HARDENING FROG POINTS BY EXPLOSIVE ENERGY,
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
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Experiments were made to determine the most efficient method of strain hardening railroad frog points in order to increase their fatigue resistance. Mechanical strain hardening with rolls 40 mm in diameter under a load of 8 tons produced in standard frogs cast from G13L high-manganese steel AISI Hadfield steel a work-hardened surface layer 3-5 mm thick with a hardness of 340 HB. In other experiments, the frogs were hardened by exploding a plastic high explosive of the L-48 mk type cut to shape from 4.3 mm thick sheet and placed onto the frog point surface. By this method a work-hardened layer 35-40 mm thick with a hardness of 375 HB was obtained. In fatigue tests, done with reciprocal rolling of a wheel 500 mm in diameter under a load of 50 tons, the first visible damage transverse cracks and flaking appeared after 350,000 cycles on explosive-hardened frog points, and after 150,000-200,000 cycles on conventionally work-hardened frog points. A similar increase in the service life of explosive-hardened railroad frogs was also observed under actual operating conditions. Explosive hardening can be recommended for series production of G13L steel frog points.
- Metallurgy and Metallography
- Fabrication Metallurgy