There is a phenomenon that the fatigue strength of notched steel treated by low temperature gas carbonitriding gets lower than those treated by tufftriding when the stress concentration coefficient is large.
In order to improve this demerit so that this point of the former treatment can be raised up to the degree of that of the latter treatment an investigation was made about the influence of gas flow amount, gas mixture ratio and treatment temperature upon the compound layer and form of diffusion zone.
And under the optimum conditions obtained from this investigation the above written problem was resolved.
