Dynamic isothermal treatment method for high-carbon nano bainite steel structure
A technology of isothermal treatment and bainitic steel, applied in the field of casting, can solve problems such as difficult to accurately calculate the temperature of low-temperature isothermal, reduce the mechanical properties of nano-bainite, and cannot well control the transformation process of nano-bainite
Pending Publication Date: 2021-11-02
DALIAN UNIV OF TECH
View PDF3 Cites 2 Cited by
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Problems solved by technology
However, due to the fact that it is difficult to accurately calculate the temperature of the middle and low temperature isothermal in the second stage, if the isothermal temperature is too high or too low, the effect of the two-stage isothermal treatment will be lost or some high-carbon martensite will be obtained in the final transformation structure, thus Reduce the mechanical properties of nanobainite; at the same time, because the isothermal temperature of different stages in the double-stage isothermal process is fixed, the transformation process of nanobainite cannot be well controlled
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View moreImage
Smart Image Click on the blue labels to locate them in the text.
Smart ImageViewing Examples
Examples
Experimental program
Comparison scheme
Effect test
Embodiment 1
[0026] refer to figure 1 , heating the steel to T 1 =805°C and keep warm for 1h, then quickly put into T 2 =240°C oil bath for dynamic isothermal treatment. Among them, the temperature range of the first stage is 240-216°C (T 3 ), the cooling rate is 0.1°C / min, and the duration is 0-4h; the cooling range of the second stage is 216-120°C (T 4 ), the cooling rate is 0.2°C / min, and the duration is 4-12h; the third stage is low-temperature isothermal treatment, the isothermal temperature is 120°C, and the duration is 12-24h. After the isothermal is over, the sample was air-cooled to room temperature, and finally tempered at 160 °C for 2 h.
[0027] The bainitic ferrite lath in the nano-bainitic steel of Example 1 is observed by a transmission electron microscope as follows image 3 shown. It can be seen that the structure after quenching and tempering is mainly composed of twin martensite. At this time, although the steel has high strength, its toughness is poor, which will...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More PUM
| Property | Measurement | Unit |
|---|---|---|
| size | aaaaa | aaaaa |
Login to View More
Abstract
The invention discloses a dynamic isothermal treatment method for a high-carbon nano bainite steel structure, and belongs to the technical field of casting. The method comprises the steps of complete austenitizing treatment to a high-carbon steel workpiece to be treated; isothermal treatment in an oil bath; setting of the isothermal process to dynamic isothermal treatment of continuous and slow cooling according to the carbon content and Ms point temperature of retained austenite in the structure at different isothermal times; and holding of the isothermal temperature to obtain more nano bainite structures after the isothermal process is cooled such that carbon atoms are difficult to diffuse, finally air cooling to room temperature, and low-temperature tempering. According to the method, the final transformation of nano bainite can be remarkably increased, the thickness of a bainite ferrite lath is refined, and the content of blocky retained austenite is reduced. For the nano bainite steel with different components, a more excellent structure can be obtained through adjustment of the slow cooling rate of the nano bainite steel in different stages, and the comprehensive mechanical property of the nano bainite steel is remarkably improved.
Description
technical field [0001] The invention relates to a preparation method of a steel structure, in particular to a heat treatment method of a nano-bainite steel structure, which belongs to the technical field of casting. Background technique [0002] Due to the nano-scale bainitic ferrite laths and the carbon-rich film-like retained austenite distributed between the laths, the nano-bainite steel has excellent comprehensive mechanical properties and is widely used. It is widely used in the working conditions of large impact load, such as wind power, heavy-duty railway freight car bearings and other parts. The heat treatment of nano-bainitic steel is usually to austenitize the steel and put it in a salt bath condition, and carry out a long-term isothermal treatment at a temperature slightly above the Ms point. However, during the isothermal treatment, there is a process of excess carbon atoms diffusing from the supersaturated bainitic ferrite lath to the surrounding untransformed ...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More Application Information
Patent Timeline
Login to View More Patent Type & AuthorityApplications(China)
IPC IPC(8): C21D1/20
CPCC21D1/20C21D2211/002
Inventor郝海范世超白玉
OwnerDALIAN UNIV OF TECH