Vacuum carburizing process of auto parts

---

The main purpose of carburizing heat treatment is to obtain good fatigue resistance and wear resistance of the parts, and to ensure the reliability of the performance of the parts. The heat-treated parts strengthened by carburizing and quenching include: differential gears of automobile drive axles, transmission shaft gear parts, steering gear shaft gear parts, engine piston pins and gear parts, etc.Our country’s automotive gear steels include: 16MnCr5, 20MnCr6, 27MnCi5 and other Mn-Ci series gear steels; SCM822H, SCM420H and other Cr-Mo series gear steels; 20CMnB (ZF7)，16CiMnB(F6) and other Cr-Mn-B series gear steels; 2OCrNiMo, 22CNiMo and other Cr-Ni-Mo series gear steels and 20CnMnTiH series gear steels. The technical standards of automobile gear steel materials generally require that the hardenability bandwidth should be controlled within 7HRC, and the hardenability bandwidth of high-grade gear steel should not be greater than 4HRC. The purity of gear steel generally requires [O]≤2×10-5, high-purity gear steel requires [O]≤1.5×10-5, and the grain size is required to be equal to or finer than grade 6.

Carburizing heat treatment equipment for auto parts mainly includes box-type multi-purpose furnaces, single-row, double-row and multi-row continuous furnaces, vacuum (low pressure) carburizing high pressure gas quenching furnaces, etc. Over the past decade, an important sign of the development of carburizing heat treatment technology is the application of sensing technology and computer technology in production. The process parameters of carburizing heat treatment, such as temperature, time, carbon potential, quenching process and action program are fully automatically controlled, and even according to the technical requirements of parts, material grades and characteristics, the system can automatically generate processes to achieve intelligent control. The characteristics of the domestic auto parts vacuum carburizing heat treatment production line are:

(1) The industrial computer monitors and automatically collects data on furnace temperature, carbon potential, and automatic line action programs.

(2) Automatic tracking and monitoring of the automatic line vacuum carburizing heat treatment process to realize the simulation and optimization of the carburizing process and the prediction of the carburizing quality of the parts.

(3) Real-time display and control of furnace temperature, carbon potential and action, automatic system fault diagnosis, display and alarm.

(4) The entire production process is automatically displayed, recorded, saved and archived online, and a traceable heat treatment quality management system is established. Production records from months or years ago can be queried as needed.

In the past 10 years, vacuum (low pressure) carburizing, high pressure gas quenching or oil quenching has been popularized and applied in the heat treatment of auto parts. Generally, vacuum (low pressure) carburizing is carried out at a low pressure of less than 2.7kPa, and the carburizing temperature is 880 to 980°C.

In order to meet the needs of higher vacuum carburizing, a new type of gear steel that can be carburized at a high temperature of 1000~1100°C to ensure the refinement of the structure is developed. Vacuum (low pressure) carburizing has the remarkable characteristics of greatly shortened process time, very little consumption of raw materials, small deformation of parts, good heat treatment quality, smooth surface of parts and no pollution. It is a clean and green heat treatment in the true sense.

Equipment selection: The RVN series vacuum carburizing furnace produced by SIMUWU is a high-quality product for the vacuum carburizing process of tools and molds. The good temperature control accuracy and temperature control uniformity ensure the effective progress of the vacuum carburizing process. SIMUWU specializes in the manufacture of vacuum furnaces, has more than ten years of relevant experience, and has a good reputation in the field of vacuum furnace manufacturing. The product line includes vacuum air quenching furnace, vacuum oil quenching furnace, vacuum brazing furnace, etc., which are widely sold in developed and developing countries.