What are the cast iron casting
In the production of cast iron, cast iron pieces often can produce different kinds of casting defects, how to prevent these defects, has been a matter of concern to the casting factory.
This paper introduces the author of some of the understanding and practice experience in this field.
1 stomata characteristics: porosity in the casting is within the castings, appearance or near appearance in the size of the lubrication hole.
Often with oxidation of hole wall color, because the origin of gas and composition for different reasons, stomatal form also each are not identical, invasive porosity, ceding porosity, subcutaneous blowhole, etc.
More than 1 to separate sex porosity the stomata and wandering, generally located in the casting exterior often with group of pouring castings are mostly found to have.
The stomatal first because in the process of smelting, metal absorption of gas before condensation separated, failed to appear on the then constitute the many distractions of the small hole in the casting.
To prevent 】
Choose clean dry furnace charge, constraint air content more burden.
Guarantee & other;
Three dry & throughout;
: that is, the iron tank, taphole, cross the bridge to completely dry.
Ladle to drying, it is best to use before liquid iron and iron liquid package, be sure to put YanGaiJi in liquid iron appearance.
All kinds of additives (
Nodulizing agent, inoculant, YanGaiJi)
A tramp to dry, high humidity, would use after drying.
2 invasive stomatal this small number of pores, scale is larger, more happened in casting parts outside appearance, a pear shape or round ball.
First because the casting or sand core gas into liquid metal has not been able to escape.
To prevent 】
Cutting gas evolution: the manipulation of the sand and core sand found material content of gas, water content of green sand is not too high, the modelling and repair the mould release agent and water dosage shoulds not be too much.
Sand core to ensure the drying, drying after the sand core deposit shoulds not be too long, use the day before the use of sand core oven drying, with sand control core absorption of moisture, do not use be affected with damp be affected with damp, cold rusty iron and core support, etc.
Improve sand permeability, choose suitable type of empty compactness, reasonable arrangement of the blow hole azimuth and exhaust, guarantee the sand core ventilation channel dredging.
Appropriate progress pouring temperature, porosity and exhaust all riser, etc. , to facilitate the gas buoyancy of liquid metal into the drain.
3 subcutaneous blowhole this hole first appeared in the surface layer of casting subcutaneous 2-3 mm, about 1 ~ 3 mm in diameter.
And the number is more, castings after heat treatment or rough machining to remove skin, will clearly show it.
To prevent 】
Appropriate progress, pouring temperature, strict control of various additives in quantity, shorten the casting time as much as possible.
Inoculant amount the best control in (
The mass fraction)
4% ~ 0.
Inoculants 6%, together we will strictly control the mass fraction of A1, w (
On the high side is simple and cavity surface moisture response: 2 al + 3 h2o = Al2O3 + 3 h2 & uarr;
Normally, inoculant should not exceed 1 Al content.
Avoid iron melt oxidation, appropriate adding relay coke, strictly control into the air.
Above hope can better for you to take a iron quality improvement, if you want to know more about the relevant details, welcome to the company.
Nanjing nanjing foundry co. , LTD. Address: jiangsu province road 200, new district wu bonanza hotline: 020-86
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