2. Quenching and tempering shall be carried out after processing, and the hardness requirements shall be given by the design department. Quenching is to ensure that the finished product has certain hardness and wear resistance. Tempering is to eliminate the internal stress caused by quenching structure transformation.
Main damage forms
The main damage forms of connecting rod are fatigue fracture and excessive deformation. Usually, the fatigue fracture site is three high stress areas on the connecting rod. The working conditions of the connecting rod require that the connecting rod has high strength and fatigue resistance; It also needs sufficient rigidity and toughness. In the traditional processing technology of connecting rod, the material is generally quenched and tempered steel such as 45 steel, 40Cr or 40MnB, which has high hardness. Therefore, new connecting rod materials produced by German automobile enterprises, such as C70S6 high-carbon microalloyed non-quenched and tempered steel, SPLITASCO series forged steel, FRACTIM forged steel, S53CV-FS forged steel, etc. (All the above are German din standards). Although alloy steel has high strength, it is sensitive to stress concentration. Therefore, strict requirements should be put forward for connecting rod shape and excessive fillet, and attention should also be paid to surface processing quality to improve fatigue strength, otherwise the application of high-strength alloy steel will not achieve the expected results.