The influence of material quality on the quality of truck helical gear has attracted more and more attention. The unstable material quality not only affects the heat treatment process control of truck helical gear It directly affects the fatigue life of truck helical gear. The quality requirements of truck helical gear materials abroad are very strict, which is mainly reflected in the control of hardenability and inclusions.
The hardenability of carburized steel has a significant impact on the strength, fatigue performance and heat treatment deformation of truck helical gear. Therefore, the hardenability bandwidth is generally specified as 6 ~ 8 HRC, while the physical quality can be controlled as 4-5 HRC. The narrow hardenability band can not only control the heat treatment deformation of truck helical gear in a small range, but also obtain an ideal hardness distribution curve. The limitation of inclusion level reduces the influence of inclusions on the fatigue life of truck helical gear. Therefore, foreign truck helical gear steel is generally refined outside the furnace in the smelting process to ensure the required performance.
At present, the truck helical gear steel of domestic automobile manufacturers with imported models is generally refined outside the furnace. The control of steel hardenability, inclusions and inclusions can basically reach the level of similar foreign products. FAW Group has used out of furnace refined zocrmnti and ordinary zocrmnti steel for comparative test. The results show that under the same conditions, out of furnace refining improves the fatigue life of truck helical gear by 1.5 times.