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Method for preparing 24CrNiMo bainite alloy steel by using selective laser melting technology

A laser selective melting and alloy steel technology, applied in the field of materials, can solve the problems of complex phase and phase transformation, complex heat treatment process, high manufacturing cost, and achieve excellent mechanical properties, good strength-toughness matching relationship, and excellent strength-toughness matching. Effect

Active Publication Date: 2017-09-29
NORTHEASTERN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

24CrNiMo alloy steel is used to manufacture high-speed rail brake discs. Traditional manufacturing methods mainly use casting, forging, subsequent heat treatment, and finishing. There are problems such as long production cycle, high manufacturing cost, and complicated heat treatment process. At the same time, the core technology is monopolized by foreign countries. Formed related technology protection
[0004] In recent years, the research and application of laser selective melting technology on iron-based alloys include 316L and 304 stainless steel. After rapid forming, all or most of the structure is austenite, the tensile strength at room temperature is 500Mpa, and the elongation reaches 30%. , with a strong plasticity of 15GPa·%; and applied to 18Ni-300 martensitic precipitation hardening steel and H13 high-speed steel, most of the structure after rapid forming is composed of martensite. Although the tensile strength can reach 1200Mpa, the elongation is only About 6%, the strong plastic product is only 7.2Gpa·%. In addition, due to the large structural stress brought by the martensitic transformation, cracks and other defects are easy to occur during the selective laser melting process.
At the same time, there are few researches and applications on laser additive manufacturing of low-alloy high-strength structural steel, which is the most used in national economic construction. Complicated
In particular, there is no report on the laser selective melting process, microstructure and properties of 24CrNiMo alloy steel.

Method used

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  • Method for preparing 24CrNiMo bainite alloy steel by using selective laser melting technology
  • Method for preparing 24CrNiMo bainite alloy steel by using selective laser melting technology
  • Method for preparing 24CrNiMo bainite alloy steel by using selective laser melting technology

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Effect test

Embodiment 1

[0052] The 24CrNiMo bainite alloy steel high-speed iron brake disc is prepared by laser selective melting technology. The laser selective melting equipment used in it includes semiconductor lasers, computer systems for forming control, powder spreading device forming cylinders and atmosphere protection devices. The details are as follows Steps to implement:

[0053] Step 1: Raw material powder preparation:

[0054] (1) 24CrNiMo alloy steel powder material, the powder contains the following elements in mass percent (Wt%) content: C: 0.27%, Cr: 0.97%, Ni: 0.98%, Mo: 0.50, Mn: 0.91%, Si: 0.52 %, O: 0.02%, the balance is Fe; the sum of the mass percentages of the above elements is 100%;

[0055] (2) Sieve the above-mentioned alloy steel powder, and the particle size distribution range is preferably 15-53 μm; before use, heat it at 80° C. for 5 hours in a vacuum drying oven, and perform drying treatment;

[0056] Step 2: Formulation of scanning path and laser process parameters ...

Embodiment 2

[0079] Utilize laser selective melting technique to prepare 24CrNiMo bainite alloy steel metal sample, preparation method is the same as embodiment 1, wherein difference is to change the powder pretreatment drying temperature and time in (2) of step 1, step 2 (1) The layer thickness of the three-dimensional model in layered discrete processing, the laser selective melting process parameters in (2), the thickness of the 24CrNiMo powder layer in step 3 (2) and the volume energy density in step 3 (3), specifically:

[0080] Drying temperature and time of powder pretreatment: before use, heat it in a vacuum drying oven at 100°C for 8 hours for drying treatment;

[0081] Layer thickness during layered discrete processing of the 3D model: construct a 3D model of the part to be formed, and use the programming software that comes with the laser to perform layered discrete processing of the 3D data of the part to be formed. The thickness of each layer is uniform, and the thickness is se...

Embodiment 3

[0099] Utilize laser selective melting technique to prepare 24CrNiMo bainite alloy steel metal sample, preparation method is the same as embodiment 1, wherein difference is to change the powder pretreatment drying temperature and time in (2) of step 1, step 2 (1) The layer thickness of the three-dimensional model in layered discrete processing, the laser selective melting process parameters in (2), the thickness of the 24CrNiMo powder layer in step 3 (2) and the volume energy density in step 3 (3), specifically:

[0100] Drying temperature and time of powder pretreatment: before use, heat it in a vacuum drying oven at 90°C for 7 hours for drying treatment;

[0101] Layer thickness during layered discrete processing of the 3D model: construct a 3D model of the part to be formed, use the programming software that comes with the laser to perform layered discrete processing of the 3D data of the part to be formed, the thickness of each layer is uniform, and the thickness is set to ...

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Abstract

The invention provides a method for preparing 24CrNiMo bainite alloy steel by using a selective laser melting technology. The method includes the steps that a laser device is used for conducting scanning on 24CrNiMo alloy steel power which is spread out on a base plate according to a preset selective laser melt scanning route till the power melts. According to the method, by optimizing technology parameters, taking use of the effects of alloy elements such as C, Cr, Ni, Mo, the bainite alloy steel which is uniform in microstructure is obtained at a high selective laser melting cooling speed, the average micro-hardness of the obtained bainite microstructure reaches 330-346 HV, the tensile strength is 962-978 Mpa, the elongation ratio is 16.4-17.6%, the product of tensile strength and elongation reaches 16.1-16.9 Gpa%, and the microstructure has excellent matched strength and toughness. The method and the technology are mainly applied to selective laser melting manufacture of 24CrNiMo alloy steel high speed rail brake discs.

Description

technical field [0001] The invention belongs to the technical field of materials, and in particular relates to a method for preparing high-strength and toughness 24CrNiMo bainite alloy steel by using laser selective melting technology. Background technique [0002] Cr-Ni-Mo series low-alloy high-strength steel has good strength, toughness and high heat resistance, and is currently commonly used steel for high-speed train brake discs. 24CrNiMo alloy steel is used to manufacture high-speed rail brake discs. The traditional manufacturing methods mainly use casting, forging and subsequent heat treatment, finishing and other manufacturing methods. There are problems such as long production cycle, high manufacturing cost, and complicated heat treatment process. At the same time, the core technology is monopolized by foreign countries. Related technology protection has been formed. [0003] Laser selective melting technology is a brand-new manufacturing technology integrating comp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F3/105B33Y10/00C22C38/44C22C38/02C22C38/04
CPCC22C38/02C22C38/04C22C38/44B33Y10/00C21D2211/002B22F10/00B22F12/30B22F10/34B22F10/28B22F10/36B22F10/366B22F10/32Y02P10/25
Inventor 陈岁元魏明炜刘常升郭快快梁京崔彤
Owner NORTHEASTERN UNIV
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