Experimental and theoretical studies of bainitic creep-resisting T23 steel

SVOBODOVÁ, Marie and Jiří SOPOUŠEK. Experimental and theoretical studies of bainitic creep-resisting T23 steel. In CALPHAD XXXVIII (May 17-22, 2009). 2009.

Basic information

Original name

Experimental and theoretical studies of bainitic creep-resisting T23 steel

Name in Czech

Experimentální a teoretická studie bainitických creepově odolných T23 ocelí

Name (in English)

Experimental and theoretical studies of bainitic creep-resisting T23 steel

Authors

SVOBODOVÁ, Marie (203 Czech Republic, guarantor) and Jiří SOPOUŠEK (203 Czech Republic, belonging to the institution)

Edition

CALPHAD XXXVIII (May 17-22, 2009), 2009

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Other information

Language

Czech

Type of outcome

Konferenční abstrakt

Field of Study

10403 Physical chemistry

Country of publisher

Slovakia

Confidentiality degree

není předmětem státního či obchodního tajemství

RIV identification code

RIV/00216224:14310/09:00051151

Organization unit

Faculty of Science

Keywords (in Czech)

CALPHAD; svar; fázové diagramy; ocel

Keywords in English

CALPHAD; weld; phase diagram; steel

Tags

CALPHAD, IK, Phase diagram, rivok, steel, weld

Tags

International impact

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Abstract

V originále

CALPHAD approach is a progressive tool of material engineering helping in a development of new advanced materials. Based on this approach, we can make phase diagram calculations and predictions, and simulate diffusion-controlled phase transformation, too. In a view of the application, these phase diagrams calculations play a significant role in a, i.e., prediction of thermal-induced structure changes in new materials supposed to be used for power industry. Furthermore, perhaps all structural parts of power plants are welded, so, if the operation temperature is achieving values above 500stC, the simulations of diffusion-controlled phase transformations occurring in so thermal loaded weld joints enable to predict their structure stability and then a service lifetime of all the structural part. One of those new materials supposed to be used for power industry is bainitic creep-resisting T23 steel, a modification of low-alloyed 2.25Cr-1Mo steel, containing Cr (2.25 wt.%), Mo (0.1 wt.%), C, V, Mn (each 0.2 wt.%), and B, N (each 0.006 wt.%). Moreover, T23 steel is alloyed with 1.6 wt.% of W and 0.04 wt.% of Nb. Due to addings, as-treated steel has an improved creep resistance, high elastic-plastic properties, and a good weldability. Therefore, T23 steel is said to be use for power components at operating conditions up to 600degC. Because of, considering a service lifetime of components, a necessary prediction of long-term structure, corrosion, and strength behaviour of the material, our research was focused on study of structure behaviour of T23 steel at long-term isothermal exposure at 650degC. In opposite to 100 000 hrs exposure at 600stC (maximum service temperature), the increased temperature allows to get same degraded structure of steel after already 10 000 hrs. The thermal-induced phase transformations of as-received, as-welded, and as-exposed T23 steel were predicted by using Thermo-Calc and DICTRA. At the same time, XRD analysis, light and electron microscopy, and Vickers hardness measurement were used.

In English

CALPHAD approach is a progressive tool of material engineering helping in a development of new advanced materials. Based on this approach, we can make phase diagram calculations and predictions, and simulate diffusion-controlled phase transformation, too. In a view of the application, these phase diagrams calculations play a significant role in a, i.e., prediction of thermal-induced structure changes in new materials supposed to be used for power industry. Furthermore, perhaps all structural parts of power plants are welded, so, if the operation temperature is achieving values above 500stC, the simulations of diffusion-controlled phase transformations occurring in so thermal loaded weld joints enable to predict their structure stability and then a service lifetime of all the structural part. One of those new materials supposed to be used for power industry is bainitic creep-resisting T23 steel, a modification of low-alloyed 2.25Cr-1Mo steel, containing Cr (2.25 wt.%), Mo (0.1 wt.%), C, V, Mn (each 0.2 wt.%), and B, N (each 0.006 wt.%). Moreover, T23 steel is alloyed with 1.6 wt.% of W and 0.04 wt.% of Nb. Due to addings, as-treated steel has an improved creep resistance, high elastic-plastic properties, and a good weldability. Therefore, T23 steel is said to be use for power components at operating conditions up to 600degC. Because of, considering a service lifetime of components, a necessary prediction of long-term structure, corrosion, and strength behaviour of the material, our research was focused on study of structure behaviour of T23 steel at long-term isothermal exposure at 650degC. In opposite to 100 000 hrs exposure at 600stC (maximum service temperature), the increased temperature allows to get same degraded structure of steel after already 10 000 hrs. The thermal-induced phase transformations of as-received, as-welded, and as-exposed T23 steel were predicted by using Thermo-Calc and DICTRA. At the same time, XRD analysis, light and electron microscopy, and Vickers hardness measurement were used.