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Precise heat treatment quenching technology for cold working tool steel precision part

A technology for cold work tool steel and precision parts, which is applied in the field of precise heat treatment and quenching process, and can solve problems such as difficulty in accurately and reliably controlling the change of crystal phase structure, large influence of heat treatment process of alloy composition, thermal instability of retained austenite, etc. , to achieve high engineering application value, significant social and economic benefits, and the effect of grain refinement

Inactive Publication Date: 2018-09-04
黄石高校智源技术咨询服务有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The thermal conductivity of cold work tool steel is poor, and the thickness of the workpiece and the composition of the alloy also have a great influence on the heat treatment process, resulting in a complicated heat treatment process. If the heat treatment is improper, it is not only difficult to exert its excellent performance, but also difficult to control the quality. Therefore, the inventor has declared A heat treatment and quenching process patent for cold-work tool steel precision parts (application number 2017112175231), which has achieved good results;
[0004] The mold upper spacer and garbage nail in the semiconductor chip precision plastic sealing mold are made of ASSAB DF-2 material. Due to the complicated force of the mold during use, some working parts of the mold need to have some special mechanical properties, which are harmful to the parts. Accurate hardness requirements and high working dimensional stability, if the standard heat treatment process is often unable to meet the ideal work performance requirements, it is necessary to properly adjust the basic characteristics such as hardness, toughness and wear resistance through heat treatment to achieve the best mold Working state, quenching temperature and tempering temperature are the main process parameters of heat treatment, and the thickness of the parts is different. According to the thickness of the workpiece, use the empirical formula t=αКН to estimate the holding time in the heat treatment process. Not only is it difficult to accurately and reliably control its quenching hardness , it is also difficult to accurately and reliably control the change of the crystal phase structure inside the material, and a small amount of residual austenite is unstable when heated, causing the parts to creep during the working process, and it is difficult to meet the requirements of use; this requires different workpiece thicknesses, different Hardness requirements, adopt precise heat treatment temperature and time process parameters to precisely control the internal structure changes, carbide precipitation, grain growth, to ensure very little retained austenite and residual stress

Method used

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  • Precise heat treatment quenching technology for cold working tool steel precision part

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Example 1 A cold work tool steel workpiece with a thickness of less than 5mm, the hardness requirement is HRC53

[0020] (1) Put a batch of workpieces with a thickness of less than 5mm into the quenching furnace and preheat them twice. The first time the heating rate is less than 75°C / hour to 100°C, and the second time is less than 115°C / hour. to 150°C;

[0021] (2) The workpiece is heated to 550°C in the quenching furnace and held for 15 minutes, and then heated to the quenching temperature of 830°C and held for 10 minutes;

[0022] (3) Put the workpiece out of the furnace into the oil tank, keep the oil temperature at 50-80°C, start the mixer, and when the workpiece cools to 140°C, take it out of the tank and air cool it to 50-70°C;

[0023] (4) When the workpiece is air-cooled to 50°C-70°C, immediately put it into the tempering furnace and heat it to 400°C for tempering and keep it for 90 minutes, and then it is naturally air-cooled when it comes out of the furnace;...

Embodiment 2

[0026] Example 2 A cold work tool steel workpiece with a thickness of 6-10mm, the hardness requirement is HRC55

[0027] (1) Put a batch of workpieces with a thickness of 6-10mm into the quenching furnace to preheat twice, the first heating rate is less than 75 ° C / hour to 100 ° C, the second heating rate is less than 115 ° C / hour Speed ​​up to 150°C;

[0028] (2) The workpiece is heated to 550 in the quenching furnace 0 C and keep it warm for 20min, then continue heating to the quenching temperature of 830 0 C and keep warm for 15min;

[0029] (3) Put the workpiece out of the furnace into the oil tank, keep the oil temperature at 50-80°C, start the mixer, and when the workpiece cools to 140°C, take it out of the tank and air cool it to 50-70°C;

[0030] (4) When the workpiece is air-cooled to 50 0 C-70 0 C immediately into the tempering furnace to heat to 350 0 C Temper and keep warm for 90 minutes, then take out of the oven and cool in air naturally;

[0031] (5) ...

Embodiment 3

[0033] Example 3 A cold work tool steel workpiece with a thickness of 11-15mm, the hardness requirement is HRC57

[0034] 1. Put a batch of workpieces with a thickness of 11-15mm into the quenching furnace and preheat them twice. The first time the heating rate is less than 75°C / hour to 100°C, and the second time is less than 115°C / hour. to 150°C;

[0035] 2. The workpiece is heated to 550 in the quenching furnace 0 C and keep it warm for 30min, then continue heating to the quenching temperature of 830 0 C and keep warm for 22min;

[0036] 3. Put the workpiece out of the furnace into the oil tank, keep the oil temperature at 50-80°C, start the mixer, when the workpiece cools to 140°C, take it out of the tank and air cool it to 50-70°C;

[0037] 4. When the workpiece is air-cooled to 50 0 C-70 0 C immediately into the tempering furnace to heat to 300 0 C Temper and keep warm for 120min, take out of the oven and cool in air naturally;

[0038] 5. When the workpiece is air...

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Abstract

The invention mainly relates to a precise heat treatment quenching technology for a cold working tool steel precision part. The material of the cold working tool steel precision part is highly-pure cold working tool steel ASSAB DF-2 imported from Sweden, and the main alloy component of the highly-pure cold working tool steel ASSAB DF-2 comprises 0.9% of C, 0.5% of Cr, 0.5% of W and 0.1% of V. Thetechnology mainly comprises the following steps: (1) placing workpieces having a thickness difference of below 5 mm in a quenching furnace, preheating the workpieces to 100 DEG C at a heating rate ofbelow 75 DEG C / h, and then heating the workpieces to 150 DEG C at a heating rate of below 115 DEG / h; (2) performing two-stage heating in the quenching furnace to a quenching temperature of 830 DEG C,and keeping the temperature; (3) discharging the workpieces from the furnaces, and performing oil quenching on the workpieces in an oil tank; and (4) adding the workpieces into a tempering furnace intwo times, performing T DEG C heat insulation tempering, discharging the workpieces, and performing air cooling to room temperature (as shown in Fig 1). Accurate heat treatment temperature and time process parameters are adopted according to different workpiece thicknesses and different hardness requirements in order to accurately control the internal microstructure change of a material and the precipitation form and crystal grain growth of carbide in order to eliminate residual austenite, precipitate ultrafine carbides and keep the crystal grains fine and the microstructure uniform, so a precise part hardness is achieved, and the parts do not creep and keep a stable size in the use process.

Description

technical field [0001] The invention belongs to the field of heat treatment of cold work tool steel materials, and in particular relates to a precision heat treatment quenching process for precision parts of cold work tool steel. Background technique [0002] With the upgrading of my country's manufacturing industry, some precision equipment has more and more stringent requirements for parts and components. Domestic materials cannot meet their requirements in some aspects of performance, so relevant advanced imported materials have to be used; ASSAB DF-2 is a Swedish brand, and its The main alloy composition is 0.9%C 0.5%Cr 0.5%W 0.1%V. It has high purity and uniform grain refinement. It is similar to American AISIO1. It is often called non-deformable oil steel. The commonly used quenching hardness is HRC56-HRC62; this steel After heat treatment, it has the characteristics of not easy to deform, suitable for manufacturing precision tools, precision instruments, precision measu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/18C22C38/22C22C38/24
CPCC21D1/18C22C38/22C22C38/24
Inventor 不公告发明人
Owner 黄石高校智源技术咨询服务有限公司