Method for detecting the contamination of two-phase titanium alloys with an alpha phase and a beta phase

Abstract

The invention relates to a method for examining a two-phase titanium alloy with an alpha phase and a beta phase. The method comprises the following steps consisting in: (a) cutting a sample from a part made from the alloy; (b) preparing a region (4) of the cut surface of the sample close to the edge (50) thereof, said edge (50) being shared with the outer surface (1) of the part so that the region (4) can be observed; (c) observing the alpha phase of the region (4) at a magnification of more than 5000x; (d) determining whether or not grains are present in the alpha phase of a first area (11) adjacent to the edge (50) of the sample; and (e) when grains are absent from the alpha phase of the adjacent area (11) but grains (22) are present in the alpha phase outside said adjacent area (11), concluding that the alloy is contaminated by a gas.

Description

technical field [0001] The invention relates to a pollution inspection method of a dual-phase titanium alloy having an α phase and a β phase. Background technique [0002] The alpha phase is a phase present in most titanium (Ti) alloys and corresponds to a close-packed hexagonal lattice of Ti atoms. [0003] Titanium alloys including alpha phase are easily contaminated by other chemical elements with which they come into contact. For example, they are susceptible to contamination by gases such as oxygen, nitrogen, hydrogen and halogen gases. Due to reaction kinetics, this contamination is often visible when substances are exposed to temperatures around 500°C or higher. This contamination causes the exposed surface of the titanium alloy to become brittle, resulting in a deterioration of its mechanical properties. [0004] This is the reason why the heat treatment performed on titanium alloys during the manufacturing process is performed in vacuum, ie exposed to very low co...

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Problems solved by technology

[0010] However, the metallographic technique is sometimes relatively imprecise

Changing the particle size and detecting contamination based solely on visually assessing the contrast between the white border and the adjacent darker gray portion prevents accurate measurement of the thickness of the white border, therefore, the technique does not always give an accurate indication of the extent of the contamination. degree

[0011] Also, this technique is not suitable for certain titanium alloys such as TA5CD4

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