Study of dilution in laser cladding of a carbon steel substrate with Co alloy powders

Abstract

High power diode laser with coaxial powder injection was used to deposit single tracks of cobalt alloy on to a carbon steel plate in order to study dilution. Two different methods to evaluate dilution are proposed and validated: dilution results to be proportional to the average percent or iron present in the clad. To study the correlations between dilution and processing parameters, clads were produced in different processing conditions. Dilution is correlated with the specific energy, and equation to estimate the average iron contamination of the clads was found. ‘Trial and error’ method was applied to improve this estimation. A statistically better prediction of the iron contamination is obtained when the combined parameter P^2.5/F⁴ is used. Dilution influences clad microstructure and thus hardness of the final coating, which decreases on increasing dilution. Phase distribution is also affected by dilution, Fe and C contamination stabilises α-fcc phase.

Keywords:

• Laser cladding
• Dilution
• Iron contamination
• Combined parameters
• Processing parameters
• Specific energy