Properties, structure and creep resistance of austenitic steel Super 304H

This article presents the results of investigations on HR6W alloy and Sanicro 25 steel and the dissimilar welded joint made of them. The characteristic images of microstructure of the investigated materials in the as-received condition and following the creep test, observed with a scanning electron microscope (SEM), are shown. The X-ray analysis of phase composition of the existing precipitates was carried out. The method for evaluation of creep strength based on abridged creep tests carried out at a temperature higher than the design one is presented. The obtained results do not deviate from the values of creep strength determined in longterm creep tests. The maximum difference in creep strength of the investigated materials is ±20%, which is in compliance with the acceptable scatter band. The methodology presented can be used for verification of creep strength (life time) of the material of finished components to be operated under creep conditions.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of Creep Strength of Heterogeneous Welded Joint in HR6W Alloy and Sanicro 25 Steel

Zieliński¹,

Dobrzański²,

Purzyńska³

et al. 2017

“…To reduce the CO 2 level in the atmosphere and save fossil fuels, it is necessary to improve the efficiency in the electric energy production. It allows the development of new steels and alloys for service at elevated and high temperatures [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Long-Term Impact of Elevated Temperature on Changes in Microstructure and Mechanical Properties of HR3C Steel

Zieliński

Sroka

Hernas

et al. 2016

The HR3C is a new steel for pressure components used in the construction of boilers with supercritical working parameters. In the HR3C steel, due to adding Nb and N, the compounds such as MX, CrNbN and M23C6 precipitate during service at elevated temperature, resulting in changes in mechanical properties. This paper presents the results of microstructure investigations after ageing at 650, 700 and 750 °C for 5,000 h. The microstructure investigations were carried out using scanning and transmission electron microscopy. The qualitative and quantitative identification of the existing precipitates was carried out using X-ray analysis of phase composition. The effect elevated temperature on microstructure and mechanical properties of the examined steel was described.

“…The obtained test results allow the residual life and disposable residual life to be determined and are the basic source of information for evaluation of forecasting the time of safe operation of materials. Such a method for conducting creep tests was verified based on long-term creep tests, and the results of examinations were the subject of numerous publications [14][15][16]20,21]. The obtained results of abridged creep tests for HCM12 steel after service are presented graphically in Fig.…”

Section: Creep Tests -Determination Of Residual Life For Hcm12 Steelmentioning

confidence: 98%

Assessment of Service Life of HCM12 Steel After 100 000 Hrs of Service

Zieliński¹,

Paszkowska²,

Skupień³

et al. 2016

The subject of the research was a material in the form of a ϕ38×4 pipe from HCM12 steel used for steam superheater coils in power boilers with supercritical and ultra-supercritical steam parameters. This article presents results of investigations of mechanical properties and microstructure of material of the examined tube in the as-received condition and after 100,000 h service at 585°C under creep conditions. Creep tests were carried out for the material after 100,000 h service to determine the disposable residual life. The impact of changes in mechanical properties and degradation of the microstructure on the loss of creep resistance compared to the as-received condition was assessed. The investigations have revealed that the examined steel after 100,000 h service meets the requirements for this steel in the as-received condition with regard to strength properties at room and elevated temperature. The creep tests have revealed a significant loss of creep resistance, which was estimated at around 60-70% compared to the as-received condition.