The influence of the nitrogen (0.04-0.16%), degree of working (0-30%), and the solution-treatment temperature (1200°, 1250°C) on the high-temperature age-hardening of Timken 16-25-6 heat-resisting alloy were studied.
The results were summarized as follows.
(1) The hardness increased almost linearly by the cold working (0-30%) but had little difference by the nitrogen content.
(2) The age-hardening at 600°C was not nearly influenced by the nitrogen content and the effect of the degree of working was somewhat greater than the effect of the solution-treatment temperature.
In the case of aging at 700°C, the increase of hardness was remakable and the solution- treatment temperature was effective much greater than the degree of worklng, and the higher the solution-treatment temperature was, the more became the increase of hardness.
On the contrary the higher the nitrogen content was, the smaller became the increase of hardness. The increase of hardness at 800°C was smaller than that at 700°C and the influence of nitrogen at 800°C was similar to that at 700°C.
(3) In regard to the influence of the degree of workeing on the increase of hardness, in the case of aging at 600°C, the increase of hardness decreased little according to increase of working, and in the case of aging at 700°C the maximum increase was obtained by the working at 5-10%.
In the case of aging at 800°C, the increase of hardness decreased linearly according to increase of working and at the degree of working above 20% softening arose.
(4) In the microstructure, the working accelerated the precipitation and the precipitate reaction became 4-5 times by the 5% working. The greater the degree of working was, the more became the quantity of precipitates, and the more homogenious the distribution of precipitates.
Generally the smaller the nitrogen coatent was, the faster became the coagulation of the precipitated particles.
(5) In the tempering at 500-1100°C of cold worked (0-50%) materials, the more the degree of working was, the lower became the temperature at which the maximum hardness obtained. In the case of tempering at 500-1100°C of 26% cold worked materials, the higher the nitrogen content was, the slower became the decrease of hardness.