There is a wrong method to test the surface hardness of stamping die steel after heat treatment, which is worth correcting. This is the improper use of Richter hardness tester in this case. This is determined by the principle of Richter hardness tester. The three commonly used hardness testers Brinell, Rockwell and Victoria all adopt the static testing principle, that is, a hard indenter is slowly pressed into the sample surface, and then the indentation depth or size is tested to determine the hardness value. Richter hardness tester adopts dynamic testing principle.
It uses a ball with a specified mass to hit the surface of the sample at a specified speed, and tests the difference between its initial speed and its rebound speed to determine the hardness value of the sample. To understand this, just look at the thickness of the standard hardness block of Richter hardness tester. Obviously, the hardness measured by it is neither the hardness of nitride layer nor the hardness of matrix, but the result of their joint action. Due to the different thickness of the surface layer of stamping parts, different results will inevitably be obtained.
The main materials of stamping die in Nantong Zhuo Yue Company are die steel (including tool steel and high-speed steel), which sometimes requires cemented carbide stamping die to have high hardness and wear resistance, so heat treatment is essential.