What is the principle of metal heat treatment
The role of heat treatment
A large number of spare parts used in machine tools, automobiles, motorcycles, trains, mines, petroleum, chemical industry, aviation and aerospace need to be improved through heat treatment. Refuse to preliminary statistics, in the manufacture of machine tools, about 60% ~ 70% of the parts after heat treatment, in the manufacture of automobiles, tractors, need heat treatment of parts of up to 70% ~ 70%, the mould and rolling bearing, heat treatment is 100%. In a word, all important parts must be properly heat treated before they can be used.
What is the principle of metal heat treatment in vacuum furnace?
Heat treatment of a material usually refers to the process of heating the material to a phase change above the phase change temperature, followed by cooling. Through this phase change and rephase change, the internal structure of the material has changed, and thus the performance has changed. Such as carbon tool steel T8 on the market to buy back the spheroidizing annealing material its hardness is only 20 HRC, as a tool subject to quenching and low temperature tempering hardness up to 60 ~ 63 HRC, this is because the internal organization by quenching before spheroidal pearlite into tempered martensite after quenching and low temperature tempering. The heat treatment process of the same material is different. A diameter of 45 steel in table 6-1 F15mm uniform garden bar material after annealing, normalizing, quenching and low temperature tempering and high temperature quenching and tempering of the mechanical properties after different heat treatment, the causes of performance differences so big is distinct internal organization after different heat treatment. The heating temperature and cooling conditions of the same type of heat treatment (such as quenching) are determined by the composition of the material. These show that the heat treatment process (or system) to choose according to the composition of the material, material changes in internal organization depends on the heat treatment and other hot working process, the change of material performance depends on the internal organization change of material, material composition - processing - structure - performance in accordance with each other into the relationship between the four throughout the whole process of material processing. Mesh belt furnace
Basic elements of heat treatment
There are three basic elements in heat treatment process: heating, heat preservation and cooling. These three basic elements determine the structure and properties of the material after heat treatment. Vacuum furnace
Heating is the first process of heat treatment. Different materials have different heating processes and temperatures. There are two types of heating. One is heating below the critical point A1, when no tissue changes. The other is heating above A1 to get even austenite tissue, a process called austenosis. Carbide furnace
The purpose of heat preservation is to ensure that the workpiece burns through to prevent decarbonization, oxidation, etc. The choice of insulation time and medium is directly related to the size and material of workpiece. The larger the workpiece, the worse the thermal conductivity, the longer the thermal insulation time. Vacuum furnace
Cooling is the final process of heat treatment and the most important process of heat treatment. Steel can change into different tissues at different cooling rates.
Basic types of heat treatment
Heat treatment can be divided into the following categories according to different heating and cooling methods, as well as different characteristics of tissue and performance changes:
1. Common heat treatment includes annealing, normalizing, quenching and tempering, etc. Quenching furnace
2. Surface heat treatment includes surface quenching by induction heating, surface quenching by flame heating, surface quenching by electric contact heating, carburizing, nitriding and carburizing.
3. Other heat treatments include controllable atmosphere heat treatment, vacuum heat treatment and deformation heat treatment. Sintering furnace
According to the position and function of heat treatment in parts production, the heat treatment process can also be divided into preliminary heat treatment and final heat treatment. Prepare heat treatment is the intermediate process in the process of parts processing (also known as the intermediate heat treatment), its purpose is to improve the forging and casting blank parts organization, eliminate stress, to prepare for the subsequent machining or further heat treatment. The final heat treatment is the final process of part processing. The purpose of this process is to make the performance of the parts after the required shape and size through the forming process reach the required performance
Label: sintering furnace carbonization furnace net belt furnace vacuum furnace