The role of weld-deposited working layer on the performance of hot forging dies

The performance of hot-forging dies, in which the die cavity is weld-deposited with a layer of modified H12 hot-work tool steel, has been studied, using a continuous monitoring of the die condition as well as macroscopic and microscopic examination. It was observed that the thickness of the hard upper 'capping layer' and that of an intermediate 'buffer layer' have a pronounced effect on the life and performance of forging die. For a given size and shape of the die cavity, there was an optimal thickness of capping layer that would give the best performance; thicker capping layers are likely to exhibit brittle cracking, while thinner layer have a tendency for early deformation and wear. For buffer layer, a certain minimum thickness is needed to provide sufficient backup support. (author)