ABSTRACT: Forging steel can be divided into carbon steel, low alloy steel, medium alloy steel and high alloy steel. Different steels have different properties and uses. Such as 5CrMnMo, 3Cr2W8V steel used in the manufacture of hot forging dies; 1Cr13, 2Cr13, 3Cr13, 4Cr13 steel used in medical tools; 1Cr18Ni9, 1Cr18Ni9Ti steel used in corrosion-resistant parts; Mn13 steel used in wear-resistant parts; used in high temperature 5CrMo, 4Cr10Si2Mo steel for parts; or 304, 304L, 316, 316L, 2205, 45, 42CrMo, 27SiMn, 40CrNiMo, 40Cr, Q345B/C/D/E, GCr15 steel, etc. for cylinder forgings; or for gear forgings 40Cr, 42CrMo, 20CrMnMo, 20CrMnTi, 42CrMo, 40Cr steel and so on.
Here is an excerpt from several common forging steels for a simple analysis. See below:
1. 20SiMn
- It has certain strength and toughness, good machining performance, and good welding performance. Can replace 27SiMn and S45C steel;
- Suitable for electroslag welding, single hydraulic props and parts with large section wall thickness;
- Tensile strength ≥ 450; Yield strength ≥ 255; Elongation ≥ 14; Impact energy ≥ 39; Section size (diameter or thickness): 600~900mm;
- Common heat treatment methods: normalizing + tempering.
2. 35SiMn
- It has high strength, wear resistance, toughness and fatigue resistance, good machinability, good hardenability, poor welding performance, and medium cold deformation plasticity. Good economy, it can completely replace 40Cr or partly replace 40CrNi steel;
- Generally used in various small and medium-sized shafts and gears, such as transmission gears, main shafts, spindles, rotating shafts, connecting rods, worms, tram shafts, generator shafts, crankshafts, flywheels, hubs, impellers, shovel handles, plow shafts, Thin-walled seamless steel pipe. Various important fasteners and large and small forgings;
- Tensile strength ≥885MPa; Yield strength ≥735MPa; Elongation ≥15; Impact energy ≥47;
- Common heat treatment methods: quenching 900 degrees, water cooling, tempering 570 degrees, water cooling or oil cooling.
3. 50SiMn
- High strength and good toughness, good corrosion resistance, high temperature oxidation resistance, easy plastic processing, high surface finish, and sensitivity to temper brittleness. Can replace 40Cr;
- It is mostly used for large ring gears, wheels and shaft parts with small and medium cross-sections.
4. 16MnCr
- A gear steel imported from Germany, equivalent to China’s 16CrMnH, has good hardenability and good machinability, high surface hardness, high wear resistance, and high low-temperature impact toughness;
- Commonly used for larger parts, such as gears, gear shafts, worms, seal sleeves, turbine oil seals, gasoline sleeves and bolts, etc.;
- Tensile strength 880-1180; Yield strength 635; Elongation 9; Hardness ≤297HB;
- Heat treatment specification: 900°C oil quenching + 870°C oil quenching, 200°C tempering.
5. 20MnCr
- A carburizing steel imported from Germany, equivalent to 20CrMn in China, can be used as quenched and tempered steel. Good hardenability, small heat treatment deformation, good low temperature toughness, good cutting performance, but poor weldability;
- It can be used for parts with small cross-section, medium pressure and no large impact load, such as gears, shafts, connecting rods, rotors, sleeves, friction wheels, worms, main shafts, couplings, universal couplings, adjustments The sleeve of the speed controller and the bolts of the cover plate of the high-pressure vessel, etc.;
- Tensile strength 1482; yield strength 1232; elongation 13; impact toughness value 73; hardness 357HB;
- Heat treatment specification: 900°C oil quenching + 870°C oil quenching, 200°C tempering
6. 20CrMnTi
- Carburized steel. The hardenability is high, the machinability is good, the machining deformation is small, and the fatigue resistance is good. Has high low-temperature impact toughness and medium weldability;
- It is mostly used in automobile transmission gears, which can be used as gears, gear shafts, ring gears, cross heads, etc.; important parts with a cross section of less than 30mm, such as gears, ring gears, gear shafts, sliding bearings, main shafts, claw clutches, worms, cross heads, etc.;
- Tensile strength≥1080(110); Yield strength≥835(85); Elongation≥10; Impact energy≥55; Impact toughness value≥69(7); Hardness≤217HB;
- Heat treatment specification: Quenching: first time 880℃, second time 870℃, oil cooling; tempering 200℃, water cooling, air cooling.
7. 20MnMo
- Good welding performance. The chemical composition of SA508-3cl.2 steel is very similar;
- Used for medium temperature and high pressure vessels, such as head, bottom cover, cylinder, etc.;
- Tensile strength ≥470; Yield strength ≥275; Elongation ≥14; Impact energy ≥31.
8. 25CrMo4
- High strength and toughness, high hardenability, no temper brittleness, very good weldability, low tendency to form cold cracks, good machinability and cold strain plasticity.
