1>.Classification and Introduction of
1, the source of
The 1882 first austenite , the 1883 British Hadfield (R.A.Hadfield) patent high manganese steel. High manganese steel can be divided into two categories according to their different purposes:
2, wear-resistant steel
Kind of steel of 10% to 15% manganese, high carbon content, is generally from 0.90% to 1.50%, most more than 1.0%. Its chemical composition (%):
C0.90 ~ 1.50Mn10.0 ~ 15.0
Si0.30 ~ 1.0 S ≤ 0.05 P ≤ 0.10 such the largest amount of high manganese steel, commonly used to make the excavator shovel teeth, mill wall and broken wall of the cone crusher, fork plate mill liner , railway rut fork, plate hammer, hammer.
The ingredients of high manganese steel cast structure is usually composed of austenite, carbides and pearlite, sometimes also contain small amounts of phosphorus eutectic. Carbide a long time, often in the grain boundary reticular. High manganese steel cast structure is very brittle, and can not be used, the need for the solution treatment. Heat treatment method commonly used is the solution treatment, upcoming steel heated to 1050 to 1100 ° C, and insulation to eliminate the cast structure, single-phase austenite, and then water quenching, such organizations to maintain room temperature. The heat-treated steel, strength, ductility and toughness are increased greatly, so such a heat treatment method is often called water toughening treatment. Mechanical properties after heat treatment: σb615 ~ 1275MPa σs340 ~ 470MPa ζ15% ~ 85% ψ15% ~ 45% aKl96 ~ 294J/cm2 HBl80 ~ 225
High manganese steel, there will be a small amount of carbides undissolved after solution treatment, even when its small number of meet inspection standards.
The metal surface is plastically deformed by the impact load, and the austenite structure of high manganese. Deformation strengthening results in the deformable layer within the hardening phenomenon, the surface hardness is greatly improved. Low-impact load can reach HB300 ~ 400, high impact load, can be reached HB500 to 800. With the different impact load, surface hardening layer depth of up to 10 ~ 20mm. The high hardness of the hardened layer can resist impact abrasive wear. High manganese steel strong impact abrasive wear conditions, excellent resistance to wear, Guchang used in mining, building materials, thermal power, machinery and equipment, making wearable pieces. Little effect of work hardening in the working conditions of the low-impact, high manganese steel can not play to the characteristics of the material.
High manganese steel grades and Scope: ZGMn13-1 (C 1.10% ~ 1.50%) for low-impact pieces, ZGMn13-2 (C1.00% ~ 1.40%) for ordinary pieces, ZGMn13- 3 (C0.90% ~ 1.30%) for complex parts, ZGMn13-4 (C0.90% ~ 1.20%) for high impact pieces. Manganese content of these four kinds of grades of steel are 11.0% and 14.0%.
Cold deformation during the impact loads due to the large increase in dislocation density, the dislocation of the settlement, the interaction of dislocation pileup and dislocations and solute atoms of the steel be strengthened. This is an important cause of work hardening. Another important reason is the high manganese austenitic stacking fault energy is low, deformation stacking fault prone, and thus create the conditions for the the ε martensite formation and the generation of deformation twins. Deformation hardening layer of conventional high manganese steel components often can see the high density of dislocations, dislocation pile and tangles. ε martensite and deformation twins appear difficult to deformation of the steel, especially the latter role. The above factors are enhanced by the high degree of the high manganese steel hardened layer, a substantial increase in hardness.
High work hardening manganese steel easily, making it difficult to process, the vast majority of castings, a very small amount of forging processing. The better performance of high manganese steel casting. The low melting point of steel (about 1400 ° C), the liquid steel, the solidus temperature interval smaller (approximately 50 ° C), low thermal conductivity of steel, therefore, the fluidity of molten steel, easy pouring molding. The linear expansion coefficient as pure iron of 1.5 times to 2 times the carbon steel, the volume shrinkage when casting and linear shrinkage rate of high manganese steel, prone to stress and crack.
To improve the performance of high manganese steel alloying, micro-alloyed carbon manganese content adjustment and precipitation strengthening treatment, and has been applied in the production practice. The emergence of metastable austenitic manganese can be compared with Bureau gao significantly reduce the carbon steel, manganese content and Deformation strengthening faster, be applied to the working conditions of high and low-impact load, which is a high manganese Steel’s new development.
3, no magnet
Manganese of the kind of steel is greater than 17%, the carbon content is generally 1.0% or less, often in the motor industry for the production of the grommet. The type of steel density of 7.87 ~ 7.98g/cm3. Carbon, high manganese content, the poor thermal conductivity of steel. The thermal conductivity coefficient of 12.979W / (m · ℃), approximately 1/3 of the carbon steel. Because steel is austenite structure, non-magnetic, the magnetic permeability μ as 1.003 to 1.03 (H / m).
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