<P> In 1868 the English metallurgist Robert Forester Mushet developed Mushet steel , considered to be the forerunner of modern high speed steels . It consisted of 2 % carbon ( C ) , 2.5 % manganese ( Mn ) , and 7 % tungsten ( W ) . The major advantage of this steel was that it hardened when air cooled from a temperature at which most steels had to be quenched for hardening . Over the next 30 years the most significant change was the replacement of manganese ( Mn ) with chromium ( Cr ) . </P>
<P> In 1868 the English metallurgist Robert Forester Mushet developed Mushet steel , considered to be the forerunner of modern high speed steels . It consisted of 2 % carbon ( C ) , 2.5 % manganese ( Mn ) , and 7 % tungsten ( W ) . The major advantage of this steel was that it hardened when air cooled from a temperature at which most steels had to be quenched for hardening . Over the next 30 years the most significant change was the replacement of manganese ( Mn ) with chromium ( Cr ) . </P>
the percentage of carbon in high speed steel is
the percentage of carbon in high speed steel is
2 %
2 %