High creep rate vermicular graphite cast iron for internal combustion engine cylinder block and cylinder head and its manufacturing method

Abstract

The invention relates to vermicular graphite cast iron with a high rate of vermiculation of a combustion motor cylinder body and a cylinder cover and a preparation method, and belongs to the field of casting method. The vermicular graphite cast iron with the high rate of the vermiculation of the combustion motor cylinder body and the cylinder cover and the preparation method are characterized in that the vermicular graphite cast iron with the high rate of the vermiculation comprises the following chemical components: 3.4%-3.7% of carbon, 2.0%-2.5% of silicon, 0.5%-0.8% of manganese, 0%-0.08% of phosphorus and 0%-0.04% of sulphur, with the balance being iron. In a microscopic structure, a pearlite area accounts for 50%-70%, a ferrite area accounts for 30%-50%. The mechanical properties are as follows: strength of extension sigma b is more than or equal to 320 MPa to 400 MPa, ductility delta is 1%-4%, and hardness HB is 160-230. Due to the fact that molten iron component is near an eutectic point, scope of crystallization is narrow, liquidity is good, casting performance is good, the tendency of a casting shrinkage cavity and shrinkage porosity is little, a wholesome cylinder cover cast and wholesome cylinder body cast are easy to obtain, the service lives of the cylinder cover and the cylinder body are prolonged, certainly, the vermicular graphite cast iron with the high rate of the vermiculation of the combustion motor cylinder body and the cylinder cover and the preparation method play a pivotal role of the performance of improving the combustion motor and prolonging the service life of the combustion motor.

Description

technical field [0001] The invention relates to a high vermicular graphite cast iron for an internal combustion engine cylinder block and a cylinder head and a manufacturing method thereof, belonging to the field of casting methods. Background technique [0002] In the prior art, high-strength gray cast iron materials such as gray cast iron HT250 and gray cast iron HT300 are mostly used in the casting and production of cylinder blocks and cylinder heads of internal combustion engines. In actual use, gray iron cylinder heads and cylinder blocks often have thermal fatigue cracks, which is determined by the characteristics of gray cast iron. Since the elongation of gray iron is almost zero, the thermal shock resistance is poor. The tensile strength of vermicular graphite cast iron is higher than that of general high-strength gray cast iron, it has a certain elongation, and its fatigue resistance is better than that of general high-strength gray cast iron. However, due to the d...

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Problems solved by technology

However, due to the difficulty in the casting production of compacted graphite cast iron, although some foundry manufacturers produce compacted graphite cast iron, it is difficult to stably obtain compacted graphite cast iron with high creeping rate

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