A method to determine the tempering temperature of 718h pre-hardened plastic mold steel
A technology of plastic mold steel and tempering temperature, applied in the field of heat treatment of metal materials, can solve the problem that the relationship between tempering temperature and hardness value is not clearly corresponding, and achieve the effect of small mechanical properties and good isotropy
Active Publication Date: 2019-06-07
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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Problems solved by technology
However, according to the existing heat treatment process, there is no clear correspondence between tempering temperature and hardness value.
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[0028] see figure 1 , figure 2 , image 3 with Figure 4 , the present embodiment determines the method for the tempering temperature of 718H pre-hardened plastic mold steel, comprising the following steps:
[0029] (1) Use the thermal expansion method to measure the Ac1 and Ac3 point temperatures of 718H pre-hardened plastic mold steel to formulate the subsequent heat treatment temperature range. In order to prepare the experimental results, 10 different cooling rates were selected to obtain 10 groups of Ac1 and Ac3 points , taking the mean value, as shown in Table 1;
[0030] Table 1 shows Ac1 and Ac3 points measured at different austenite cooling rates:
[0031]
[0032] (2) Roughly process the on-demand heat-treated steel into 3 standard U-shaped impact specimens and 3 standard tensile specimens;
[0033] (3) The processed samples were heated up to 870°C at a heating rate of 100°C / h, kept for 2 hours and air-cooled to room temperature for ultra-fine tissue treatme...
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The invention relates to the field of heat treatment of metallic materials, in particular to a method for determining the tempering temperature of 718H pre-rigid plastic die steel. Steel materials needing heat treatment are subjected to rough machining into standard U-shaped impact specimens and standard tensile specimens; the divided steel materials are heated to 870 DEG C with the temperature increasing rate being 100 DEG C / h, heat preservation is conducted for 2 h, the steel materials are air-cooled to the room temperature, and structure super-refining treatment is conducted; then the steel materials are heated to 860 DEG C with the same heating rate and cooled to the room temperature in a water-air alternate mode after heat preservation is conducted for 1 h, and the water temperature is 25 DEG C; after treatment, seven tempering temperature points are selected in the determined tempering temperature range, then the specimens are tempered, subjected to heat preservation for 2 h and then oil-cooled to the room temperature; the tempered specimens are subjected to finish machining into standard U-shaped impact specimens and standard tensile specimens, and the impact value, the tensile value and the hardness value are detected at the room temperature; and the relation between the tempering temperature and the impact value, the tempering temperature and the tensile value as well as the tempering temperature and the hardness value are drawn, and the most suitable tempering temperature is selected through the mechanical property of the composite demand.
Description
technical field [0001] The invention relates to the field of heat treatment of metal materials, in particular to a method for determining the tempering temperature of 718H pre-hardened plastic mold steel. Background technique [0002] Pre-hardened plastic mold steel is widely used because it does not require subsequent heat treatment after processing, which can avoid quality problems such as decarburization, cracking, and deformation of the mold, and occupies a relatively large share in the mold steel market. 718H pre-hardened plastic mold steel has good hardenability and excellent performance, and is mainly used to manufacture large-size, long-life, high-grade plastic molds. Due to the high service performance requirements of the steel, in addition to ensuring extremely high metallurgical quality, its hot rolling and heat treatment production processes must also be strictly controlled to obtain a uniform and stable microstructure and hardness. The technical requirements fo...
Claims
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IPC IPC(8): C21D6/00C21D1/18
CPCC21D1/18C21D6/00
Inventor 傅排先刘航航刘宏伟李殿中
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI