Optimization of Die Material and Its Surface Coating for Press Forming Magnesium Alloy

Grain sizes of die material and die surface coatings were examined with the achieving mass-production of magnesium alloys by advanced continuous press forming. The results showed that there is an optimum tungsten carbide grain size of 1 to 2 (mu)m for press-forming AZ31 magnesium alloy in terms of surface roughness fluctuation. It was also shown that the adherence of the DLC coating was improved by implanting C ions into the tungsten carbide surface. 10,000 times square-cup drawings were successfully achieved at 543 K using C-ion implantation and a DLC coated die together with a newly developed heat-resistant lubricant.