The production of die steel requires surface heat treatment processing. The hardness tester can accurately measure the die steel under different conditions. Therefore, the hardness tester is indispensable in hardness testing. However, many people do not have a deep understanding of heat treatment. Below we will introduce the hardness testing after heat treatment.
For testing the surface hardening of 0.05-thick hardened metals, the Vickers hardness tester is the most accurate measurement. An experimental force of 0.5 to 100KG can be selected for directly detecting changes in hardness differences on the metal surface of the parts. The effective hardening layer depth is the measurement object for the Vickers hardness tester, which is essential for units that require surface heat treatment processing or use a large number of surface heat-treated parts.
If it is necessary to test various surface-hardened workpieces with an effective hardening depth of 0.1MM or more, a Rockwell hardness tester can be selected. Although the precision of the Rockwell hardness tester is lower than that of Vickers, it can meet the accuracy level required for testing general factory parts. It has the advantages of low price, rapid testing, and convenient use. The Rockwell hardness tester allows for fast and non-destructive single-piece inspection of batches of surface heat-treated workpieces of die steel. This is an extraordinary convenience for metalworking and machine building plants.
In addition, when the surface hardening layer is thick, the Rockwell hardness tester is also a good choice. The HRA scale can be used to measure the thickness of the hardened layer after heat treatment in the range of 0.4 to 0.8 mm. If the hardening layer thickness exceeds 0.8 mm, the HRC scale can be used. The Vickers, Rockwell, and surface Rockwell hardness values are all suitable for mutual conversion, and can be converted into standard, drawing, or user-required hardness values.
For parts treated with local heat treatment, the local hardness requirements are relatively high, and induction heating and other methods can be used for local quenching heat treatment. These parts typically require the location and local hardness values of local quenching heat treatment to be indicated on the drawing. The hardness of the parts must be tested within the specified area. A Rockwell hardness tester can be used for the hardness testing
Some people believe that after quenching out, not yet cooled to room temperature, can not enter the tempering process. In fact, many steel grades, especially low and medium carbon steel, the martensite transformation end point is mostly higher than room temperature, cold to room temperature, but easy to crack, quenched out as soon as possible after the tempering process.
According to the steel martensite transformation point to determine the tempering after quenching before the furnace temperature! In order to prevent quenching and cracking, can not be presumed, a generalized approach to tempering with temperature.
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