- Generally used in quenched and tempered or carburized and quenched state, it is used to manufacture high-pressure pipes and various fasteners that work in non-corrosive media and media containing nitrogen and hydrogen mixtures with a working temperature below 250 ℃, and higher-level infiltration Carbon parts, such as gears, shafts, pressure plates, piston connecting rods, etc.;
- Tensile strength ≥ 885 (90); Yield strength ≥ 685 (70); Elongation ≥ 12; Impact energy ≥ 35; Impact toughness value ≥ 98 (10); Hardness ≤ 212HB;
- Heat treatment specification: quenching at 880℃, water cooling, oil cooling; tempering at 500℃, water cooling, oil cooling.
9. 35CrMo
- High creep strength and durability at high temperature, long-term working temperature can reach 500 ℃; moderate plasticity during cold deformation, poor weldability; low temperature to -110 ℃, with high static strength, impact toughness and high fatigue strength, Good hardenability, no tendency to overheat, small quenching deformation, acceptable plasticity during cold deformation, medium machinability, but there is the first type of temper brittleness, and the weldability is not good. It needs to be preheated to 150~400 degrees Celsius before welding. Post-weld heat treatment to eliminate stress. Generally used after quenching and tempering, it can also be used after high and medium frequency surface quenching or quenching and low and medium temperature tempering;
- Mainly used to manufacture important parts in various machines that bear impact, bending and torsion, and high loads, such as large section gears, heavy transmission shafts, steam turbine engine rotors, main shafts, supporting shafts, gears, crankshafts, crankshafts, hammer rods, Connecting rods, fasteners, high-pressure seamless thick-walled conduits, etc.;
- Tensile strength ≥ 985 (100); Yield strength ≥ 835 (85); Elongation ≥ 12; Reduction of area ≥ 45; Impact energy ≥ 63; Impact toughness value ≥ 78 (8); Hardness ≤ 229HB;
- Heat treatment specification: quenching 850℃, oil cooling; tempering 550℃, water cooling, oil cooling.
10. 42CrMo
- It has good mechanical properties and workability, and its strength and hardenability are higher than 35CrMo;
- Used to manufacture forgings with higher strength or larger quenched and tempered section than 35CrMo steel, such as large gears for locomotive traction, supercharger transmission gears, rear axles, connecting rods, reducers, connecting shaft universal couplings and 8.8 grades , Bolts, nuts, washers, etc. in diameter up to 100mm;
- Annealing hardness 255～207HB, quenching hardness ≥60HRC;
11. 50CrMo
- Strength and hardenability are higher than 42CrMo, generally used after quenching and tempering. Can replace quenched and tempered steel with higher nickel content;
- Used to manufacture forgings with higher strength or larger section than 42CrMo steel, such as large gears for locomotive traction, supercharger transmission gears, rear axles, engine cylinders, 1200~2000m oil deep well drill pipe joints, fishing tools, piston rods and Grade 8.8 fasteners with a diameter of 100~160mm;
- Heat treatment process: quenching 850°; coolant: oil; tempering temperature 560°; coolant: water, oil;
- The tensile strength is MPa1080; the yield point is MPa930; the elongation is 12, the reduction of area is 45, and the impact absorption is 63;
12. 20CrMnMo
- High-grade carburized steel, strength higher than 15CrMnMo; slightly lower plasticity and toughness, higher hardenability and mechanical properties than 20CrMnTi; good comprehensive mechanical properties and low temperature impact toughness after quenching and tempering; higher after carburizing and quenching It has high bending strength and wear resistance, but it is prone to cracks during grinding; poor weldability, suitable for resistance welding, preheating before welding, and tempering after welding; good machinability and hot workability. Can be used instead of 12Cr2Ni4;
- Commonly used to manufacture large and important carburized parts with high hardness, high strength, high toughness and wear resistance, such as crankshafts, camshafts, connecting rods, gear shafts, gears, pin shafts, etc.;
- Tensile strength ≥ 1180; Yield point ≥ 885; Elongation after fracture ≥ 10; Section shrinkage ≥ 45; Impact absorption work ≥ 55; Brinell hardness ≤ 217;
- Heat treatment: quenching heating temperature of 850℃; tempering heating temperature of 200℃;
13. 18MnMoNb
- High temperature resistance below 500~530℃, good welding and processing performance;
- Commonly used in chemical high-pressure vessels, hydraulic cylinders, hydraulic turbine shafts, etc. Low-alloy structural steel for boilers and pressure vessels. It has high strength and yield ratio, good thermal processing performance and medium temperature performance, simple production process, good welding performance, and high heat resistance. Used in the manufacture of high-pressure boiler steam drums and large chemical containers; also used as large shafts of hydraulic turbines and hydro-generators, and AC and DC motor shafts;
- Tensile strength ≥635; Yield strength ≥510; Elongation 17; Room temperature impact toughness value 69;
- Heat treatment specification: general normalizing + tempering treatment: 950～980℃ normalizing, heat preservation 1.5min～2.0min/mm, 600～650℃ tempering, heat preservation 5min～7min/mm, air cooling.
14.42MnMoV
- Quenched and tempered low alloy steel. Can replace 42CrMo;
- Mainly used to make shafts and gears, etc.;
- The surface quenching hardness is 45~55HRC; tensile strength ≥765; yield strength ≥590; elongation ≥12; reduction of area ≥40; impact energy ≥31; hardness 241-286HB.
Source:Mechanical professional literature.
Editor:Ali
Post time: Nov-16-2021