In order to improve the comprehensive properties of metal parts, it is necessary to process them by hardening heat treatment furnace After processing, metal parts with high hardness, strength and wear resistance can be obtained.
Parts are quenched by heat treatment from austenitizing temperature, which should be cooled rapidly at a rate greater than the critical cooling rate to obtain the required microstructure and properties. In the region of austenite, the thermal stress is produced and the surface layer is compressed. When the temperature falls below the Ms point, the austenite transforms into martensite to produce the transformation stress, while avoiding its decomposition, it can also prevent the cracking of the parts, and when the temperature falls below the austenite point, the austenite is transformed into martensite. The greater the cooling rate is, the greater the phase transformation stress is, and the higher the tensile stress on the surface of the part is. Therefore, when the difference between the phase transformation stress and the thermal stress exceeds the fracture strength of the material, it will lead to quenching and cracking. In the actual production process, it is necessary to cool slowly in this area as far as possible, in order to harden but not crack, that is to say, the nose of the C curve is rapidly cooled, and the martensitic transformation region is slowly cooled.
In the course of quenching, in order to reduce the deformation of parts and avoid cracking, the selection of heating temperature, holding time, quenching method and quenching medium should be carried out correctly, and the chemical composition, structural size and shape of the parts should be fully considered at the same time. Specific technical requirements, parts immersed in quenching medium method is particularly important.
Overseas manager: Tom Wang
Phone: 0086-13303078975(whatsapp, wechat,line)
Specialist of bar heat treatment furnace in China; Glad to be your business partner in induction heating field.
Post time: 04-25-2019