The steel GGD H13 is a Tool Steel for Hot Work with an excellent combination of hardness and fracture toughness, with the maintenance of these properties at temperatures up to 600 ° C, resistance to thermal shocks and cracks by thermal fatigue, this steel also has levels machinability, polishability and response to important texturing for the segment of manufacture of molds for plastic injection.
Chemical Composition – C (0.40) • Mn (0.4) • Si (1.0) • Cr (5.0) • Mo (1.30) • V (1.0)
Supply conditions – Supplied in the annealed condition with a maximum hardness of 230 HB.
The combination of their properties, especially at elevated temperatures makes the steel GGD H13 appropriate to use in many different applications such as forging dies hot in presses, dies for aluminum extrusion alloys, die casting or gravity alloys do not ferrous, injection mold abrasive polymers such as thermoset.
Stress relief: In tools of complex shapes, heterogeneous material removal in roughing, sudden changes in sections, etc., should be carried out treating strain relief to minimize dimensional variations and form during the quenching and tempering. The treatment should be between 550 – 650 ° C for at least 2 hours and then cooling slowly in the oven to 200 ° C, then to air.
Temper: austenize in temperature of 1020ºC. Heat for 1 hour for each 25 mm thick and add 1 additional hour for each 25 mm. Cool air, warm oil, salt bath or nitrogen pressure in a vacuum oven. During the heating to the austenitizing should be performed 2 pre-heating to ensure temperature uniformity and minimize distortions. The cooling should be appropriate to the size and geometry of the tools.
Tempering: It must be done immediately after hardening when the temperature reaches about 70 ° C. The tempering temperature should exceed 550 ° C to avoid compromising the fracture resistance. Usually uses approximately 610ºC for a typical hardness of 45 HRC, recommended by the “North American Die Casting Association” for aluminum smelting underpressure. For other hardness levels to select the tempering temperature according to typical steel of this curve. When the material is subsequently nitrided the tempering temperature should be 50 ° C higher than the nitriding temperature.
Quenching from 1020ºC. Double tempering of 2 hours each.
Nitriding: This treatment increases the wear resistance by hardening. The nitrided layer can be designed to take or not the white layer. Selection of the appropriate layer depends on the application of the tool. In general the maximum hardness after nitriding is the 1000HV order. The stiffening profiles after nitriding process, surfaces with and without white layer are shown below