The GGD 8620 steel is a steel hardening and further processing linked to nickel, chromium, and molybdenum giving it better hardenability. The carburizing is used to increase the wear resistance of a core of good mechanical strength and fracture toughness. After hardening the surface hardness can reach 62 HRC.
Chemical composition – C (0.17 – 0.23), Si (0.10 to 0.40), Mn (0.60 to 0.95), Ni (0.35 to 0.75), Cr (0 , 35-.75), Mo (0.15-0.25)
Supply conditions – supply with maximum hardness of 260HB
It is used in mechanical components for use as; guide pins, gear rings, columns, crosses, turnstiles, cases, shafts, crowns, crankshafts, eixoscomando, pins, guides, sprockets, gears in general.
The GGD 8620 steel should be performed at the minimum temperature of 900 ° C and a maximum of 1240ºC.
Annealing: The treatment should be done at temperatures between 820 – 840ºC for at least 1 hour for every 25 mm. Cool in forno.Normalização: Treatment should be done at the temperature of 910 – 930ºC for at least 1 hour for every 25 mm. Cool air. In special cases can use forced air.
Carburizing: the hardening process can be used in cash, gas or salt bath. The temperature should be between 900 – 925ºC. The hardening time should be controlled according to the carbon potential and the hardening depth specified. The cementation should be followed by improvement.
Tempering: Tempering when performed directly after hardening, lowering the temperature to 840 – 860ºC, keeping the time necessary to homogenize the temperature in cross section and cooling in oil or water depending on the section and geometry. To use the conventional tempering temperature of 840 – 870ºC with the same procedure described.
Tempering: It must be done immediately after hardening when the temperature reaches about 70 ° C. The tempering is performed at temperatures between 150 – 200 ° C. The tempering there is no significant drop in hardness, but it ensures better resistance to fracture and the formation of surface cracks on grinding. The information contained in this catalog are indicative, depending on the characteristics of the raw material and test conditions.
Nitriding: The steel can be nitrided to increase the wear resistance of the surface hardening. For nitriding the component should only be hardened and tempered or annealed. It is essential the presence of the white layer with a thickness exceeding 12 mm.
Quenching Surface: This steel does not respond satisfactorily, because it has very low carbon content.