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Production method for improving section hardness uniformity of NSM30 plastic mold steel

A technology of plastic mold steel, NSM30, applied in the field of metallurgy, can solve the problems of long production cycle, high price and high use requirements

Active Publication Date: 2019-08-23
NANJING IRON & STEEL CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the high requirements for the use of plastic mold steel, traditional plastic mold steel is produced by electroslag + forging or die casting + forging. Although the internal quality of the product is good and the molding times are high, the production cycle is long and the price is high.

Method used

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  • Production method for improving section hardness uniformity of NSM30 plastic mold steel
  • Production method for improving section hardness uniformity of NSM30 plastic mold steel
  • Production method for improving section hardness uniformity of NSM30 plastic mold steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Select a 320mm thick NSM30 billet, the thickness of the steel plate is 170mm, the compression ratio is 1.88, its chemical composition and mass percentage are: C: 0.35%, Si: 0.42%, Mn: 1.20%, Cr: 1.45%, Mo: 0.18 %, P: 0.016%, S: 0.005%, Al: 0.035%, and the balance is iron.

[0025] The rolling process that present embodiment improves the uniformity of cross-section hardness of NSM30 plastic mold steel comprises the following steps:

[0026] (1) Adopt clean steel smelting method to reduce S and P content in steel, LF refining time is more than 40min, RH vacuum treatment, vacuum degree ≤5mbar and keep for more than 20min, after RH vacuum treatment, H≤1.0ppm. The continuous casting adopts light reduction technology to ensure the internal quality of the 320mm continuous casting slab. The superheating degree of continuous casting molten steel is 5°C to 30°C.

[0027] (2) The temperature of the billet into the furnace is ≥200°C, the preheating section is heated slowly, and t...

Embodiment 2

[0033] Select a 320mm thick NSM30 billet, the steel plate thickness is 140mm, the compression ratio is 2.28, its chemical composition and mass percentage are: C: 0.33%, Si: 0.39%, Mn: 1.26%, Cr: 1.48%, Mo: 0.22 %, P: 0.012%, S: 0.003%, Al: 0.030%, and the balance is iron.

[0034] The rolling process that present embodiment improves the uniformity of cross-section hardness of NSM30 plastic mold steel comprises the following steps:

[0035] (1) Adopt clean steel smelting method to reduce S and P content in steel, LF refining time is more than 40min, RH vacuum treatment, vacuum degree ≤5mbar and keep for more than 20min, after RH vacuum treatment, H≤1.0ppm. The continuous casting adopts light reduction technology to ensure the internal quality of the 320mm continuous casting slab. The superheating degree of continuous casting molten steel is 5°C to 30°C.

[0036] (2) The temperature of the billet into the furnace is ≥200°C, the preheating section is heated slowly, and the temp...

Embodiment 3

[0041] Select a 320mm thick NSM30 billet, the steel plate thickness is 120mm, the compression ratio is 2.67, its chemical composition and mass percentage are: C: 0.35%, Si: 0.42%, Mn: 1.20%, Cr: 1.45%, Mo: 0.18 %, P: 0.016%, S: 0.005%, Al: 0.035%, and the balance is iron.

[0042] The rolling process that present embodiment improves the uniformity of cross-section hardness of NSM30 plastic mold steel comprises the following steps:

[0043] (1) Adopt clean steel smelting method to reduce S and P content in steel, LF refining time is more than 40min, RH vacuum treatment, vacuum degree ≤5mbar and keep for more than 20min, after RH vacuum treatment, H≤1.0ppm. The continuous casting adopts light reduction technology to ensure the internal quality of the 320mm continuous casting slab. The superheating degree of continuous casting molten steel is 5°C to 30°C.

[0044] (2) The temperature of the billet into the furnace is ≥200°C, the preheating section is heated slowly, and the temp...

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Abstract

The invention discloses a production method for improving the section hardness uniformity of NSM30 plastic mold steel. The production method comprises specific processes of converter steel refining-LFrefining-RH vacuum treatment-320 mm continuous cast blank-heating-rolling-tempering; in the heating process of steel blanks, through reduction of the temperature of a soaking section of a heating furnace, the time of the steel blanks in the soaking section is shortened; the steel blanks are cooled on a roller way after discharge from the heating furnace; the surface temperature of the steel blanks is reduced; and the core temperature is higher than the surface temperature, so that the core-surface temperature difference of the steel blanks after heating is increased. The principle of single-pass high pressure is maintained in the steel rolling process to achieve the maximum deformation of core parts of steel plates, so that the thickness direction performance uniformity of steel is improved, and the performances meet requirements after the tempering heat treatment. The section hardness difference of produced NSM30 steel plates is within 25 HBW.

Description

technical field [0001] The invention belongs to the technical field of metallurgy and relates to a production process for improving the hardness uniformity of the section of NSM30 plastic mold steel. Background technique [0002] NSM30 is a pre-hardened alloy plastic mold steel, which is suitable for the processing and manufacturing of large and medium-sized plastic molds with high requirements for plastic mold cavity roughness, and is used to make large-sized, long-life, and high-grade plastic molds. Due to the high requirements for the use of plastic mold steel, traditional plastic mold steel is produced by electroslag + forging or die casting + forging. Although the internal quality of the product is good and the molding times are high, the production cycle is long and the price is high. In recent years, with the improvement of the control ability and precision of continuous casting equipment, high-quality casting slabs can be produced. The rolling force of the rolling mi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/22C21D8/02C21D11/00C22C33/04
CPCC21D8/0205C21D8/0226C21D8/0247C21D11/00C22C33/04C22C38/02C22C38/04C22C38/06C22C38/22
Inventor 姜在伟温永红闫强军刘通王新
Owner NANJING IRON & STEEL CO LTD
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