Cast aluminum-silicon alloy for engine cylinder head and heat treatment process

Abstract

The invention relates to a cast aluminum-silicon alloy for an engine cylinder head and a heat treatment process. The alloy comprises the following chemical ingredients in percentage by weight: 5.0 to 7.0 percent of Si, 3.0 to 4.0 percent of Cu, 0.2 to 0.4 percent of Mg, 0.1 to 0.3 percent of Mn, 0.10 to 0.20 percent of Zr, 0.15 to 0.25 percent of Ti, 0.01 to 0.05 percent of B, 0.02 to 0.09 percent of Sr, 0.1 to 0.3 percent of rare earth (RE), less then 0.3 percent of Fe and the balance Al, wherein the rare earth (RE) adopts mixed rare earth. The heat treatment process comprises the following steps: carrying out primary solution at a temperature between 490 DEG C and 505 DEG C, and carrying out heat insulation for 4 to 6h; carrying out secondary solution at a temperature between 510 DEG C and 525 DEG C, carrying out heat insulation for 6 to 10h, and carrying out quenching by hot water of 60 to 80 DEG C; and carrying out aging treatment with parameters of the aging temperature being 155to 165 DEG C and the heat insulation time being 5 to 9h, and carrying out cooling in the air. All alloy elements of the cast aluminum-silicon alloy provided by the invention are reasonably matched, good mechanical performance is realized, at a normal temperature, the tensile strength reaches 325 to 355MPa, the tensile stretch is 2.5 to 5.5 percent, at a high temperature of 250 DEG C, the tensile strength reaches 240 to 270MPa, and the tensile stretch is 3.0 to 5.5 percent, after the heating processing technology, the heat resistance performance of the alloy is improved, and the casting defect is reduced.

Description

technical field [0001] The invention relates to the technical field of cast aluminum alloy and heat treatment, in particular to a cast aluminum-silicon alloy for an engine cylinder head and a heat treatment process. Background technique [0002] Among aluminum alloys, aluminum-silicon alloys have excellent casting properties (such as low fluidity, good air tightness, small shrinkage, and low tendency to thermal cracking), good specific strength, corrosion resistance, weldability, and low expansion. It has been widely used due to its advantages. In particular, some large and complex aluminum castings are made of aluminum-silicon alloys, such as engine blocks, cylinder heads, and gearbox housings. The engine cylinder head is a typical complex aluminum casting, which integrates complex oil, water and gas structural units in its structure. Moreover, the engine cylinder head, piston, and cylinder together form the combustion chamber of the engine, and the working conditions are...

AI Technical Summary

Problems solved by technology

Therefore, when the mechanical load or thermal load of aluminum alloy castings increases, these aluminum-silicon alloys cannot meet the requirements of use.

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