Die steel parts need to be subjected to surface heat treatment, and the hardness tester must accurately measure the hardness of the die steel under different conditions. Hardness tester is indispensable in the hardness test of die steel. Many people do not have a deep understanding of heat treatment, so let's talk about it in detail below.

The Vickers hardness tester is accurate for surface hardened metals with a test surface of 0.05. The test force is 0.5-100kg, which can directly detect the change of the hardness difference of the die steel metal surface. The effective hardening depth of the Vickers hardness tester is used as the measurement object. If steel parts need surface heat treatment, and a large number of unit surface heat treatment workpieces are used, then this kind of hardness tester is indispensable.

When it is necessary to test various surface hardened steel parts with an effective hardening depth greater than 0.1mm, a surface Rockwell hardness tester can be used. The accuracy of the surface Rockwell hardness tester is lower than that of the Vickers hardness tester. According to the inspection level accuracy of general factory parts, the requirements can be met. This type of product has the advantages of low price, fast detection, and convenient use. Rockwell hardness tester can be used for rapid and non-destructive single piece inspection of batch surface heat treatment workpieces. This has brought great convenience to metal processing and machinery manufacturing plants.

If the surface heat treatment hardened layer of the die steel is thick, the Rockwell hardness tester is a good choice. The thickness of the heat-treated hardened layer can be measured with HRA ruler, and the measuring range is 0.4～0.8mm. If the thickness of the hardened layer exceeds 0.8mm, the HRC scale can be used. Vickers hardness, Rockwell hardness and surface Rockwell hardness can be converted to the hardness required by the standard and drawing users.

For locally heat-treated die steel, local hardness requirements are relatively high, and induction heating and other methods can be used for local quenching heat treatment. For such steel parts, the location of the local quenching heat treatment and the local hardness value should be marked on the drawing. The part hardness test should be carried out in the designated area. The hardness tester can use the Rockwell hardness tester to test the HRC hardness value. If the heat treatment hardened layer is shallow, the HRN hardness value can be measured with a surface Rockwell hardness tester.

Some people think that the die steel must be cooled to room temperature after quenching before it can be tempered. For many kinds of steel, low carbon steel and medium carbon steel, the martensitic transformation point is higher than room temperature. When it cools to room temperature, it cracks easily. After quenching, it can be transferred to the tempering process. Determine the furnace temperature after quenching and before tempering according to the martensite transformation point of the steel grade! In order to prevent quenching cracking, we should not guess, but should adopt the method of tempering with temperature.