1.Pearlite malleable cast iron is the main material of automobile connecting rod.
Its chemical composition is roughly 2.6%c, 1.4%si, 0.42%mn, and the rest is Fe. Rare earth magnesium nodular cast iron is also suitable for manufacturing automobile connecting rods. However, the hardness of the cast automobile connecting rod should be between hb210 and 250, the elongation should be 2%, and the bending fatigue strength should be 300 ~ 350n / m2.
Nodular cast iron automobile connecting rod is used in some diesel engine connecting rods (such as S195, 120, 125). The cost is low, but it is prone to structural defects such as anti white and micro shrinkage. The overall impact resistance of automobile connecting rod is not high. In general, cast iron connecting rod is less and less used in automobile diesel engine.
2.Aluminum alloy connecting rod
High strength can be obtained by infiltrating short fiber into aluminum alloy connecting rod. The mass of aluminum is about 1 / 3 of that of steel. Therefore, under the same performance requirements, its mass decreases by about 30%. Fiber materials include alumina (AI2O3) and silicon carbide (SIC). The reinforcing fiber shall be bonded with appropriate adhesive, prefabricated and formed. After being put into the die, the aluminum solution shall be poured into the die to immediately pressurize, so that the aluminum solution can penetrate into the gap of the preform, or it shall be manufactured by means of die forging blank after high-pressure solidification casting. Through the optimization design of automobile connecting rod big end, the swing mass may be reduced by about 90% when the rotating mass remains unchanged.
The fiber reinforced Al Li alloy based composite casting automobile connecting rod developed by Chrysler and DuPont has light weight, good strength and small expansion coefficient, which is very beneficial to improve engine efficiency and fuel economy. The number of test cycles exceeds ten million. However, the cast aluminum alloy connecting rod is mainly used for small parts such as air compressors, motorcycles and various compressors, with a large amount. The die forging and squeeze casting after metal mold casting can meet the use requirements.