Warm spray applied to steel component repair: experimental study

Abstract

Experimental investigations were carried out in order to evaluate the possibility of using warm spray as a repair technique for steel components. A high velocity oxygen fuel system was modified to deposit an AISI 316 stainless steel feedstock powder in solid state. A preliminary study was carried out on the spray conditions to optimise the deposition process. The powder was deposited on a steel sample, and the quality of the coating was evaluated by optical microscope observations: a limited porosity was observed in the repair. Test damage was produced in another steel sample and was repaired by warm spray. Residual stresses and microhardness of the repaired area were measured. It was found that beneficial compressive residual stresses were produced in the repaired area, which also exhibits a good microhardness, slightly higher than that of the substrate. Finally, adhesion tests were carried out, and a strength >46 MPa was found.

Keywords:

• Warm spray
• Repair
• Residual stresses
• Microhardness
• Adhesion strength

Acknowledgements

The authors wish to thank Mrs V. Ferrari for her collaboration in carrying out the adhesion tests.