Representation of high-quality carbon structural steel 
 ① Steel beginning of the two numbers indicate the carbon content of steel, the average carbon content of the very few that, for example, the average carbon content of 0.45 percent of steel, steel number "45", it is not a sequence number, it can not be read as 45 steel. 
 ② high quality carbon manganese structural steel, manganese should be marked, such as 50Mn. 

 2.65Mn Steel Properties and Applications 
 65Mn high-carbon steel, spring steel. 
 1.) 65Mn standard content: carbon 0.62 manganese 0.70 silicon 0.17 to 0.37 0.50 to 0.80 Phosphorus 0.035 Sulfur 0.035 Chromium 0.25 Nickel 0.25. 
 2.) 65mn hardness: 65Mn steel is generally more isothermal hardening, etc. There are two levels of temperature and hardness :40-45HRC, and 43-50HRC, the former suitable for spring and other parts of large deformation, which applies a thick spine claw, grasp the card like a small deformed parts. Small parts with salt bath furnace with heating, fast oil quenching, the hardness can reach 55 - 62HRC. 
 3.) 65Mn steels: 65Mn steel with high hardness, good hardenability, less tendency to decarburization, low prices, cutting and good, but it has overheated sensitivity, easy to produce quenching cracks, and tempering brittle, 65Mn steel widely used, the main production into steel wire, steel, used in the manufacture of various cross-section less flat, round spring, spring, and spring and so on. 65Mn steel in the automotive industry, electronics industry, trains and other means of transport a great amount. It can produce saw blades for cutting various types of high speed steel, steel pipes and steel bars. 
 Corresponding foreign material grades: 65Mn U.S. ASTM: 1566, SEA: 1566 (1066) the former Soviet Union ГОСТ: 65Г. 

 3. Common manganese steel 
 16Mn, 65Mn steel. 
 Application: 16Mn used in wear resistant lining and fan blades, etc. 
 65Mn used bucket elevator hopper scraper, etc.