The fracture splitting method is being increasingly used for manufacturing connecting rods that are made of the powder forging material, high-carbon steel, etc., which are comparatively easy to fracture, in order to improve the accuracy and productivity. In this paper, a microalloyed high carbon steel used for fracture splitting connecting rod is developed by the process “EAF-EBT-LF-CC-CR”. The steel microstructure, nonmetallic inclusions, precipitated phases, mechanical property and fracture surfaces are investigated by microscope, SEM and TEM. The results show that the steel is constituted of pearlite and a small mount of ferrite, the nonmetallic inclusions in the steel include MnS, Al-rich (taken to be Al2O3) and Al-Ca-rich (taken to be CaO-Al2O3) particles. The precipitations mainly are VC, VN, (Mn, Cu)S, etc. these precipitations are beneficial to fine the pearlite group, short lamellar spacing of pearlite and improve the strengthening of the microalloyed high carbon steel. The tensile tests indicate that the microalloyed high carbon steel has high yield strength, ultimate tensile strength (UTS), but low elongation and contraction of area. It is required for heavier loads, higher performance of automobile engine and less distortion on fracture splitting. The fracture surface of connecting rod shows distinct brittle fracture character and it is beneficial to improve fracture splitting performance.
509 Investigation of Improved Fracture Splitting Method for Aluminum Alloy Die Casting Connecting Rod
