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Pre-hardening type plastic die steel and preparation method thereof

A plastic mold steel, pre-hardened technology, applied in the field of metallurgical materials, can solve the problems of high pressure and corrosion, low transverse impact toughness, poor wear resistance, etc., achieve uniform and dense structure, improve transverse impact toughness, and improve hardenability Effect

Active Publication Date: 2019-05-03
NORTHEASTERN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0002] Plastic mold is an important process equipment in the plastic molding industry. With the rapid development of the automobile industry and the home appliance industry, the requirements for the performance of plastic mold steel are becoming more and more stringent; mold materials are also changed from low-grade carbon tool steel to alloy tool steel. Development. At present, the largest amount of plastic mold steel used is the P20 series pre-hardened plastic mold steel proposed by the United States; corresponding to my country's national standard is 3Cr2Mo steel, and its working temperature is about 250 ° C. At present, 3Cr2Mo steel has insufficient hardenability, insufficient hardness after quenching and tempering treatment, resulting in poor wear resistance and low transverse impact toughness, which cannot meet the current requirements for high-quality mold steel.

Method used

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  • Pre-hardening type plastic die steel and preparation method thereof
  • Pre-hardening type plastic die steel and preparation method thereof
  • Pre-hardening type plastic die steel and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] The molten steel is smelted by vacuum induction smelting, and then cast into a cylindrical steel ingot with a size of Φ100×200mm. The composition contains C 0.35%, Si 0.34%, Mn 1.30%, Cr 1.96%, Ni 0.91%, P0 .004%, S 0.003%, V 0.10%, the balance is Fe;

[0033] Preheat the steel ingot to 650°C for 3 hours, then heat it to 1250°C at a rate of 80°C / h for a holding time of 5 hours to obtain a heat-treated steel ingot;

[0034] The heat-treated steel ingot is forged, the initial forging temperature is 1200°C, the final forging temperature is 830°C, and then cooled to room temperature with the furnace to obtain the forged steel ingot; when forging, the upsetting ratio is 2.0, the elongation ratio is 2.2, and the total number of forging steps is 5 step;

[0035] Normalize the forged steel ingot first, the normalizing temperature is 880±10°C, and the time is 2h, to obtain the normalized steel ingot;

[0036] The normalized steel ingot is directly subjected to quenching treatm...

Embodiment 2

[0040] Method is with embodiment 1, and difference is:

[0041] (1) The size of the steel ingot is Φ102×195mm, and the composition contains C 0.32%, Si 0.32%, Mn 1.50%, Cr 2.03%, Ni 0.924%, P 0.005%, S 0.003%, V 0.33% by mass percentage;

[0042] (2) The steel ingot is heated to 700°C for 3 hours, then heated to 1200°C at a rate of 70°C / h, and the holding time is 8 hours;

[0043] (3) The initial forging temperature is 1180°C, and the final forging temperature is 810°C; the upsetting ratio during forging is 2.2, the drawing ratio is 4.0, and the total number of forging steps is 8;

[0044] (4) The normalizing temperature is 880±10°C, and the time is 2.5h;

[0045] (5) Heating to 940°C for 2 hours during quenching treatment;

[0046] (6) Tempering treatment at 550°C for 3 hours; the transverse impact energy of the center of the pre-hardened plastic mold steel is 14.0J, the transverse impact energy of the edge is 16.0J, the longitudinal impact energy of the center is 16.6J, an...

Embodiment 3

[0048] Method is with embodiment 1, and difference is:

[0049] (1) The size of the ingot is Φ95×195mm, and the composition contains C 0.36%, Si 0.28%, Mn 1.56%, Cr 2.07%, Ni 0.98%, P 0.004%, S 0.002%, V 0.24% by mass percentage;

[0050] (2) Preheat the steel ingot to 600°C for 4 hours, then heat it to 1230°C at a rate of 90°C / h, and hold for 6 hours;

[0051] (3) The initial forging temperature is 1190°C, and the final forging temperature is 820°C; when forging, the upsetting ratio is 1.8, the drawing ratio is 2.0, and the total number of forging steps is 10;

[0052] (4) The normalizing temperature is 880±10℃, and the time is 3h;

[0053] (5) Heating to 920°C for 2.5 hours during quenching treatment;

[0054] (6) Heat preservation at 510°C for 2 hours during tempering treatment; the transverse impact energy of the center of the pre-hardened plastic mold steel is 16.3J, the transverse impact energy of the edge is 18.1J, the longitudinal impact energy of the center is 19.4J...

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Abstract

The invention discloses pre-hardening type plastic die steel and a preparation method thereof. The pre-hardening type plastic die steel comprises the following components in percentage by mass: 0.32-0.40% of C, 0.20-0.35% of Si, 1.30-1.60% of Mn, 1.80-2.10% of Cr, 0.90-1.15% of Ni, equal to or less than 0.015% of P, equal to or less than 0.005% of S, 0.10-0.35% of V and the balance of Fe; and theisotropic performance is equal to or greater than 0.80. The preparation method comprises the following steps: 1, smelting molten steel to form steel ingot through casting; 2, preheating the steel ingot to 600-700 DEG C, then heating the steel ingot to 1200-1250 DEG C, and carrying out thermal insulation; 3, forging the steel ingot, and cooling the steel ingot along with a furnace; 4, carrying outnormalizing treatment at 880+ / -10 DEG C; 5, carrying out thermal insulation at 900-940 DEG C for 2-3 hours, and then carrying out water cooling; and 6, carrying out tempering at 450-550 DEG C. The pre-hardening type plastic die steel prepared through the preparation method greatly improves the hardenability and the transverse impact toughness.

Description

technical field [0001] The invention belongs to the technical field of metallurgical materials, in particular to a pre-hardened plastic mold steel and a preparation method thereof. Background technique [0002] Plastic mold is an important process equipment in the plastic molding industry. With the rapid development of the automobile industry and the home appliance industry, the requirements for the performance of plastic mold steel are becoming more and more stringent; mold materials are also changed from low-grade carbon tool steel to alloy tool steel. Development. At present, the largest amount of plastic mold steel used is the P20 series pre-hardened plastic mold steel proposed by the United States; corresponding to my country's national standard is 3Cr2Mo steel, and its working temperature is about 250 ° C. At present, 3Cr2Mo steel has insufficient hardenability, insufficient hardness after quenching and tempering treatment, resulting in poor wear resistance and low trans...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C22C38/58C22C38/46C22C33/04C21D8/00
Inventor 李长生任津毅韩亚辉贺帅邱春林高彩茹
Owner NORTHEASTERN UNIV
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