An Investigation on Boron-treated Steels (3rd Report) On the Hardenability of Boron-Treated Medium-Carbon Steels, Especially the Effect of Nitrogen-content in Steels

Dealing boron-treated steels, with the Medium-Carbon (0.3∼0.4%), the maximum hardenability was gained by the addition of an order of about 0.003%B; and with increase of the nitrogen content in steels, the desirable effect of boron on the hardenability decreased sharply, and the effect completely disappeared when the nitrogen content exceeded an order of 0.02%.And when the small amonnt of Al(0.1%) or Ti(0.03%) was added to the steels prior to the addition of boron, the effect of boron usually appeared more sharply, because they acted as the fixers of nitrogen.