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Method for producing mandrel by utilizing 28NiCrMoV steel as raw material

A technology of raw materials and mandrels, applied in the direction of metal rolling, manufacturing tools, mandrels, etc., can solve the problems of difficult guarantee of transverse impact toughness and high production cost, and achieve the elimination of flaky pearlite, uniform structure and composition, and cooling speed Fast, grain-refining effect

Active Publication Date: 2010-12-08
HENAN ZHONGYUAN SPECIAL STEEL EQUIP MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The most commonly used mandrel material at home and abroad is H13 steel, but its transverse impact toughness is not easy to guarantee, and the production cost is too high

Method used

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  • Method for producing mandrel by utilizing 28NiCrMoV steel as raw material
  • Method for producing mandrel by utilizing 28NiCrMoV steel as raw material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] Example 1: The mandrel steel type is 28NiCrMoV10, which is formed by material selection-refining-forging-rough machining-heat treatment-finishing. After material selection, the EAF+LF / VD refining method is adopted, and the furnace charge is made of secondary or above Composed of steel scrap, return material head, high-quality steelmaking pig iron, sponge iron, etc., tap after EAF oxidation, pre-deoxidize and partially alloy in the ladle, carry out LF / VD argon blowing refining, weakly stir before tapping, and use after tapping and calming Argon protection pouring, hot forging after stripping the steel ingot, controlled chemical composition during the refining process: C = 0.26-0.32%, Si = 0.30-0.50%, Mn = 0.20-0.40%, Ni = 2.30-2.60%, Cr =0.70~0.90%, Mo=0.55~0.70%, V=0.25~0.32%, S≤0.005%, P≤0.013%; then heated in the bottom gas furnace, the temperature of the heating furnace is 1150℃, the temperature of the billet is allowed 20°C lower than the furnace temperature to ensu...

Embodiment 2

[0014] Example 2: The mandrel steel type is 28NiCrMoV10, which is formed by material selection-refining-forging-rough machining-heat treatment-finishing. After material selection, the EAF+LF / VD refining method is adopted, and the furnace charge is made of secondary or above Composed of steel scrap, return material head, high-quality steelmaking pig iron, sponge iron, etc., tap after EAF oxidation, pre-deoxidize and partially alloy in the ladle, carry out LF / VD argon blowing refining, weakly stir before tapping, and use after tapping and calming Argon protection pouring, hot forging after stripping the steel ingot, controlled chemical composition during the refining process: C = 0.26-0.32%, Si = 0.30-0.50%, Mn = 0.20-0.40%, Ni = 2.30-2.60%, Cr =0.70~0.90%, Mo=0.55~0.70%, V=0.25~0.32%, S≤0.005%, P≤0.013%; then heated in the bottom type gas furnace, the temperature of the heating furnace is 1180℃, and the temperature of the billet is allowed 40°C lower than the furnace temperatur...

Embodiment 3

[0015] Example 3: The mandrel steel type is 28NiCrMoV10, which is formed by material selection-refining-forging-rough machining-heat treatment-finishing. After material selection, the EAF+LF / VD refining method is adopted, and the charge is made of secondary or above Composed of steel scrap, return material head, high-quality steelmaking pig iron, sponge iron, etc., tap after EAF oxidation, pre-deoxidize and partially alloy in the ladle, carry out LF / VD argon blowing refining, weakly stir before tapping, and use after tapping and calming Argon protection pouring, hot forging after stripping the steel ingot, controlled chemical composition during the refining process: C = 0.26-0.32%, Si = 0.30-0.50%, Mn = 0.20-0.40%, Ni = 2.30-2.60%, Cr =0.70~0.90%, Mo=0.55~0.70%, V=0.25~0.32%, S≤0.005%, P≤0.013%; and then heated in a car-bottom gas furnace, the temperature of the heating furnace is 1200°C, and the temperature of the billet is allowed 50°C lower than the furnace temperature to e...

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Abstract

The invention belongs to the technical field of production of mandrels and relates to a method for producing a mandrel by utilizing 28NiCrMoV steel as a raw material. The mandrel is formed by sorting, refining, forging, rough machining, heat treatment and fine machining. The method comprises the following steps of: when refining, pouring into a steel ingot in an EAF and LF / VD way, demoulding the steel ingot and hot conveying to forge; before forging, controlling heating temperature to 1,150-1,200 DEG C and controlling initial forging temperature to 950-1,150 DEG C and final forging temperature to 750 DEG C in the forging process; and carrying out heat treatment in a normalizing and tempering process way. In the forging process, the feeding amount and the rolling reduction of an oil press are strictly controlled during upsetting; the mandrel is forged and moulded by adopting a precise forging machine of 1,400 tons during moulding; pulling and striking speed and deflection can be strictly controlled in a process of forging of the precise forging machine; and a heat treatment process is carried out in the normalizing and tempering way, thereby achieving the effect of improving strength limit and impact toughness.

Description

technical field [0001] The invention belongs to the technical field of mandrel production and relates to a method for producing mandrels using 28NiCrMoV steel as a raw material. Background technique [0002] The mandrel is one of the most important tools necessary for the production of large-diameter seamless steel pipes with modern technology. This product is used in harsh environments during the rolling process of seamless steel pipes. The operating temperature is about 1150°C, and the surface temperature can reach up to About 700°C, and after use, spray water to cool it quickly, and quickly put it on the line again for recycling. During the rolling process, it must bear large and complex tensile and compressive contact stresses and high-speed cycle high-temperature and hot-cold fatigue stresses. The main scrapping defects are surface cracks, ring cracks and cracks caused by scratches on the axis, which are caused by the combined effects of various factors. Domestic mand...

Claims

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Application Information

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IPC IPC(8): B21B25/00C22C38/46C21D8/00
Inventor 赵颖高全德崔晓宁李守杰薛正国徐宁
Owner HENAN ZHONGYUAN SPECIAL STEEL EQUIP MFG CO LTD
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