Method for obtaining retained austenite in ferrite heat resistant steel T91

A retained austenite, T91 technology, applied in the field of high-chromium ferritic heat-resistant steel production, can solve problems such as applications that cannot be considered and have not been reported

Inactive Publication Date: 2014-06-18
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For steels containing complex carbide-forming elements such as ferritic heat-resistant steels, the application of this process cannot be considered and has not been reported.

Method used

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  • Method for obtaining retained austenite in ferrite heat resistant steel T91
  • Method for obtaining retained austenite in ferrite heat resistant steel T91
  • Method for obtaining retained austenite in ferrite heat resistant steel T91

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Process the T91 steel pipe into a cylindrical sample of Φ5×10mm, and perform the following heat treatment on the DIL805A / D linear dilatometer: heat at 4°C / s to 1100°C, keep it for 10 minutes; then continuously cool to room temperature at 3°C / s . Determine the starting temperature of martensitic transformation (M s ) is 406°C, the martensitic transformation end temperature (M f ) to 210°C.

[0023] Take three new Φ5×10mm cylindrical samples of ferritic heat-resistant steel T91, heat them at 4°C / s to 1100°C, and keep them for 10 minutes; then, cool them at 3°C / s to 380°C (210°C≦380 ℃≦406℃), keep warm for 10min, 25min and 45min respectively, and then continue cooling to room temperature at 3℃ / s.

[0024] figure 1 It is the heat treatment process curve and the curve of linear expansion with time in Example 1. It can be seen from the figure that when the sample is cooled from the austenitizing temperature to 406°C, the martensitic transformation begins to occur; When , ...

Embodiment 2

[0026] Process the T91 steel pipe into a cylindrical sample of Φ5×10mm, and perform the following heat treatment on the DIL805A / D linear dilatometer: heat at 4°C / s to 1100°C, keep it for 10 minutes; then, continuously cool at 3°C / s to room temperature. According to the obtained linear expansion curve with temperature, the starting temperature (Ms) of martensitic transformation in the continuous cooling process of the above heat treatment of T91 steel is determined to be 406°C, and the end temperature (Mf) of martensitic transformation is 210°C.

[0027] Take three new ferritic heat-resistant steel T91 samples and heat them up to 1100°C at 4°C / s and hold for 10 minutes; then cool them to 380°C, 365°C and 350°C at 3°C / s Between 210°C and 406°C), keep it warm for 25 minutes, and then continue to cool to room temperature at 3°C / s.

[0028] Figure 4 It is the XRD pattern of the sample after heat treatment. It can be seen that the presence of retained austenite can be detected in...

Embodiment 3

[0030]Take three Φ5×10mm cylindrical T91 samples and conduct the following heat treatment on an online dilatometer: heat at 4°C / s to 1100°C, hold at 1150°C and 1200°C for 15 minutes each; then continuously cool to room temperature at 3°C / s. According to the obtained curves of linear expansion with temperature, the starting temperature (Ms) and the end temperature (Mf) of martensitic transformation of the three T91 samples during the continuous cooling process of the above heat treatment were respectively determined.

[0031] Take three new ferritic heat-resistant steel T91 samples and heat them at 4°C / s to 1100°C, 1150°C and 1200°C for 15 minutes; then cool at 3°C / s to any one between Ms and Mf. temperature, keep warm for 25min, and then continue to cool down to room temperature at 3°C / s. By detecting the generation of retained austenite during the above heat treatment.

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Abstract

The invention relates to a method for obtaining retained austenite in ferrite heat resistant steel T91. The heat treatment process comprises the following steps: performing heat treatment on a T91 steel pipe subjected to hot rolling, namely heating to the temperature of 1100-1200 DEG C at a speed of 4 DEG C per second, and preserving the temperature for 10-20 minutes; continuously cooling to room temperature at a speed of 3 DEG C per second; determining the initial temperature (Ms) and ending temperature (Mf) of martensite phase transformation of the T91 steel in the heat treatment continuous cooling process according to a changing curve of the obtained linear expansion amount along with temperature; heating another identical T91 steel pipe to the temperature of 1100-1200 DEG C at a speed of 4 DEG C per second, and preserving the temperature for 10-20 minutes; and cooling to an optional temperature between Ms and Mf obtained in the step 1 at a speed of 3 DEG C per second, preserving the temperature for 10-45 minutes, and continuously cooling to room temperature at the speed of 3 DEG C per second. The retained austenite existing in a martensite lath boundary in a film form can be obtained in a sample subjected to heat treatment.

Description

technical field [0001] The invention belongs to the technical field of high-chromium ferritic heat-resistant steel production, and relates to a heat treatment method for obtaining residual austenite in ferritic heat-resistant steel T91. Background technique [0002] The development of heat-resistant steel is closely related to the progress of energy and power machinery. In the fields of new technology development such as thermal power generation, nuclear energy, aerospace, aviation, petroleum and chemical industries, the performance of heat-resistant steel is the key to its success, so the importance of heat-resistant steel is increasing day by day. Especially in recent years, in order to solve the increasingly prominent problems of energy shortage and environmental pollution, high-efficiency super (super) critical pressure power generation has become a hot topic in the world. higher requirement. Due to the long-term service characteristics of heat-resistant steel in high-...

Claims

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Application Information

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IPC IPC(8): C21D6/00C21D11/00
CPCY02P10/20
Inventor 刘永长张程周晓胜高志明余黎明
Owner TIANJIN UNIV
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