The main purpose of carburizing heat treatment for automobile parts of aluminium alloy is to obtain good fatigue resistance and wear resistance of parts and to ensure the reliability of Parts'performance. The heat treatment parts strengthened by carburizing and quenching include differential gear of automobile driving axle, transmission axle gear, steering axle gear, engine piston pin and gear parts, etc.

Carburizing heat treatment equipment for automobile parts mainly includes box multi-purpose furnace, single-row, double-row and multi-row continuous furnace, vacuum (low pressure) carburizing high pressure gas quenching furnace, etc. Over the past decade, the important sign of the development of carburizing heat treatment technology is the application of sensing technology and computer technology in production. For the process parameters of carburizing heat treatment, such as temperature, time, carbon potential, quenching process and action program, the system can automatically generate process and realize intelligent control according to the technical requirements of parts, material grades and characteristics.

Quenching and tempering heat treatment

The quenching and tempering heat treatment of automobile parts can be divided into protective atmosphere quenching and tempering heat treatment and general quenching and tempering heat treatment. Protective atmosphere heat treatment can ensure that parts will not produce surface oxidation, decarbonization and other defects in the process of heat treatment, and ensure the surface quality of parts. When the workface of the parts after quenching and tempering needs follow-up processing, general heat treatment is adopted. According to the quality and size of the parts, the quenching and tempering heat treatment equipment includes mesh belt furnace, chain casting furnace, tray (basket) push rod furnace, bracket furnace, suspended continuous furnace, etc.

Induction heat treatment

Compared with general furnace heat treatment, induction heat treatment has the following characteristics:

(1) According to the performance requirements of the product, only the surface or local heating of the parts, surface or local strengthening is carried out, so it is an energy-saving heat treatment.

(2) The production process is pollution-free and clean heat treatment.

(3) The induction heating time is short and the speed is fast, which is conducive to the refinement of quenching structure and the strengthening effect with good wear resistance and torsion bending fatigue resistance.

(4) The induction quenching device can be easily installed on the production line, which is convenient for production management and reduces the logistics cost.

(5) Induction hardening production is fast, efficient and can achieve complete automation.

These characteristics of induction heat treatment make induction hardening technology widely used in automotive parts production. At present, induction hardening of automotive parts is mainly used to transfer power torque of automotive shaft parts, such as crankshaft, half-shaft, spline shaft, transmission shaft, camshaft and various pin parts.

Heat Treatment of Forging Waste Heat

Hot forging process is used for most automotive structural parts. How to use the waste heat of forging to heat the blank is an important measure to save energy. If isothermal annealing of forging waste heat and quenching of forging waste heat can be used, the structure and hardness needed for subsequent processing can be obtained, and the energy consumption of reheating heat treatment can be saved. The energy saving effect is remarkable. The parts which are heat treated by forging waste heat include all kinds of gear blanks, front axles, steering knuckles, rocker arms, spline shafts, crankshafts, connecting rods, etc. For the isothermal annealing of tooth blanks, in order to ensure the homogeneity of structure and hardness of forging heat treatment, the final forging temperature, intercooling process and isothermal temperature should be strictly controlled. In order to ensure the strength and toughness of the parts quenched by waste heat, besides the direct quenching process, the method of pre-cooling to 550-650 C and reheating to austenitizing temperature after pearlite transformation can also be used. The main purpose is to refine the structure and obtain good strength and toughness.

Annealing-free cold heading steel and non-quenched and tempered steel

In order to ensure cold forming performance of cold heading steel, spheroidizing annealing is required in advance. The so-called annealing-free cold heading steel is that by adjusting the chemical composition of cold heading steel and controlling rolling and cooling technology in the rolling process, the pearlite part is spheroidized and deformed, and the deformation resistance in the cold forming process is reduced. It can be directly used in cold heading forming. Since spheroidizing annealing is not necessary, it not only has remarkable energy-saving effect, but also shortens the production cycle. It is an energy-saving and economic new material.

Non-quenched and tempered steel has precipitation strengthening and grain refinement during forging and controlled cooling after forging due to the addition of trace strong carbon (nitrogen) forming elements (V, Nb, Ti etc.) in the steel. Its strength and toughness can reach or close to the level of quenched and tempered steel, and the quenched and tempered heat treatment process is omitted, a large amount of energy consumption is reduced and good processing performance is obtained by many automobile factories at home and abroad. Home attention. For example, German Benz and Volkswagen Automobile Company, Swedish Volvo Automobile Company, British Aust in Company, American G.M. Ford Automobile Company and Italian Fiat Automobile Company use a large number of non-quenched and tempered steel to manufacture engine crankshaft, connecting rod, front axle and other important parts. Japan is ahead of the world in the research and application of non-quenched and tempered steels, such as steering system and transmission system of Mitsubishi Automobile Company of Japan, which almost all hot forgings are made of non-quenched and tempered steels, and crankshafts and connecting rods of Nissan, Isubishi Automobile Company almost all are made of non-quenched and tempered steels. Over the past decade, Dongfeng Automobile Company has used non-quenched and tempered steel to produce crankshaft, connecting rod, automobile front axle, steering knuckle and other parts. It uses tens of thousands of tons of non-quenched and tempered steel annually. It has produced millions of automobile parts such as crankshaft, connecting rod and front axle, which has achieved remarkable economic and social benefits.

Application Equipment for Heat Treatment of Automobile Parts

Heat treatment has become an indispensable and increasingly important processing method in modern industry. Therefore, the development of induction heating equipment is also growing. Choosing good heating equipment can double the work with half the effort. There are several kinds of heat treatment equipment commonly used in industry for automobile parts.