Effect of laser hardening on microstructure and wear resistance in medium carbon/chromium steels
Metallographical (optical, TEM, SEM), spectroscopic, abrasive wear resistance and microhardness investigations of Fe/Cr/Mn/C steels heat treated by a continuous CO/sub 2/ laser are described. Laser hardening resulted in wear resistance of 1.4 to 1.6 times better than that of conventionally hardened steels. Laser melting followed by rapid solidification allows formation of a solidified layer with high wear resistance only when the scanning velocity and mass of the samples were sufficient to realize high cooling rates. The variations in the wear resistance and microhardness with distance from the heated surface were similar. The grain refinement caused by rapid laser-heating and high stresses induced during cooling create essentially fine, highly dislocated lath and internally twinned martensites with some amount of stable, interlath retained austenite. This structure has in turn beneficial effects on wear resistance and toughness. Laser-heat treatment for deep melting of the surface layers of the steels shows only a small improvement in wear resistance. Such heat treatment results in delta ferrite retention (10Cr steel) and chromium segregation to cell boundaries.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5730332
- Report Number(s):
- LBL-21418; CONF-860620-6; ON: DE86012021
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360100* -- Metals & Alloys
ALLOYS
CARBON DIOXIDE LASERS
CARBON STEELS
CHROMIUM ALLOYS
CHROMIUM STEELS
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
GAS LASERS
HARDENING
HARDNESS
HEAT TREATMENTS
HEATING
IRON ALLOYS
IRON BASE ALLOYS
LASER-RADIATION HEATING
LASERS
MECHANICAL PROPERTIES
MICROHARDNESS
MICROSCOPY
MICROSTRUCTURE
PLASMA HEATING
STEELS
WEAR RESISTANCE