From the above analysis of the service conditions and failure forms of gears, it is proposed that the performance requirements of heavy truck gear materials are: high bending fatigue strength; High contact fatigue strength and wear resistance; High strength and toughness. In addition, it is also required to have good heat treatment process performance. The required performance of heavy-duty vehicle gear materials is mainly high fatigue strength, and the factors affecting the failure and fatigue strength of heavy-duty vehicle carburized gears mainly include core hardness, effective hardening layer depth, core metallographic structure, surface hardness and surface residual stress distribution, gear manufacturing accuracy and so on. Therefore, according to the carburization requirements of heavy truck gears At present, heavy truck gears are made of relatively mature alloy carburized steel.
The following factors are mainly considered when selecting steel for carburized gear of heavy truck:
(l) The hardenability of steel should ensure that the tooth surface and center of the gear get the specified hardness after carburizing and quenching, so as to meet the service requirements of the gear. At the same time, it is also hoped that the hardenability of steel is narrow to ensure that the deformation range of the gear after heat treatment is small.
(2) The steel shall be essentially fine grain steel to ensure that the austenite grain does not grow during high-temperature carburizing. Direct quenching after carburizing shall be adopted as far as possible. For quenching, it should be noted that the quenching process and quenching oil temperature have a great influence on the change of gear shape and size.
(3) Good cold working performance.