SAE 4340


The GGD 4340 steel is a steel processing with high hardenability, linked to chromium-nickel-molybdenum, used in the manufacture of various mechanical components, including thick sections, when you want a combination of average strength and fracture resistance. It also has high resistance to fatigue.

Chemical composition – C (0.38 – 0.43), Si (0.15 – 0.30), Mn (0.60-0.80), Cr (0.80 – 1.10), Ni (1 , 65-2.00), Mo (0.20-0.30)
Supply conditions – Supplied with maximum hardness of 260 HB. Provided in the temperate state and tempering under consultation.


It is used in mechanical systems components, primarily structural, where need a hardness uniformity throughout the cross section large or small sections. Its main applications are: shafts, gears, planetary gears, columns, sleeves and cylinders.


The GGD 4340 steel should be held at a minimum temperature of 900 ° C 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 860 – 880ºC 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 about 70 ° C. The tempering temperature must be selected according to the hardness specified for the component. To use this tempering Arrangement curve. Keeping the tempering temperature for at least 1 hour for each 25 mm thick and used for at least two hours. No tempering in the temperature range between 230-370ºC because of the possibility of inducing the fragility of the revenido.Curva TemperabilidadeAs 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. 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.

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