Tensile properties of HVOF sprayed Inconel 625 coatings subjected aqueous corrosion

Abstract

PurposeTo examine the tensile properties of high velocity oxy‐fuel (HVOF) sprayed Inconel 625 coating of steel substrate before and after the aqueous corrosion.Design/methodology/approachWorkpieces were cut from steel sheets. After chemical and ultrasonic cleaning, workpiece surfaces were sand blasted and HVOF sprayed Inconel 625 coated. The coated and un‐coated surfaces were subjected to the aqueous corrosion tests for one and three weeks. After the completion of the corrosion tests, tensile properties of the workpieces were examined.FindingsThe workpieces subjected to a three weeks static corrosion environment fail at a lower load than the untreated workpiece due to high stiffness. The defect sites in the coating and at the interface act as stress risers and contribute substantially crack initiation and propagation in the coating. Under increasing tensile load in the plastic region, the substrate material can no longer support the coating. This results in extended cracking and gradually spalling of the coat. When the local critical stress for crack propagation is reached, elongated cracks occur, which in turn initiates splitting separation between the adjacent zones in the coating. The shear deformation of the adjusted zones results in the total failures of the coating.Research limitations/implicationsThe tests can be extended to include the duplex treated workpieces such as the laser treatment of surface after HVOF sprayed coating. This enhances the bonding of the coating through thermal integration of the coating and the base substrate material.Practical implicationsThe results can be used to assess the HVOF sprayed coatings.Originality/valueThis paper provides information on mechanical behavior of HVOF sprayed coating when subjected to the tensile force and offers practical help for the researchers and scientists working in the coating area.

Young's modulus measurement and study of the relationship between mechanical properties and microstructure of air plasma sprayed alloy 625

“…Previous reports concerning the microstructure of HVOF deposited alloy 625 coatings have appeared in the literature [5,6]. Some investigation reported the effect of HVOF deposited alloy 625 on mechanical properties of steel plates [7,8]. Although coatings produced by VPS have better quality compared to the APS one (higher density, stronger splat adhesion, etc) but it is relatively more expensive and complicated technique with less flexibility.…”

Pulsed plasma nitriding of high velocity oxy-fuel sprayed Inconel 625 coatings

“…Due to the severe impact of particles sprayed under a condition of high velocity and low temperature, high velocity oxy-fuel (HVOF) coatings offer low porosity, low surface roughness, high bonding strength and high hardness compare to other coating technique. [5][6][7][8] Chen et al (2019) studied the tribological behavior of various Inconel 625 coatings obtained through flame spraying (F), arc spraying (A), plasma spraying (P), or HVOF spraying (H) in a saline solution and deionized water. Their results indicate that the corrosion-wear resistance of the Inconel 625 coatings was in the order F > A>P > H due to the high oxide content within its coating layer as an antiwear phase for tribocorrosion protection.…”