Kohsuke Horikawa

Characteristics of residual stress generated by MoSi2 plasma thermal spraying

Summary This paper describes an investigation of plasma thermal spraying of MoSi2 offering a high melting point together with excellent high-temperature oxidation resistance. MoSi2 powder was deposited by low-pressure plasma thermal spraying on the surfaces of blasted SS400 substrate specimens precoated with 50%Ni-50%Cr. The residual stress generated in the specimens was then determined. Compressive stress is generated in the MoSi2 sprayed deposit. Tensile stress is generated in the 50%Ni-50%Cr sprayed deposit except at the SS400 substrate surface. A series of experiments was conducted to clarify the validity of the residual stress distribution obtained. These results suggest the following: When only blasting treatment is performed, compressive stress is generated from the upper surface to 0.3 mm inside. Minor tensile stress is also generated inside. When 50%Ni-50%Cr is deposited after blasting treatment, the residual stress is tensile in the 50%Ni-50%Cr layer and compressive on the substrate upper surfac...

4.4 – Estimation of the Applicability of Thin Steel Plate as Sacrificial Test Piece

Thin steel plates, which have initial cracks at the center, are used as the Sacrificial Test Pieces in this study. “The Sacrificial Test Piece” is attached to the member of a main structure in order to evaluate the damage before the appearance of a crack in the member of the main structure. The purpose is to show the practical applicability of “the thin steel plate with crack as the Sacrificial Test Piece” for monitoring the fatigue damage parameters on bridge members. In this research, it is decided that the applicable range of crack length and the crack propagation properties of the Sacrificial Test Pieces to evaluate the fatigue damage parameter are obtained. And it is suggested that the fatigue damage parameter can be estimated by the Sacrificial Test Pieces with practical accuracy by the test under constant amplitude loading.