Designation by Standards
|Brand Name||Ravne No.||Mat. No.||DIN||EN||AISI|
Chemical Composition (in weight %)
One of the most popular and widely used carborizing steels available. 20MoCr4 is a hardenable chromium, molybdenum, nickel low alloy steel often used for carburizing to develop a case-hardened part. This case-hardening will result in good wear characteristics.
Gears, shafts and other applications where a hard carborized case and a tough core are desired.
Physical properties (avarage values) at ambient temperature
Modulus of elasticity [103 x N/mm2]: 210
Density [g/cm3]: 7.85
Coefficient of Linear Thermal Expansion 10-6 oC-1
Heat to 650-700oC, cool slowly. This will produce a maximum Brinell hardness of 207.
|Case hardening||880-980oC||Oil (water), hot bath 160-250oC|
|Carburising||880-980oC||Oil (water), hot bath 160-250oC|
|Direct hardening||860-900oC||Oil, hot bath 160-250oC|
|Core refining||860-900oC||Oil, hot bath 160-250oC|
|Core refining||780-820oC||Oil, hot bath 160-250oC|
Click the image to enlarge the diagram.
Hot forming temperature: 1050-850oC.
Machining is done prior to carburizing to within as close a tolerance as possible. Finish machining, after heat treatment and/or carburizing, should be at a minimum so as not to impair the hardened case of the part. Machining may be done by conventional means prior to heat treatment - after carburizing machining is usually limited to grinding.
The alloy may be welded by conventional methods, usually gas or arc welding. Preheating at 200oC is beneficial and subsequent heating after welding is recommended - consult the approved weld procedure for the method used.
The alloy may be cold worked in the annealed condition by conventional methods. Cold working, as with machining, should be done to as close a tolerance as possible before heat treatment or carburizing.