About: Cathy Liu

20CrMnMo case hardening steel

20CrMnMo steel is a high strength high grade carburizing steel(case hardening steel), alsp known as 20CrMnMo alloy steel.  Its strength is higher than 15crmnmo, its plasticity and toughness are slightly lower, and its hardenability and mechanical properties are higher than 20CrMnTi steel.(20CrMnMo steel vs 20CrMnTi steel)

After quenching and tempering, it has good comprehensive mechanical properties and low-temperature impact toughness. After carburizing and quenching, it will get high bending strength and wear resistance, but it is easy to produce cracks during grinding. Poor weldability, suitable for resistance welding, it need to be  preheated before welding and tempered after welding. Its machinability and thermal workability are good.

20CrMnMo Mechanical properties

Tensile strength (σ B / MPA): ≥ 1180
Yield strength (σ s / MPA): ≥ 885
Elongation after fracture (δ 5 /%): ≥ 10
Reduction of area (ψ /%): ≥ 45
Shock absorption energy (aku2 / J): ≥ 55
Brinell hardness (hbs100 / 3000) (annealed or tempered at high temperature): ≤ 217

1.7765 tool steel

1.7765 steel is a kind of tool steel, which is used for cylinder, valve body, bolt and roll sleeve of important equipment with high speed, high temperature, wear resistance, high strength, high toughness and high fatigue resistance in aviation, power generation, rolling and other industries.

1.7765 material equivalent

1.7765 mechanical properties

Physical properties (average values) at ambient temperature

Modulus of elasticity [103 x N/mm2 ]: 210

Density [g/cm3 ]: 7.82

39NiCrMo3 Alloy steel

39NiCrMo3  steel has high strength, toughness, good hardenability and stability against overheating, but it has high white point sensitivity and temper brittleness. Weldability is poor, high temperature preheating is required before welding, stress relief after welding, and use after quenching and tempering.

39NiCrMo3 equivalent grade

39NiCrMo3 mechanical properties

Tensile strength (MPa)≥980,
ElongationA (%) ≥12,
Reduction of area ≥55,
Impact energy Akv (J)≥78

18CrNiMo7-6 carburized steel

18CrNiMo7-6 steel belongs to Case Hardening Steel(carburized steel). It is a grade consisting of the addition of chromium, nickel, molybdenum with a range characteristic for all carburizing grades.18CrNiMo7-6 material can be used for much larger sizes and loads.

18CrNiMo7-6 equivalent materials

18CrNiMo7-6 mechanical properties——Quenched and Tempered at 200°C

What’s 42CrMo4 steel

42CrMo4 steel belongs to ultra-high strength steel, with high strength and toughness, good hardenability, high fatigue limit and multiple impact resistance after quenching and tempering treatment, and good low temperature impact toughness. The steel is suitable for manufacturing large and medium-sized plastic molds that require certain strength and toughness.

Equivalent steel standard

Application

High hardenability, high strength, good toughness, small deformation during quenching, high creep strength and lasting strength at high temperature. Used to manufacture forgings that require higher strength, such as large gears for locomotive traction, turbocharger transmission gears, pressure vessel gears, rear axles, connecting rods and spring clamps that are heavily loaded, and can also be used for deep well drilling under 2000m Rod joints and fishing tools, and can be used for molds of bending machines, etc.

Chemical composition

C: 0.38～0.45%

Si: 0.17～0.37%

Mn: 0.50～0.80%

S: allowable residual content ≤0.035%

P: allowable residual content ≤0.035%

Cr: 0.90～1.20%

Ni: allowable residual content ≤0.030%

Cu: allowable residual content ≤0.030%

Mo: 0.15～0.25%

Mechanical properties

Tensile strength σb (MPa): ≥1080

Yield strength σs (MPa): ≥930

Elongation δ5 (%): ≥12

Reduction of area ψ (%): ≥45

Impact work Akv (J): ≥63

Impact toughness value αkv (J/cm2): ≥78

Hardness: ≤217HB

*42CrMo4 steel forging heat treatment process

1.42CrMo4 steel forgings require quenching and tempering treatment after forging. Due to the large difference in cross-section size, the tendency of water quenching to crack is greater, the quenching hardness of the large cross-section after oil quenching is lower, and the metallographic structure and mechanical properties are often unqualified, which directly affects the fatigue strength and service life of the crankshaft .

2. With high strength and high yield point, the comprehensive mechanical properties are better than 40Cr. The cold deformation plasticity and machinability are both moderate, and the overheating sensitivity is small, but there is a tendency to temper brittleness and white spot sensitivity. Generally used in quenched and tempered state.

3. The forging process adopts the water-soluble quenching medium quenching process. In order to ensure the normal use of quenching liquid, the temperature of the quenching liquid must be strictly controlled. The inverse melting point of the quenching medium is 70℃, and the best use temperature is (30～60)℃. The temperature of the quenching liquid must always be controlled within the range required by the process.