The production development of alloy steel

second half. At that time, due to the increasing production  use of steel, the machinery manufacturing industry needed to solve the processing  cutting problem of steel. In 1868, the British R.F.Mushet invented a self-hardening steel with a composition of 2.5%Mn-7%W. Increase the cutting speed to 5 m/min. With the development of commerce  transportation, a bridge with a span of 158.5 meters was built over the Mississippi River with chromium steel (1.5-2.0% Cr) in the United States in 1870; due to difficulties in processing the components, later, some industrial countries switched to nickel Steel (3.5%Ni) to build long-span bridges. At the same time, some countries also use nickel steel to build warships. With the development of engineering technology, it is required to speed up the rotation speed of machinery. In 1901, high carbon chromium rolling bearing steel appeared in Western Europe. In 1910, 18W-4Cr-1V high-speed tool steel was developed, which further increased the cutting speed to 30 m/min. It can be seen that the advent  development of alloy steel is inseparable  the requirements of the development of social productive forces, especially the needs of machinery manufacturing, transportation  military industries.

After the 1920s, the electric arc furnace steelmaking method was popularized  used, which created favorable conditions for the mass production of alloy steel. The development of chemical industry  power industry has promoted the expansion of alloy steel varieties, so stainless steel  heat-resistant steel came out during this period. In 1920, the German E. Maurer invented the 18-8 stainless acid-resistant steel. In 1929, Fe-Cr-Al resistance wire appeared in the United States. By 1939, Germany began to use austenitic resistance in the power industry. hot steel. After the Second World War to the 1960s, it was mainly the era of the development of high-strength steel  ultra-high-strength steel. Due to the needs of the aviation industry  the development of rocket technology, many new types of high-strength steel  ultra-high-strength steel appeared, such as precipitation. Hardened high-strength stainless steel  various low-alloy high-strength steels are its representative steel grades. After the 1960s, many new metallurgical technologies, especially the out-of-furnace refining technology, were widely adopted,  alloy steel began to develop in the direction of high purity, high precision  ultra-low carbon,  maraging steel  ultra-pure ferrite appeared. Stainless steel  other new steel grades. There are thousands of alloy steel grades  tens of thousands of specifications used internationally. The output of alloy steel accounts for about 10% of the total steel output. It is an important metal material widely used in national economic construction  national defense construction.