriched in the subsurface region. Enrichment of these interstitials in the subsurface region of SP-700 or Ti-15-333 alloys causes the increase of α volume fraction in α+β two phases or phase transformation from β to α+β two phases, respectively, and surface hardening is primarily controlled by volume fraction of α phase hardened by interstitials enrichment. The other β type titanium alloy of Ti–15%Mo–5%Zr–3%Al yields much marked surface hardening over Ti-15-333 alloy. All of these results were analyzed and discussed based on oxygen and carbon concentration profiles, which were obtained by EPMA, and were also calculated by uni-dimensional diffusion model.