Exhaust manifold

The exhaust manifold is connected to the engine block, and the exhaust of each cylinder is collected and introduced into the exhaust manifold with divergent pipes. The main requirement for it is to minimize the exhaust resistance and avoid mutual interference between the cylinders. When the exhaust gas is excessively concentrated, mutual interference occurs between the cylinders, that is, when a certain cylinder is exhausted, it is just the exhaust gas that is not discharged from other cylinders. In this way, the resistance of the exhaust gas is increased, thereby reducing the output of the engine. The solution is to separate the exhaust of each cylinder as much as possible, one branch per cylinder, or one branch of two cylinders, and make each branch as long as possible and independently form to reduce the gas interaction between different tubes.

Characteristics and requirements of exhaust manifold materials

Good high temperature oxidation resistance

The exhaust manifold works for a long time under high temperature cyclic alternating state, and the oxidation resistance of the material at high temperature directly affects the service life of the exhaust manifold. Ordinary cast iron obviously cannot meet the requirements, and it is necessary to add alloying elements to the material to improve the high-temperature oxidation resistance of the material.

Stable microstructure

The material should be as phase-independent as possible or minimize phase change from room temperature to operating temperature. Because the phase change will cause a change in volume, causing internal stress or deformation, affecting the product's performance and life. Therefore, the matrix material is preferably a stable ferrite or austenite structure. The failure mode of cast iron parts working under high temperature conditions is mainly characterized by corrosion under high temperature conditions. After oxidation of the constituent phases in the structure (such as graphite carbon), the volume of the oxide is larger than the original volume, causing irreversible expansion of the casting.

Compared with flake, wormlike, and spheroidal graphite forms, spheroidal graphite has the best high temperature resistance of cast iron because the flake graphite grows during the solidification process, and the eutectic solidification ends. The graphite in the eutectic group constitutes a continuous branching stereoscopic shape. At high temperature, when oxygen intrudes into the interior of the metal, the graphite is oxidized to form a microscopic channel to accelerate the oxidation process. When the spheroidal graphite nucleus grows up to a certain size, it is surrounded by the matrix and exists as an isolated sphere. After the graphite sphere is oxidized, no channel is formed, thus weakening the further oxidation, so the high temperature oxidation resistance of the ductile iron It is better than other forms of graphite, and the pores after oxidation have a lower effect on the high temperature of cast iron than other forms of graphite, and the viscose ink is between the two.

Small thermal expansion coefficient

The small coefficient of thermal expansion helps to reduce the thermal stress and thermal deformation of the exhaust manifold, which is beneficial to improve the serviceability and service life of the product.

Excellent high temperature strength

Must meet the necessary strength requirements of the product when used at high temperatures.

Good process performance and low cost

There are many types of heat-resistant and high-temperature resistant metal materials, but due to the complicated shape of the exhaust manifold, the materials used to manufacture the exhaust manifold must have good processability, and the cost must meet the needs of mass production in the automotive industry.

The engine parts brand that we have as following:

Cummins, Perkins, Mitsubishi, Caterpillar,VOLVO, Komatsu,Isuzu, Yanmar,Hitachi, DEUTZ, Yuchai, Shangchai, Weichai and so on.