Metal treatment – Compositions – Heat treating
Patent
1983-01-10
1985-01-22
O'Keefe, Veronica
Metal treatment
Compositions
Heat treating
148 39, 138143, B32B 1500
Patent
active
044950039
ABSTRACT:
A steel tube having a small outside diameter and a large wall thickness, for use, for example, as a high pressure fuel injection pipe for a diesel engine, has a hardened layer on at least its internal surface. The hardened layer is formed by a diffusion layer which comprises a solid solution of nitrogen formed by tufftriding, and which is completely free from any intermetallic compounds, i.e. Fe.sub.3 N and Fe.sub.4 N. A method of manufacturing such a tube is also disclosed, and comprises tufftriding a steel tube in a molten bath of sodium cyanide while it is being axially vibrated, to form the diffusion layer, and heat treating the tube in a gaseous atmosphere to decompose any intermetallic compound on the diffusion layer.
REFERENCES:
patent: 2541116 (1951-02-01), Somes
patent: 3208885 (1965-09-01), Muller
patent: 4261769 (1981-04-01), Usni
patent: 4346739 (1982-08-01), Asada
Metals Handbook, vol. 2, 8th Ed., Amer. Soc. Metals, Metals Park, Oh., pp. 146-151, 1974.
Frank Smith, Metals (Australia) Tufftride-Its Metallurgy Application and Evaluation, pp. 147-152, Jun. 1970.
SAE Testing Stands for Diesel Fuel Injection Systems-SAE J970a pp. 24,104-24,109 and SAE J521b-Fuel Injection Tubing Connections.
Casella Anthony J.
Hespos Gerald E.
O'Keefe Veronica
Usui Kokusai Sangyo Kabushiki Kaisha
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