Investigation and analysis of material 65Mn
65Mn steel has the advantages of high hardness, good hardenability, low decarburization tendency, low price, good machinability, etc., but it is sensitive to overheating, is prone to quenching cracks, and has temper brittleness. 65Mn steel is widely used. Mainly produced into steel wire, steel belt, used to manufacture various flat and round springs, leaf springs and spring sheets with less cross-section. 65Mn steel is widely used in the automobile industry, electronics industry, trains and other transportation vehicles. It can manufacture circular saw blades for high-speed cutting of various types of steel, steel pipes and steel bars.
Brand, composition, organization, heat treatment, performance, use introduction
Material designation: 65Mn American ASTM: 1566, SEA: 1566 (1066) Former Soviet Union ГОСТ: 65Г
(The steel composition is C=0.64%, Mn=0.92%, Si=0.18%, S=0.005%, P=0.017%. The degree of crystallinity is 4 to 8. The austenitizing temperature is 830℃)
65Mn steel is generally used after quenching and tempering. When tempered below 450℃, it is tempered martensite, and when tempered above 450℃ it is tempered sorbite.
Heat treatment process:
Surface treatment process: using surface sandblasting treatment. 65mn steel circular saw blade is carbonitrided in advance to increase the carbon and nitrogen content, and then conventional heat treatment is performed to improve the tempering stability of the tooth, thereby increasing the hardness and wear resistance of the tooth, and improving the circular saw blade Life.
Heat treatment process parameters
Annealing Normalizing Temper Tempering Quenching Tempering Stress Relief Tempering (cold drawn spring steel wire)
810 810 680～700 810 360～570 250～360
Cooling test Furnace cooling Air cooling Air cooling Oil/water cooling Air cooling Air cooling
Density ρ=7.81 g/cm3
Welding performance: poor
Use of the material: The steel can be cold rolled into steel plates, steel strips and steel wires to make springs. 65Mn can also be made into tools such as fitter’s chisel and scribing needle. 65Mn steel can be used to make small springs with a general section size of about 8-15mm, such as various small flat and round springs, bottom springs, spring springs, and also suitable for making spring rings, valve springs, clutch springs, brake springs, etc. . 65Mnj is one of the materials used to make various leaf springs and wire springs. It is used in vehicles, trams, trains and other transportation vehicles. It is also widely used in the manufacture of meters, furniture, and children’s toys.
Influence of Mn:
It is generally believed that manganese is a beneficial element in steel. In 65Mn, most of manganese is dissolved in ferrite to form a replacement solid solution and strengthen ferrite. A part of manganese is also dissolved in Fe3C to form alloy cementite. Manganese can also increase the relative amount of pearlite and make It becomes thinner, thereby increasing the strength of the steel. Manganese can be combined with S to form MnS to reduce the harmful effects of S.