Heat treatment of high speed steel
The importance of the requirements for heat treatment to the requirements for heat treatment depends on a variety of factors, such as further processing of parts, scope of application, value of finished workpieces or cutting tools. Generally speaking, the following indicators are decisive:
(L) small deformation;
(2) no environmental pollution.
(3) the heat treatment time is short and the cost is low.
(4) strong adaptability;
(5) the results are stable.
The above requirements are easier to achieve in heat treatment of vacuum devices than other heat treatments. Small deformation and no environmental pollution are the main advantages of modern vacuum heat treatment equipment, which is of great significance to quenching of high speed steel. Since most of the heat treatment of cutting tools is carried out after machining, it has already cost a lot of manufacturing costs, so it is very important to keep the stability of the processing quality and record the processing process.
Two, practical application
1. no environmental pollution size is medium 30OX420mm. Because the hob has been processed, so quenching, in addition to ensuring a good metallurgical properties, but also pay attention to small deformation. The quenching process includes heating the enzyme to 850 the first preheating stage the second preheating stage 050 and austenitizing and rapid cooling at 500. The schematic diagram of the heat treatment process is to reduce the temperature difference inside the workpiece to a minimum by convection heating. In addition, compared with the radiation heating, the heating time is greatly reduced, and the economy of the equipment is improved. When cooling, the cooling pressure (3.8 bar) can be used to ensure that the cylindrical gear hob can be completely quenched. Isothermal salt bath (temperature is 500 C) is used to eliminate stress and reduce temperature difference (up to Ms). After quenching, the tempering at 5 tap XL h for three times was carried out at 2 barium nitrogen pressure. The precise measurement of the hob shows that the deformation after heat treatment is very small, and the deviation is within the measurement tolerance. The hardness was v830~8 (0) (~HRc65). It is indisputable that vacuum quenching without environmental pollution is of great significance for improving the ecological environment. At this time, many new Qing salt bath equipment in Western Europe, due to the low cost can get some supplementary praise, surface vacuum equipment energy consumption is low, and ultimately can be considered as a contribution to environmental protection.
2. automation can be realized in vacuum equipment. Heat treatment is usually done automatically through program control. The high repeatability of heat treatment process and result is guaranteed by modern microprocessor technology, corresponding guarantee device and thermocouple control process of furnace charge. The temperature measurement of the burden can record the process accurately.
3. small deformation and small deformation is one of the most important prerequisites for achieving satisfactory heat treatment. By selecting the appropriate heat treatment parameters and the corresponding loading way, the deformation of the workpiece can be greatly reduced. Two methods of treating 56-15-12-15 (material code 13243) cylindrical gear hob, hob-i-tian-1, warship turning and quenching gloss-time curve long yarn charging, due to the high austenitizing temperature of high speed steel, play an important role. Broaches should normally be hoisted, and long and thin milling cutters and drills should also be hoisted. Hob and small twist drill can be installed, but the drill bit should be installed vertically. The box load is Lin's. By quenching a thin disk milling cutter (for example, 6 "x3.3x cut mm material 56-5-12, material code 1.33J3), it is concluded that the loading mode has an effect on the deformation of the workpiece. The workpiece remains 10 minutes at the austenitizing temperature (1190 dead). The cooling pressure is 2 bar. "There are three different ways of loading:
(l) Fixing the milling cutter horizontally between the sheets; and (2) Fixing the milling cutter vertically between the sheets;
(3) put the milling cutter on the steel pipe vertically. Horizontal placement makes the deformation of the workpiece larger () 0.3 mm, while vertical placement improves the deformation of the workpiece significantly. The deformation at single loading is 0.1 mm, and the deformation is O~O, LMM when the disc cutter is fixed between the thin plates. The hardness of the milling cutter fixed between plates is slightly lower than that of RC65 (HRC66), due to a decrease in cooling rate. The total deformation can be reduced by more than 2/3 compared with salt bath quenching.
4. Convective heating of adaptable and economical tools can greatly reduce the time and cost of heat treatment. Therefore, modern heat treatment equipment can be very economical for heat treatment. Test results of quenching for different high-speed steel workpieces. Under the condition of full load of equipment, the hardness achieved is within the tolerance range. Most of high speed steel drill bits are packed by cassette.