The stress restored in steels (0.6, 0.9% plain carbon and 0.3_??_0.9%, C, 3% Ni steels) variously heat-treated has been measured, the dimension of the specimen is 4mm×9mm×100mm. Some quenched specimens consisted of a single structure and some were heterogeneous. In the case of a single structure, the stress-depth curve was always simple and had no maximum or minimum point while in the case of heterogeneous structure the curve had a minimum point, generally. In all cases of the single structure, the stress was maximum at the surface and was always in tension. In the case of all martensitic structure, the maximum stress at the surface was not larger as the content of the carbon increased. In the case of the stepped quenching, the stress increases as the temperature of the second quenching elevates from Ar'' point and attains a maximum and then decreases. The stress at the surface of the quenched specimen whose structure is uniform were as follows. martensite>troostite>sorbite>pearlite
In the case of austempering above 480°, the residual stress was very small.
(Received 1948/11/18 Published 1949/06/20)
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