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ADI (Austempered Ductile Iron) piece with high toughness and high strength and manufacturing method thereof

A manufacturing method and high-strength technology, applied in the direction of improving process efficiency, etc., can solve problems such as low purity of sulfur content, affecting the quality of casting blanks, and serious cooling of molten iron, so as to reduce the amount of gas and inclusions, and achieve high strength. , the effect of reducing processing costs

Inactive Publication Date: 2010-11-03
WUHAN TEXTILE UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the production of ADI is mainly based on experience to explore the chemical composition of castings and the parameters of austempering heat treatment. The smelted molten iron is generally directly subjected to spheroidizing inoculation treatment, often due to the high sulfur content in the molten iron and the low purity of the molten iron. However, it affects the quality of casting blanks; the desulfurization treatment is carried out by shaking the ladle outside the furnace, the device is complicated, the temperature of molten iron is seriously lowered (over 100°C), and the cost is high, so it is difficult to popularize and apply in production; the usual austempering heat treatment process makes The resulting ADI parts are difficult to meet the requirements of high toughness while meeting high strength

Method used

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  • ADI (Austempered Ductile Iron) piece with high toughness and high strength and manufacturing method thereof
  • ADI (Austempered Ductile Iron) piece with high toughness and high strength and manufacturing method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0020] (1) Clay sand molding is adopted (in this embodiment, clay green sand molding, furan resin sand core, or resin sand molding is used). It is required to have high mold compactness, mold sand moisture ≤ 5%, air permeability ≥ 100, wet compressive strength ≥ 0.11MPa, and design a suitable casting process according to the casting structure.

[0021] (2) Using nodular iron pig iron, nodular iron return charge, scrap steel and Cu, Ni, Mo alloy materials as the metal charge, the mass percentage content of each element in the charge is: C 3.90-3.95%, Si 1.1-1.3%, Mn 0.2-0.3%, P≤0.035%, S≤0.025%, Mo 0.2-0.25%, Cu 0.6-0.8%, Ni 0.5-0.8%, and the balance is Fe. Using intermediate frequency electric furnace for smelting, first add nodular iron pig iron, nodular iron return material and scrap steel into the furnace, after it is melted, then add Cu, Ni, Mo alloy materials, after all metal furnace materials are melted, detect C and Si in the molten iron Whether the content is satisfie...

Embodiment 2

[0026] The method for producing ADI parts in this embodiment is the same as in Example 1 (including molding, batching, smelting, molten iron pretreatment, spheroidizing inoculation treatment, austenitization, etc.), the difference is that the molten iron after smelting is heated to 1460 °C, the temperature of molten iron after purification treatment is raised to 1510 °C, and the austempering temperature is set to 360 °C. The mass percentages of the elements in the final ADI parts are: C 3.65%-3.75%, Si 2.55%-2.7%, Mn0.2%-0.25%, P 0.015%-0.025%, S 0.008%-0.012 %, Mo 0.23% to 0.25%, Cu 0.65% to 0.75%, Ni 0.6% to 0.75%, and the balance is Fe. Adopt the method identical with embodiment 1 to test the elongation, impact toughness and tensile strength of ADI piece, its elongation is 13~14%, and impact toughness is 128~135J / cm 2 , The tensile strength is 1020~1050MPa.

Embodiment 3

[0028] The method for producing ADI parts in this embodiment is the same as in Example 1 (including molding, batching, smelting, molten iron pretreatment, spheroidizing inoculation treatment, austenitization, etc.), the difference is that the molten iron after smelting is heated to 1480 °C, the temperature of molten iron after purification treatment is raised to 1520 °C, and the austempering temperature is set to 350 °C. The mass percentages of the elements in the final ADI parts are: C 3.7%-3.8%, Si 2.5%-2.6%, Mn 0.25%-0.3%, P≤0.03%, S≤0.012%, Mo 0.22%~ 0.25%, Cu 0.75% to 0.8%, Ni 0.5% to 0.7%, and the balance is Fe. Adopt the method identical with embodiment 1 to test the elongation, impact toughness and tensile strength of ADI parts, its elongation is 12.5~13.5%, and impact toughness is 125~130J / cm 2 , The tensile strength is 1050~1080MPa.

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Abstract

The invention discloses an ADI piece with high toughness and high strength and a manufacturing method thereof. The ADI piece comprises the following elements by mass percent: 3.6% to 3.9% of C, 2.5% to 2.7% of Si, 0.2% to 0.3% of Mn, smaller than or equal to 0.03% of P, smaller than or equal to 0.012% of S, 0.2% to 0.25% of Mo, 0.6% to 0.8% of Cu, 0.5% to 0.8% of Ni and the balance of Fe. The ADI piece has the elongation of 12.5% to 14.5%, the impact toughness of 125 to 140J / cm2, and the tensile strength of 990 to 1080MPa. The manufacturing method comprises the steps of: smelting burden in an intermediate frequency electric furnace; pretreating melted iron for desulfuration and dephosphorization and then pouring into a casting mould to obtain a raw casting; preserving the temperature of 905 DEG C to 915 DEG C for 1.5 to 2 hours for austenitizing the raw casting; quickly quenching in a salt bath at 350 DEG C to 370 DEG C for isothermal quenching for 1 to 1.5 hours; cooling and washing to obtain the ADI piece. The ADI piece of the invention has high elongation, high impact toughness and higher tensile strength. In the pretreatment of melted iron, no new equipment is added. The technological parameter is reasonably designed and the manufacturing cost is low.

Description

technical field [0001] The invention relates to a high-toughness and high-strength ADI (austempering ductile iron) piece and a manufacturing method thereof. Background technique [0002] The Austempered Ductile Iron (ADI) new material developed in the 1970s, due to its high strength, high wear resistance and certain toughness, is widely used in automobiles, agricultural machinery, building materials, railways, general machinery, etc. It has been applied in many fields. Some industrially developed countries (such as the United States, Japan, the European Union, etc.) have successively formulated ADI standards, such as the mechanical performance indicators (tensile strength MPa / elongation% / impact toughness J / cm2) in the American ADI standard (ASTM897M-03) 2 ) is: 900 / 9 / 100, 1050 / 7 / 80, 1200 / 4 / 60, 1400 / 2 / 35, 1600 / 1 / 20. How to improve the toughness of ADI parts while maintaining high strength is a difficult problem. [0003] Producing high-quality nodular iron casting blanks a...

Claims

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Application Information

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IPC IPC(8): C22C37/10C22C33/08B22D1/00C21D6/00C21D1/20
CPCY02P10/20
Inventor 龚文邦向纲玉
Owner WUHAN TEXTILE UNIV
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