SEDL / STP / STP1327-EB / STP12146S

Laser Glazed Bearings

Hetzner, DW
Research Specialist, The Timken Company, Canton, OH

Pages: 25    Published: Jan 1998

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Abstract

In the past decade high power, reliable, carbon dioxide lasers have become commercially available. Laser glazing is a process in which a focused laser beam is used to melt a very small portion of a component. As the beam moves away from the melted region, the underlying mass of the component causes the liquid pool to rapidly solidify. A major advantage of laser glazing is that the refined structure is only created in areas where high load carrying capacity is required

Initially rods manufactured from BG 42 and M 50 steels were laser glazed. Laser glazing transformed the normal, fine grain, martensitic steel matrix into a very fine dendritic microstructure. The carbides in the laser glazed material were greatly reduced in size due to very rapid solidification. Using a standard ball / rod rolling contact fatigue tester, enhanced rolling contact fatigue life was realized from the laser glazing process.

LM 12749 tapered roller bearing cones were fabricated from M 50 high speed steel and laser glazed. At 200% catalog load, the L^15.9% life of the laser glazed M 50 bearings was 370% greater than the wrought cones. Similarly, when tested at 300% catalog load, the laser glazed bearings had L^15.9% life 580% greater than the wrought cones.

Laser processing has been applied to 440 C stainless steel. In this alloy similar reduction in the size and distribution of large chromium carbides was achieved. The glazed 440 C was approximately 20 Knoop hardness points higher than the wrought alloy. Examples and properties of glazed microstructures in ball bearings and other alloy systems are discussed.