Study on laser 3-D printing process of automotive engine connecting rods

In order to study the manufacturing process of laser 3-D printing for automobile engine connecting rods, by means of theoretical analysis and experimental verification, 3-D model of a connecting rod was established and slicing was done. By S-type scanning and contour offset scanning, two machining paths of connecting rods were planned. Alloy powders based on iron and the corresponding technological parameters were selected to carry out the rod print test in a laser 3-D printing system. It took 4min30s~4min56s to scanning a single layer and it took 4h20min totally. The results show that the metallographic structure at the bottom of the forming zone of the connecting rod is mainly columnar crystal and dendritic crystal. The middle and upper part are small equiaxed crystal. Interlayer is dense and good metallurgical bonding had been formed. The microhardness of the formed connecting rod is 450HV~490HV, yield strength is 754MPa, tensile strength is 1189MPa, and elongation rate was 9%. Compared to forging, powder forging manufacturing processes, laser 3-D printing forming reduces tooling costs and shortens the production preparation time. Its mechanical properties, such as yield strength and tensile strength, exceed those of steel forging links. Compared with foreign powder forged connecting rod, the difference is not very big. The process can meet the requirements of connecting rod blank making.