Optical measurements of phase transition and temperature in adiabatic shear bands in titanium alloys
Optical measurements of phase transition and temperature in adiabatic shear bands in titanium alloys
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DOI：
10.1051/jp4:2000958
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发表时间：
2000-09-01
期刊：
影响因子：
--
通讯作者：
Hervé, P
中科院分区：
文献类型：
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作者：
Ranc, N;Pina, V;Hervé, P
绝热剪切带在高速扭转、压缩和弹道冲击等不同的激发方式下可能出现。剪切带的形成往往是材料破裂的直接前兆。这种塑性变形导致了快速局部化温度梯度。为了产生绝热剪切带，我们建立了动态冲压装置。我们通过光学测量确定了温度和转变相。两个波长的测量使我们能够分离温度和发射率。0.6微米处的测量导致剪切带内的温度变化，5微米处的测量导致材料发射率的变化，从而可以识别相变。对TA6V的实验结果使我们能够指出在剪切带内存在非常高的温度(T-max 1273℃)。我们比较了两种钛合金(TA6V和Ti20V)的发射率变化，发现在TA6V合金的情况下存在α-β相变。
Adiabatic shear bands may occur in different type of solicitation such as high speed torsion, compression, and ballistic impact. The formation of a shear band is often an immediate precursor to rupture of the material. Fast localised temperature's gradient results from this plastic deformation. In order to generate adiabatic shear bands, we have built a dynamic punching device. We determine the temperature and the transition phase by optical measurement. A measure at two wavelengths allows us to dissociate the temperature and the emissivity. A measure at 0,6 mu m leads to the temperature in shear band and a measure at 5 mu m leads to the emissivity variation of the material and allows to identify the phase transition. The experimental results obtained for TA6V have enabled us to point out the existence of very high temperatures (T-max 1273 degrees C) within the shear band. We compare the emissivity variation of two titanium alloys (The TA6V and the Ti20V) and we detect the alpha-->beta phase transition in the case of the TA6V alloy.