• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.918-928
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• 1995

This paper deals with the various mechanical properties and fatigue strength in the FRW1 (friction welded interface) of high speed steel (HSS-Co) to SM55C through the tensile test, hardness test and fatigue test. The data of FRW specimens are also compared with those of the base materials (HSS-Co and SM55C steel). Three kinds of specimens used in this study are the friction welded joints, HSS-Co and SM55C carbon steel with circumferential notch, saw notch and smooth, respectively. It is confirmed that the applied welding conditions are optimum methods in order to minimize the heat affected zone (HAZ) and hardness distribution at the HAZ. The fatigue strengths at N = 10$^{6}$ cycles of smooth, circumferential notch and saw notch specimens in the FRW joints are about 299.2 MPa, 123.8 MPa and 247.5 MPA, respectively. The fatigue strength of the friction welded joints is almost equal to that of the SM55C carbon steel in the optimum welding conditions. The fatigue cracks initiated at the welded zone are propagated along the side of SM55C steel.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.4
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• pp.929-940
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• 1995

The fatigue strength and fracture topography in the friction welded interface of high speed steel (HSS-Co) to SM55C carbon steel have been investigated through the fatigue test, SEM fractograph and EDS (energy dispersive spectrometer) analysis. Three kinds of specimens used in this research are the friction welded joints, HSS-Co and SM55C carbon steel with circumferential notch, saw notch and smooth, respectively. The notch sensitivity factor, .eta. of the friction welded joints is lower than that of the base materials, and that represents a superiority of the joint performance of FRW. Fracture topography of the FRW specimens with a notch showed a cleavage or brittle appearance, while that of the FRW smooth specimen appeared to be ductile. Furthermore, although fatigue crack likely initiated near the weld interface of the FRW smooth specimen, crack propagation continued into the HAZ of SM55C steel. Finally, fatigue fractures of the base materials were associated primarily with the inclusions located at the outer periphery of the specimen.