Effects of boron,titanium,and nitrogen on the hardenability of boron-treated steels for heavy machinery

The effects of boron, titanium, and nitrogen contents on the hardenability of boron-bearing steels have been studied. The boron hardenability factor was found to be a rapidly decreasing function of (total N – N as TiN). Thus, it was confirmed that titanium plays a very important role in retaining the excellent hardenability through its scavenging effect for dissolved nitrogen. From the results of this work, a useful guide concerning the limitation of total nitrogen content was derived for the development of titanium-free boron steels characterized by a good combination of hardenability, machinability, and toughness, especially for heat-treated parts made for heavy equipment.