Tensile and fatigue strength of SUS304 stainless steel repaired by a high velocity oxy-fuel thermal spraying

Abstract

Tensile and fatigue tests were conducted on type 304 stainless steel plate-shaped specimens repaired by High Velocity Oxy Fuel (HVOF) spraying. Specimen surfaces were machined for repair into trapezoid with the same depth, the same length, and various slope angles (called here cutting angles). During tensile tests, damage evolution in the repaired part was continuously monitored under increasing load. Quantitative evaluation of the relationship between the strain gauge attached to the repaired part surface and the cross-head displacement was performed. In fatigue tests, influence of the repaired shape on damage evolution was studied, and obtained fatigue lives were compared between the cutting angles. According to tensile testing results, crack initiation strain values increase with cutting angles. At the same time, residual stresses were mostly compressive and almost independent from cutting angles, thus positively affecting the magnitude of fatigue strength. Fatigue test results indicated that specimens repaired with a cutting angle of 50°possess a superior fatigue life. The results showed that the HVOF spraying can potentially replace welding repair.

Keywords

• thermal spraying
• hvof
• repairing
• conicraly
• tensile strength
• crack initiation
• fatigue life