Importance of heat treatment process for forging quenched and tempered steel connecting rod

The product quality of quenched and tempered steel connecting rod is mainly determined by the technical parameters such as quenched and tempered hardness, quenching hardness, metallographic structure and mechanical properties. In order to ensure the safety of use, the connecting rod must be quenched and tempered.

The forging of quenched and tempered steel connecting rod requires a special forging production line and is equipped with a continuous heat treatment furnace for the final heat treatment of the connecting rod. Table shows the configuration of forging and heat treatment equipment of several representative manufacturers.

Serial numberConnecting rod manufacturerConnecting rod forging mass, kgBillet heating modeBlank making methodDie forging equipment capacity, MnFinal heat treatment equipment configuration
1Shangchai Co., Ltd4,4.8,5.9IF penetrationCross wedge rolling40Chain casting furnace
2FAW forging plant2.02IF penetrationRoll forging31.5Pusher furnace
3Second Automobile Forging Plant2.52IF penetrationRoll forging25Pusher furnace
4NAC forging plant1.22IF penetrationRoll forging25Pusher furnace
5SAIC die forging plant1.2IF penetrationRoll forging25Chain casting furnace
6Lansing United Forge4.0IF penetrationRoll forging25Pusher furnace
7Skoda automobile factory0.95IF penetrationCross wedge rolling25Pusher furnace

The connecting rod bears complex tension and compression alternating load. If the material and hot working process are out of control, it will leave internal defects to the connecting rod. During the operation of the engine, it is very easy to cause the connecting rod fracture and failure, which will not only destroy the whole machine, but also endanger personal safety. Therefore, there are high requirements for material and hot working process control. Material defects, such as shrinkage cavity residue, overburning, forging crack, composition segregation, inclusions, etc., can only be found through destructive inspection; Mechanical properties, chemical composition and metallographic structure can only be selected for spot check. Therefore, it is of great significance to ensure the service performance of connecting rods and the reliable and safe operation of the whole machine by keeping the materials of connecting rods in a controlled state and the hot working process under strict control.