817M40 Alloy Steel

817M40 is a high tensile alloy steel, usually supplied in the heat treated T condition, although several heat treatments are available with specification limitations on size. The steel exhibits good shock and wear resisting properties. Main uses include gears, bolts and studs, shafts spindles and forgings. The material differs from 709M40 by the significant Nickel content. Nickel helps improve resistance to corrosion and toughness. The material is best machined with carbide tooling.

Chemical Composition

Mechanical Properties

1.Tensile strength: 1020MPa
2.Yield point: 945MPa
3.Percentage reduction of area after fracture: 55%
4.Elongation after fracture: 13%
5.Impact test (+20°C): Transverse – 27~32J; Longitud – 45~50J

Forging EN24/817M40 Steel

Recommended Forging temperature:850℃- 1150℃,and final forging temperature should not below  850℃.Cooling as slowly as possible in the furnace  to prevent surface crack,and annealing immediately after forged is recommended.

Heat Treatment

Normalizing

Normalizing is used to refine the structure of forgings that might have cooled non-uniformly after forged,and considered as a conditioning treatment before final heat treatment.Normalizing temperature for EN24 steel should be carried out between 850℃-880℃ with several steps,keep proper holding time depend on the steel size for the steel to be thoroughly heated to complete the ferrite to austenite transformation.Cool in still air.

Annealing

Annealing is generally applied after forged and before machining to reduce surface harness,and get finer grain,get good machinability.

Soft Annealing:Heat the steel to the temperaure 650℃-680℃,Holding temperature for the steel heating, Cool slowly in the furnace.

Full Annealing:Heat the steel to the temperaure 820-850℃ with three steps ,Holding temperature for the steel heating,Cool in furnace.Surface hardness after annealing will be below 248HB.

Hardening

Hardening temperature is carried out from an austenitizing temperature of 820-850ºC with several steps,keep suitable time for the steel to be thoroughly heated,  oil quenching is recommended.

Tempering

Tempering process should be followed after quenching immediately.Tempering at a suitable temperature not exceeding 660ºC .

Application

EN24/817M40 steel is widely used as engineering steel in Automobile Industry, Construction, Pharmaceutical / Chemical Industry, Oil & Gas Industry.It is often utilized where other alloy steels do not have the hardenability to give the strength required. For highly stressed parts it is also an excellent choice.

Typical Applications:

• Heavy-duty axles &  Shafts
• Punches & Dies
• Studs & Bolts
• Gears & Rings