The GGD 4140 steel is a steel processing with medium hardenability, linked to chromium and molybdenum, used in the manufacture of various mechanical components where you want a good combination of average strength and fracture resistance. It also has high resistance to fatigue.
Chemical composition – C (0.38 – 043) Si (0.10 – 0.35), Mn (0.75-1.00), Cr (0.80-1.10), Mo (0.15 – 0.25)
Supply conditions – Supplied with maximum hardness of 340 HB. Provided in the temperate state and tempering under consultation.
It is used in components for mechanical systems commonly used where the use of the SAE 1045 steel does not apply as a consequence of their better hardenability in larger cross sections, resistance to fatigue and fracture. Used in bearings, cylinders, gears, hydraulic shafts, drilled shafts, rings, nuts and bolts, rods, etc.
The GGD 4140 steel should be held at a minimum temperature of 925ºC and a maximum of 1220ºC.
Annealing: The treatment should be done at the temperature of 850 ° C for at least 1 hour for every 25 mm. Cool slowly in the oven.
Standardization: The treatment should be done at the temperature of 870 – 900 ° C for at least 1 hour for every 25 mm. Cool air. In special cases can use forced air.
Temper: austenize in temperature between 840 – 870ºC. Heat for 1 hour for each 25 mm thick and add 1 additional hour for each 25 mm. Cool in oil or polymer. Cooling polymer leads to smaller dimensional change and improved microstructural homogeneity.
Tempering: It must be done immediately after hardening when the temperature reaches ~ 70 ° C. The tempering temperature must be selected according to the hardness specified in the component. For this use the tempering curve. Keeping the tempering temperature for at least 1 hour for each 25 mm thick and used for at least two hours. No tempering between 230-370ºC because of weakness to tempering.
Nitriding: The steel can be nitrided to increase the wear resistance of the surface hardening. The maximum hardness depends on the precondition of heat treatment. benefit components before nitriding have better hardening characteristic reaching next maximum hardness of 800 HV. It is recommended hardening depth of between 0.30 and 0.60 mm.
Surface Hardening: Can be performed by flame or induction process to hardness greater than 55 HRC.