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Austenic cast iron with low Al and Ni content and medium Mn content and its production process

A process method and austenitic technology, which are applied to low-aluminum, low-nickel, medium-manganese, and austenitic cast iron and its technological fields, can solve the problems of easy oxidation, deteriorate alloy processing performance, affect casting quality, etc., and achieve low adding amount and reducing Inclusion of casting defects and good thermal stability

Inactive Publication Date: 2004-09-08
DONGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, if too many aluminum ingots are added to the furnace, this type of alloy is easily oxidized at a high temperature of 1500 ° C, resulting in slag inclusions, forming hard spots, deteriorating the processing performance of the alloy, and causing graphite to float, which affects the quality of the casting.

Method used

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  • Austenic cast iron with low Al and Ni content and medium Mn content and its production process
  • Austenic cast iron with low Al and Ni content and medium Mn content and its production process
  • Austenic cast iron with low Al and Ni content and medium Mn content and its production process

Examples

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Effect test

Embodiment 1

[0029] Melting of low nickel, medium manganese austenitic cast iron. The chemical composition is: C3.70%, Si2.6%, Ni1.5%, Mn10.0%, Cu2.5%. Charges include ordinary pig iron, steel scrap (shavings), recycled charge, high-carbon ferromanganese, electrolytic nickel, 75 ferrosilicon and aluminum wire. Use a power frequency electric furnace to melt the charge. Raise the temperature to 1420°C and leave the oven. Add 0.7% 75% ferrosilicon and 0.25% aluminum wire into the ladle and stir evenly. Cast standard bending test bars and cylindrical castings of 130 (outer diameter) × 68 (inner diameter) × 200 (height) mm with sand molds. Cool to below 700°C to shake out sand and cool. As-cast metallographic microstructure see figure 1 . Type A graphite flakes are evenly distributed on the austenite matrix. The carbides are larger in size, in the shape of curved sheets, distributed between the austenite grains, and the amount is about 6%. It shows that the amount of inoculation in the ...

Embodiment 2

[0036] Melting of low nickel, medium manganese austenitic cast iron. The aluminum content is 0.3%, and the other chemical components and melting process are the same as in Example 1. Add 0.7% 75 ferrosilicon and 0.4% aluminum wire in the bag. As-cast metallographic structure (see figure 2 ) consists of fine A-type graphite flakes, austenite matrix and fine granular carbides. The number of carbides is 2.5%. It shows that increasing the amount of aluminum added in the ladle can effectively strengthen the inoculation effect and greatly reduce the number of carbides. Table 2 lists the alloy mechanical properties, thermal expansion coefficient and austenite thermal stability. The coefficient of thermal expansion is 18×10 -6 / °C, equivalent to ISO2896. The tensile strength and hardness also meet the requirements of ISO2896 (Edited by Ge Chenguang, Zhang Yunhua, and Zhu Wengao: The latest international casting standards. Compiled by the Secretariat of the National Casting Stan...

Embodiment 3

[0041] Melting of low nickel, medium manganese austenitic cast iron. The chemical composition is: C3.3%, Si2.5%, Mn8.3%, Ni4.0%, Cu2.7%, Al0.3%. Melting process is the same as embodiment 1. First add 05% 75 ferrosilicon into the ladle. Then, rush into 0.5% aluminum wire and 75 ferrosilicon with the molten iron flow for instant inoculation. Cast standard bending test bars and cylindrical castings of 130 (outer diameter) × 68 (inner diameter) × 200 (height) mm with sand molds. Cool to below 700°C to shake out sand and air cool. The fracture of the casting is thin, dense, free of inclusions and non-magnetic. As-cast metallographic structure (see image 3 ) consists of fine curved A-type graphite flakes, an austenite matrix and fine granular carbides. The amount of carbides is less than 1.5%, evenly distributed on the matrix, meeting the requirements of engine piston rings. Table 3 gives the alloy mechanical properties and thermal stability. This cast iron was kept at 580°...

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Abstract

The present invention features that into austenic cast iron with low Al and Ni content and medium Mn content, 75 ferro-silicon alloy and / or Al is added to obtain metallographic structure comprising type-A graphite, austenic base and homogeneously distributed granular carbide of quantity not less than 1.5 %. The technological process includes melting charging material first in electric furnace or cupola furnace with tapping temperature over 1400 deg.c, adding 75 ferro-silicon alloy in iron ladle, and subsequent adding 75 ferro-silicon alloy and / or Al wire. The austenic cast iron of the present invention has the chemical composition of: C3.0-4.0 wt%, Si 2.0-3.0 wt%, Mn 8.0-10.0 wt%, Ni 1.0-4.0 wt%, Cu less than 3.0 wt% and Al not more than 0.3 wt%. It is suitable for use in electric equipment parts, engine piston ring and cylinder sleeve with operating temperature lower than 500 deg.c.

Description

technical field [0001] The invention relates to an austenitic cast iron and a process method thereof. More precisely, it relates to a low-aluminum and low-nickel medium-manganese austenitic cast iron and a process method thereof. Background technique [0002] High-alloy austenitic cast iron has good high-temperature mechanical properties and corrosion resistance, and can be used to manufacture engine supercharger parts and exhaust pipes. This alloy is non-magnetic and suitable for the production of various electrical equipment parts. Its expansion coefficient is close to that of aluminum-silicon piston alloy, and it is the preferred material for engine piston rings and cylinder liners. Austenitic cast iron is roughly divided into high nickel series and high manganese series. Commonly used high-nickel austenitic cast irons contain nickel in the range of 13.5-36% (ASTM A435-84. BS 3468: 1986. China Mechanical Engineering Society Casting Society Edited: Casting Handbook Volu...

Claims

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Application Information

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IPC IPC(8): C22C37/10
Inventor 王汝耀鲁薇华杨涤心杨留栓
Owner DONGHUA UNIV
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