Method for preparing ductile iron exhaust manifold

Abstract

The invention relates to a preparation method for ductile iron exhaust manifold, the ductile iron mainly comprises iron, phosphorous, sulfur, magnesium, antimony, tin, boron, aluminum, chromium, nickel, lead, titanium, vanadium, manganese, copper, molybdenum, carbon and silicon alloy elements; wherein, according to weight content, the manganese is 0.10 to 0.20%, the copper is less than 0.20%, the molybdenum is 0.80% plus or minus 0.03%, the carbon is less than 3.35%, and the silicon is less than 3.65 as well as 0.15% plus or minus 0.05% metal-stream inoculant. The exhaust manifold is cast and formed by a casting device comprising a sprue, a water inlet, a cross gate and a feeder head; wherein, the water inlet is a pipe string body; a groove inclined outwards is arranged on a pipe wall near the position near the joint of the water inlet and the casting pieces; an included angle is formed between the tail end of the water inlet and the cross gate. The preparation method for ductile iron exhaust manifold has the advantages of increasing thickness of joint of water inlet and the casting pieces body, improving connecting strength between the casting pieces and the water inlet, and effectively reducing damage to the casting pieces when the stream is removed.

Description

1. Technical field [0001] The invention relates to an exhaust manifold for an engine, in particular to a material for an exhaust manifold of Si Mo ductile iron for an engine and its preparation, and a preparation method for an exhaust manifold of ductile iron using this material to prepare an exhaust manifold . 2. Background technology [0002] With the development of technology in the automotive industry, the technical requirements for auto parts are getting higher and higher. The exhaust pipe used for the engine has also developed from stainless steel products to heat-resistant cast iron. The result of this conversion is to reduce the cost of materials but at the same time increase the technical requirements for the production and preparation process. The main technical requirements of the production and preparation process include: heat-resistant temperature at 870°C, no deformation (deformation < 0.5mm) under alternating hot and cold conditions, and thermal fatigue ...

AI Technical Summary

Problems solved by technology

[0006] First of all, by reducing the pearlite content in the metallographic structure of ductile iron, that is, controlling the pearlite content to less than 10%, the performance of the material of the ductile iron exhaust manifold is improved, so that the fatigue resistance of the ductile iron exhaust manifold is good. Under the conditions of alternating hot and cold, it has the effect of no deformation; secondly, improve the structure of the pouring device suitable for this material, overcome the shrinkage and damage defects during the casting process of this kind of ductile iron, and improve the quality of the exhaust manifold. And can meet mass production requirements

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