Laser cladding as repair technology for Ti–6Al–4V alloy: Influence of building strategy on microstructure and hardness

• Ti–6Al–4V deposits made by laser cladding to simulate repair are investigated.
• Effects of the building strategy and the incident energy on deposits were examined.
• Both the deposit and its HAZ do not mechanically weaken the repaired part.
• A simplified thermo-metallurgical scheme is proposed based on the results.

Laser cladding is a metal deposition technique used to fabricate or repair components made from high value metallic alloys. In the present work Ti–6Al–4V deposits with variable thickness are made to assess the use of laser cladding as a repair technology. Both the effect of the building strategy (BS) and the incident energy (IE) on the metallurgical characteristics of the deposits in relation to their complex thermal history have been studying. It is shown that for the configuration consisting in a decreasing track length (DTL) under high IE, a gradient of cooling rate exists that leads to the presence of different phases within the microstructure. Conversely homogeneous microstructures are present either for the configuration with a constant track length (CTL) under high IE, and for the strategy obtained from a DTL under low IE. Depending on the possible heat accumulation the nature of the phases are determined together with hardness maps within the deposits. Some qualification criteria are set prior to tensile tests to selected adequate candidate-deposit that does not weaken the cladded material when it is stressed. A thermo-metallurgical scheme is proposed that helps in understanding the effect of both the BS and the IE on the microstructure.

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