Boron Steels

Abstract

A small amount of boron (0'0005 per cent minimum ) is successfully used in the United States as a replacement of appreciable quantities of nickel, chromium and moly-bdenum in structural low-alloy steels. The standard AISI grades are designed to replace conventional alloy steels of equivalent hardenability. The boron steels are norma- lly manufactured by the basic open-hearth process, although the basic electric furnace process is also used . Special equipment is not required in their manufacture and fabrication , but certain precautions are essential in making the boron addition and fini- shing the heats. The production of boron steels attained a maximum of about 0.7 million tons in 1952 and thereaft -er decreased to about 0.5 and 0.25 million tons in 1953 and 1954 respectively. Examples are given to show the general influence of boron on hardenability and mechanical properties of selected steels. A review is made of the literature on the mechanism of boron in increasing hardenability and a summary is presented of known facts on the behaciour of boron in iron and steel.