Residual stress determination from a laser-based curvature measurement
Thermally sprayed coating characteristics and mechanical properties are in part a result of the residual stress developed during the fabrication process. The total stress state in a coating/substrate is comprised of the quench stress and the coefficient of thermal expansion (CTE) mismatch stress. The quench stress is developed when molten particles impact the substrate and rapidly cool and solidify. The CTE mismatch stress results from a large difference in the thermal expansion coefficients of the coating and substrate material. It comes into effect when the substrate/coating combination cools from the equilibrated deposit temperature to room temperature. This paper describes a laser-based technique for measuring the curvature of a coated substrate and the analysis required to determine residual stress from curvature measurements. Quench stresses were determined by heating the specimen back to the deposit temperature thus removing the CTE mismatch stress. By subtracting the quench stress from the total residual stress at room temperature, the CTE mismatch stress was estimated. Residual stress measurements for thick (>1mm) spinel coatings with a Ni-Al bond coat on 304 stainless steel substrates were made. It was determined that a significant portion of the residual stress results from the quenching stress of the bond coat and that the spinel coating produces a larger CTE mismatch stress than quench stress.
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC07-99ID13727
- OSTI ID:
- 758128
- Report Number(s):
- INEEL/CON-99-01176; TRN: AH200021%%177
- Resource Relation:
- Conference: International Thermal Spray Conference (ITSC-2000), Montreal, Quebec (CA), 05/08/2000--05/11/2000; Other Information: PBD: 8 May 2000
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SPRAYED COATINGS
RESIDUAL STRESSES
SUBSTRATES
THERMAL EXPANSION
QUENCHING
DIAGNOSTIC TECHNIQUES
NICKEL
ALUMINIUM
STAINLESS STEEL-304
SPINELS
SPRAYED COATING
MECHANICAL PROPERTIES
RESIDUAL STRESS
COEFFICIENT OF THERMAL EXPANSION (CTE) MISMATCH STRESS
MOLTEN PARTICLES
CURVATURE
COATED SUBSTRATE
QUENCHING STRESS
SPINEL COATING