Method for manufacturing high-elongation nodular cast iron QT700-7 by using steel scraps

A ductile iron, high elongation technology, applied in the direction of improving process efficiency, etc., to achieve the effects of improving economic efficiency, low cost and simple production process

Inactive Publication Date: 2015-01-28
罗建华
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The production technology of high elongation nodular cast iron QT700-7 with scrap steel, while satisfying the tensile strength ≥ 700MPa, and the elongation ≥ 7%, is still blank at home and abroad

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0018] Example: Melt molten iron in a 5 ton intermediate frequency furnace.

[0019] The charge ratio is composed of 65% by weight of Q235 steel scrap and 35% of nodular iron return charge, wherein: the total amount of Q235 scrap steel added is 3250Kg, and the total amount of nodular iron return charge is 1750Kg.

[0020] Calculate the amount of 98.5% carburant added.

[0021] The total carbon content of the charge consisting of 65% by weight of Q235 steel scrap and 35% of ductile iron return charge is calculated according to the following formula.

[0022] The total carbon content of the charge = the weight percentage of Q235 steel scrap added (%) × the average carbon content of Q235 steel scrap (%) + the weight percentage of added ductile iron return charge (%) × the average carbon content of nodular iron return charge Value (%)=0.65%×0.146%+0.35%×3.50%=0.0949%+1.225%=1.3199%.

[0023] The carbon content lacking in the original molten iron in the furnace is calculated acco...

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PUM

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Abstract

The invention discloses a method for manufacturing high-elongation nodular cast iron QT700-7 by using steel scraps. Furnace burden comprises 60-85% of steel scrap Q235 and 15-40% of ductile cast iron foundry returns according to weight percentage; the method comprises the following steps: wire feeding type spheroidizing treatment, first wire feeding type inoculation treatment, second pour-over inoculation treatment and third stream inoculation treatment are carried out through alloying base iron in a furnace; casting, cooling, cleaning, tensile test and elongation rate calculation are carried out. Through the adoption of the method disclosed by the invention, as the steel scraps are adopted for production, the elongation rate reaches more than 7% while the tensile strength of the QT700 reaches more than 700 MPa; the problem that the elongation rate of the traditional nodular cast iron QT700-2 is low is solved; the requirement of high strength and high elongation rate of the nodular cast iron QT700 required for a high-requirement product is satisfied; a gap of the domestic and foreign technologies for manufacturing the high elongation nodular cast iron QT700-7 is filled; the cost is low; the economic benefits of manufacturing enterprises are obviously increased.

Description

technical field [0001] The invention relates to the technical field of metal material production, in particular to a production method for producing high-elongation nodular cast iron QT700-7 by using scrap steel. Background technique [0002] Existing ductile iron QT700-2, national standard GB / T 1348-2009 "Ductile iron castings", Japanese standard FCD700-2, British standard BS700-2, German DIN standard GGG70, French NF standard EN-GJS-700-2 It is stipulated that the tensile strength is ≥700MPa and the elongation is ≥2%. As long as the product meets these two technical indicators at the same time, it is qualified; The elongation rate is 1% higher than the national standards mentioned above. However, for high-demand products that require high strength and high toughness at the same time, when the tensile strength is ≥700MPa and the elongation is ≥2%, although the strength meets the requirements, the toughness is low and easy to Fracture is far from meeting the requirements of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C1/10C22C33/08C22C37/04
CPCY02P10/20
Inventor 罗建华
Owner 罗建华
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