The GGD D2 steel is a tool steel for cold work most frequently used in the metal and mechanical industry, particularly in the forming and cutting industry frio.Pode be heat treated to high hardness while maintaining good resistance to fracture. It is a steel with high hardness in the penetration hardness and excellent dimensional stability and shape. It is able to combine two different heat treatment cycles, thereby allowing the subsequent use of surface treatments such as nitriding and PVD coating. Due to its structure, chromium-containing hard carbides and a high hardness after heat treatment, the steel GGD D2 has excellent wear resistance as much abrasive as adhesive.
Supply conditions – Supplied in the annealed condition with a maximum hardness of 255 HB.
The steel GGD D2 tool is used matrices and forming and cutting punches. Tools for folding, fountain, extrusion, rolling threads combs and knives in general. In making molds for forming ceramic pieces and molds for plastic injection technical high abrasiveness.
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. Cool slowly in the oven to 300 ° C and then in still air.
Temper: austenize in temperature between 1020-1040ºC. 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 for austenitization to be performed two pre-heating to ensure temperature uniformity and minimize distortion.
Tempering: It must be done immediately after hardening when the temperature reaches about 70 ° C. According to the tempering curve steel GGD D2 can be selected two temperature ranges, 200 and 540ºC for a typical hardness of 58-60 HRC. The selection of thermal treatment cycles must take into account the characteristics of each application tool, but tempering at elevated temperature always leads to increased fracture resistance. In any case, they must be made at least two tempering. In critical wear applications can be used with hardness greater than 60 HRC. When the material is subsequently nitrided or PVD coated, tempering shall be performed at high temperature.
Sub-zero treatment: In certain situations, tools may be subjected to this treatment to ensure maximum dimensional stability. The cooling should be done in close temperatures – 90 ° C. Most of the time is used for tools that are coated with PVD. The sub-zero treatment can lead to generation of cracks and must be conducted with full technical control.
Nitriding: The steel can be nitrided to increase the wear resistance of the surface hardening. In the case of steel GGD D2 nitriding can not lead to the formation of White Layer by weakening the nitrided surface. The maximum hardness after nitriding is the 1200HV order.
EDM and grinding: The steel GGD D2 is susceptible to the appearance of cracks after these processes. When performed outside the box, the EDM and grinding can cause retempers surface, deteriorating the heat treatment in the region and lead to the formation of cracks. In extreme cases it can cause loss tool. If necessary perform a new tempering after finishing tool.