25SiMn2MoV Structural Steel Bar

 

25SiMn2MoV is an alloy structural steel. Low-carbon martensitic hardened steel with high strength and high toughness. The performance of 25SiMn2MoV structural steel is basically the same as that of 20SiMn2MoV steel. But the strength and hardenability are slightly higher than 20SiMn2MoV, while the plasticity and toughness are slightly lower. The use is basically the same as 20SiMn2MoV steel. The oil rig rings and other parts made of this steel have good performance, and are safer and more reliable than similar parts made of 35CrNi3Mo and 40CrNiMo , and are light in weight and save materials.

 

This steel has a high degree of hardenability and is completely hardened in oil to 60 to 80 mm (> 95% martensite) diameter (85% martensite at 100 mm diameter center) and fully hardened in water to a diameter Up to 110 ~ 120mm (> 95% martensite) (85% martensite in the center of 160mm in diameter).

 

This steel heat treatment process is good, the oil quenching deformation and cracking tendency is small, decarburization tendency is low, forging process performance is good, the weldability is good, but the shape of complex parts should be preheated before welding to 300 ℃, after welding to slow cooling . The biggest drawback is its poor machinability. This steel is usually used in the quenched and tempered condition. Compared with 35CrMo quenched and tempered steel, its ductility and toughness are generally the same, but the strength is significantly increased, of which the strength limit increased by about 50%; compared with 40CrNiMo quenched low temperature tempered steel, although slightly lower strength, but ductility Especially in the impact value is much higher; compared with 40Cr quenched and tempered steel, low-temperature impact value of -60 ℃ 5 times higher; its static load gap sensitivity is generally comparable with quenched and tempered steel, but with the same strength quenching Compared with medium-temperature tempering and isothermal quenching medium-carbon structural steel, the notched effect is much lower. Compared with medium-tempered middle-temperature tempering, medium-temperature tempering and high-temperature tempering, the fatigue notch sensitivity is also low. Compared with 35CrMo  quenched and tempered steel, overload sensitivity (ie overload fatigue sensitivity) is low; compared with other steels of equal strength, the fracture toughness is quite high

 

As a new type of high strength and toughness structural steel, this kind of steel is used in machinery manufacturing to make long-term running parts with large cross section, heavy load, complicated stress state or low temperature. For example, the light weight Rings, elevators, perforators and so on.

 

Chemical Composition:

 
C(％)Si(％)Mn(％)P(％)S(％)Mo(％)V(％)
0.22～0.280.90 ~ 1.202.20 ~ 2.60≤ 0.030≤ 0.0300.30～0.400.05 ~ 0.12

 

Mechanical Propoerties:

 
Yield Strength
Rp0.2(MPa)		Tensile Strength
Rm(MPa)		Elongation δ5 (%): Reduction
of area ψ (%):		Impact energy
Akv (J):		Impact toughness
value αkv (J/cm2)		 Hardness
≥ 1350 ≥ 1470 ≥ 10≥ 40≥ 40≥ 47≤ 269HB

 

Heat treatment:

  • The first quenching heating temperature (℃): 900; coolant: oil
  • The second quenching heating temperature (℃):-
  • Tempering heating temperature (℃): 200; Coolant: water, air

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