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 number | Connecting rod manufacturer | Connecting rod forging mass, kg | Billet heating mode | Blank making method | Die forging equipment capacity, Mn | Final heat treatment equipment configuration |
| 1 | Shangchai Co., Ltd | 4，4.8，5.9 | IF penetration | Cross wedge rolling | 40 | Chain casting furnace |
| 2 | FAW forging plant | 2.02 | IF penetration | Roll forging | 31.5 | Pusher furnace |
| 3 | Second Automobile Forging Plant | 2.52 | IF penetration | Roll forging | 25 | Pusher furnace |
| 4 | NAC forging plant | 1.22 | IF penetration | Roll forging | 25 | Pusher furnace |
| 5 | SAIC die forging plant | 1.2 | IF penetration | Roll forging | 25 | Chain casting furnace |
| 6 | Lansing United Forge | 4.0 | IF penetration | Roll forging | 25 | Pusher furnace |
| 7 | Skoda automobile factory | 0.95 | IF penetration | Cross wedge rolling | 25 | Pusher 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.