Alloy steel has been a hundred years of history. Industrial use of alloy steel is mostly in the second half of the 19th century. At that time, due to the increasing production and use of steel, the machinery manufacturing industry needed to solve the steel cutting problem. In 1868, the British man Maite (RFMushet) invented the composition of 2.5% Mn-7% W self- Increase the cutting speed to 5 m / min. With the development of commerce and transport, in 1870 in the United States with chrome steel (1.5 ~ 2.0% Cr) in the Mississippi River built a span of 158.5 meters bridge; due to difficulties in processing components, later, some industrial countries to nickel Steel (3.5% Ni) builds large span bridges. At the same time, some countries will also use nickel steel for the construction of warships. With the development of engineering technology, requiring the speed of rotation of machinery, 1901 appeared in Western Europe, high-carbon chromium rolling bearing steel. 1910 and the development of the 18W-4Cr-1V-type high-speed tool steel, and further increase the cutting speed to 30 m / min. It can be seen that the advent and development of alloy steel is adapted to the requirements of the development of social productive forces, especially inseparable from the needs of machinery manufacturing, transportation and military industry.