Steel 30G2, 28Mn6, 30Mn5 - characteristics and application
Manganese structural steel for thermal improvement with low hardenability, relatively good strength properties and high ductility and abrasion resistance. It achieves the best durability at dimensions up to approx. 40mm after hardening in water, in the case of oil hardening the best durability results in dimensions up to approx. 25mm.
30G2 steel is used for heavily loaded parts which must exhibit considerable ductility, flexural strength, torsional strength and resistance to varying torsion and bending. For smaller component, it can be used instead of more expensive substitutes with molybdenum in the chemical composition. Unfortunately, due to the high content of manganese it is prone to tenderness of tempering and coarseness.
Manganese steel is normally used in the heat-treated state, but for forgings optionally the products can be used in normalized condition - especially for large-sized forged products. Steel 30G2 and its equivalents are used on axles, shafts, wheels, cams, engine connecting rods, steam wires, aerospace parts, cams, screws, high pressure cylinders, rotors, drums, stirrers, shanks, forks, crankshafts, crankshafts, levers, and other structural parts after thermal improvement. 30G2 steel is one of low weldability grades.
Mechanical properties of 30G2, 30Mn5, 28Mn6 steel
- Tensile strength Rm > 780 MPa
- Yield point Re > 540 MPa
- Elongation A > 14%
- Contraction Z > 50%
- Notch toughness KU2 > 64 J
- Hardness in softened state < 207 HB
- Density 7,85 g/cm3
Mechanical properties depending on the dimensions
- Tensile strength Rm
- dimensions <16mm = 780 - 930 MPa
- dimensions 16 - 40mm = 780 - 930 MPa
- dimensions 40 - 100mm = 690 - 830 MPa
- dimensions 100 - 160mm = 640 - 780 MPa
- dimensions 160 - 250mm = 590 - 740 MPa
- Tield point Re
- dimensions <16mm = > 590 MPa
- dimensions 16 - 40mm = > 540 MPa
- dimensions 40 - 100mm = > 440 MPa
- dimensions 100 - 160mm = > 440 MPa
- dimensions 160 - 250mm = > 390 MPa
- Contraction, Z
- dimensions <16mm = > 45%
- dimensions 16 - 40mm = > 45%
- dimensions 40 - 100mm = > 50%
- dimensions 100 - 160mm = > 55%
- dimensions 160 - 250mm = > 55%
- Elongation A
- dimensions <16mm = > 14%
- dimensions 16 - 40mm = > 14%
- dimensions 40 - 100mm = > 15%
- dimensions 100 - 160mm = > 15%
- dimensions 160 - 250mm = > 16%
Heat treatment - processes, temperatures and cooling
- Softening at temperatures between 650 - 700°C with slow cooling
- Normalizing at 850 - 880℃
- Hardening with cooling in water at the temperature of 820 - 840 ℃
- Hardening with cooling in oil at the temperature of 830 - 850 ℃
- Tempering with cooling in air at the temperature of 660 - 680 ℃
- Tempering with cooling in water or oil at 540 - 680°C
Mechanical Properties
- Quantity
- Value
- Unit
- Young's modulus
- Tensile strength
- Elongation
- Fatigue
- Yield strength
- 200000 - 200000
- 650 - 880
- 8 - 25
- 275 - 275
- 350 - 550
- MPa
- MPa
- %
- MPa
- MPa
Physical Properties
- Quantity
- Value
- Unit
- Thermal expansion
- Thermal conductivity
- Specific heat
- Melting temperature
- Density
- Resistivity
- 10 - 10
- 25 - 25
- 460 - 460
- 1450 - 1510
- 7700 - 7700
- 0.55 - 0.55
- e-6/K
- W/m.K
- J/kg.K
- °C
- kg/m3
- Ohm.mm2/m
Heat Treatment:
Annealing
Quenching
Tempering
Normalizing
Q & T
√
√
√
√
√
Can produce 30Mn5 specifications and size
- Steel grade
- Specification
- 30Mn5
- 30Mn5
- 30Mn5
- 30Mn5
- 30Mn5
- 30Mn5
Welding and cutting of 28Mn6, 30Mn5 steel
30G2 steel is one of the grades where welding is usually not performed. In exceptional cases, the steel is welded in softened state prior to preheating the product to the temperature of 200-450 ℃. With dimensions below 15mm, the steel needs to be heated to a temperature of 200-330 ℃. For 15 - 25mm dimensions the required temperatures are 250 - 430 ℃. Elements with 25 - 50mm dimensions require a much higher temperature - 300 - 450 ℃.
Steel is welded by electric-arc welding or CO2 welding When cutting components, use an oxyacetylene blowpipe, propane-butane-oxygen or plasma torch. As in the case of welding, 30G2 materials require preheating to 250-300 ℃ before cutting and cooling in the air at the end of the process.
Other indications and equivalents of 30G2 steel:
28MN6, 28 MN 6, 1.1170, 30MN5, 30 MN 5, 1.1165, T 30MN14R, T30MN14R, SAE 1330, UNS G1330, UNS H1330, S MN 433, SMN433, 30Г2, 30Г, 30ГСЛ, ČSN 13141, ČSN 13 141, 20 M 5, 20M5, BS A5, BS A6, 28MN6H, 28MN6HH, 28MN6HL, AM 30 MN 5, F-120 D, UNS H13304, ETG 25, C3135, C3139, 30MNB5, 30 MNB 5, 1.5531, 30MNB4, 30 MNB 4, 1.5526.
TYPICAL APPLICATIONSAlloy structural steels are widely used in the filed of ship, vehicle, airplane, guided missile, weapons, railway, bridges, pressure vessel, machine tools, mechanical components with a bigger sectional size and so on.Mechanical gears, gear shaft, main axis, valve rodMechanical parts - connecting rod, bolt and nutMultidiameter shaftPressure vessel, seamless pipe
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