Heat treatment of workpiece hardness test method - bearing knowledge

Surface heat treatment is divided into two categories, one kind is surface quenching tempering heat treatment, another kind is the chemical heat treatment, the hardness testing method is as follows: 1, the surface quenching tempering heat treatment hardening tempering heat treatment usually use induction heating or heating of the flame. Is the main technical parameters of surface hardness, local hardness and effective hardening layer depth. Hardness test can use vickers hardness tester, rockwell may be adopted or surface rockwell hardness tester. Test ( Scale) The selection and effective hardening layer depth and workpiece surface hardness. Here involves three hardness tester. Vickers hardness tester is an important means of heat treatment of workpiece surface hardness test, it can be used to 0. 5 ~ 100 kg of test force, test thin to 0. 5 mm thick surface hardening layer, and its precision is the highest, can distinguish the tiny difference of heat treatment of workpiece surface hardness. In addition, the effective depth of hardening layer by vickers hardness tester to test, so, for heat treatment processing or use a lot of surface heat treatment of workpiece surface units, equipped with a vickers hardness tester is necessary. Surface rockwell hardness tester is also very suitable for testing surface hardness, quenching workpiece surface rockwell hardness tester has three scale can choose. Can test the effective depth of hardening more than 0. 1 mm of various surface hardening of the workpiece. Although the precision of surface rockwell hardness tester not high vickers hardness tester, but the heat treatment factory quality management and inspection of qualified testing means, has been able to meet the requirements. Besides, it also has a simple operation, convenient use, low price, measurement quickly, can be directly read hardness value etc. , using the surface rockwell hardness tester can be rapidly and heat treatment on the surface of a batch of workpiece inspection one by one. It is of great significance for metal processing and machinery manufacturing factory. When the surface heat treatment hardening layer thicker, rockwell hardness tester may be adopted. When heat treatment hardening layer thickness in 0. 4 to 0. 8 mm, can use HRA scale, when the thickness of hardening layer more than 0. When 8 mm, can use HRC scale. Vickers and rockwell and superficial rockwell hardness value can be mutual conversion, easily convert standard, drawings or hardness value to meet the needs of users. The corresponding conversion table in the international standard ISO, American standard ASTM and China standard GB/T has been given. In shenyang in the technical data section of the three star website conversion table can be found. 2, chemical heat treatment and chemical heat treatment is to make the workpiece surface infiltration of one or more of the following elements of atoms, which changes the surface chemical composition, microstructure and mechanical properties. After quenching and low temperature tempering, surface has high hardness, abrasion resistance and contact fatigue strength, strong and work piece of core with high toughness. The major technical parameters of chemical heat treatment of workpiece is the hardening layer depth and surface hardness. The depth of hardening layer or the vickers hardness tester to test. From the surface to the hardness to 50 HRC that distance. This is the effective depth of hardening chemical heat treatment of workpiece surface hardness testing and surface heat treatment quenching hardness testing, can use vickers hardness tester, surface rockwell hardness tester or rockwell hardness tester to test, only the thickness of nitriding thick thin, generally no greater than zero. 7 mm, then can no longer use the rockwell hardness tester. 3, the local heat treatment parts demand is higher, if the local hardness available locally in the form of induction heating and quenching heat treatment, such parts are often marked the location of the partial quenching heat treatment on the drawing and local hardness value. Parts of the hardness testing needs to be done within a specified area. Hardness testing instrument can be used rockwell hardness tester, hardness value is HRC testing, such as heat treatment hardening layer shallow, can adopt surface rockwell hardness tester, testing HRN hardness value.