Experimental estimation of the deformation criterion of long-term (creep) strength

1972 ◽  
Vol 4 (1) ◽  
pp. 20-24
Author(s):  
N. A. Borodin ◽  
N. I. Borshchev
Keyword(s):  
Creep Strength ◽  
Deformation Criterion ◽  
Experimental Estimation ◽  
Term Creep

scholarly journals Effects of Full Annealing Heat Treatment on Long-term Creep Strength of 2.25Cr-1Mo Steel Welded Joint

2003 ◽  
Vol 21 (2) ◽  
pp. 195-203 ◽  
Author(s):  
Kazuhiro KIMURA ◽  
Takashi WATANABE ◽  
Hiromichi HONGO ◽  
Masayoshi YAMAZAKI ◽  
Jun-ichi KINUGAWA ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Creep Strength ◽  
Welded Joint ◽  
Annealing Heat Treatment ◽  
Full Annealing ◽  
Term Creep ◽  
Annealing Heat

Inherent creep strength and long term creep strength properties of ferritic steels

1997 ◽  
Vol 234-236 ◽  
pp. 1079-1082 ◽  
Author(s):  
K. Kimura ◽  
H. Kushima ◽  
F. Abe ◽  
K. Yagi
Keyword(s):  
Creep Strength ◽  
Strength Properties ◽  
Ferritic Steels ◽  
Term Creep

scholarly journals Effect of Initial Microstructure on Long-term Creep Strength Properties of 2.25Cr-1Mo Steel

1999 ◽  
Vol 85 (11) ◽  
pp. 848-855 ◽  
Author(s):  
Hideaki KUSHIMA ◽  
Kazuhiro KIMURA ◽  
Fujio ABE ◽  
Koichi YAGI ◽  
Hirosada IRIE ◽  
...  
Keyword(s):  
Creep Strength ◽  
Strength Properties ◽  
Initial Microstructure ◽  
Term Creep

scholarly journals Long-term Creep Strength Property and Microstructural Stability of 12Cr Steel

1995 ◽  
Vol 81 (3) ◽  
pp. 214-219 ◽  
Author(s):  
Hideaki KUSHIMA ◽  
Kazuhiro KIMURA ◽  
Koichi YAGI ◽  
Kouichi MARUYAMA
Keyword(s):  
Strength Property ◽  
Creep Strength ◽  
Microstructural Stability ◽  
Term Creep

Regulatory Review Results on Allowable Tensile Stress Values of Creep Strength Enhanced Ferritic Steels

2007 ◽  
Author(s):  
Kazuo Yoshida ◽  
Hirotake Nakai ◽  
Minami Fukuda
Keyword(s):  
Creep Strength ◽  
Rupture Life ◽  
Ferritic Steels ◽  
Regulatory Review ◽  
Tensile Stresses ◽  
Life Evaluation ◽  
Term Creep ◽  
Region Splitting ◽  
Review Current

In order to evaluate long-term creep strength and to review current allowable tensile stresses of creep strength enhanced ferritic steels, a committee was organized in Japan Power Engineering and Inspection Corporation. In 2004FY and 2005FY, creep test data of Gr. 122, Gr. 91, Gr. 92, Gr. 23 and KA-SUS410J2TB steels were collected and analyzed by means of region splitting procedure in the committee. Based on the analysis, the allowable tensile stresses were reviewed in accordance with METI regulatory base. And the master curves for creep rupture life evaluation of welds were set forth furthermore based on the data analysis.

Creep Strength Evaluation of Welded Joint Made of Modified 9Cr-1Mo Steel for Japanese Sodium Cooled Fast Reactor (JSFR)

2010 ◽  
Author(s):  
Takashi Wakai ◽  
Yuji Nagae ◽  
Takashi Onizawa ◽  
Satoshi Obara ◽  
Yang Xu ◽  
...  
Keyword(s):  
Creep Strength ◽  
Welded Joints ◽  
Welded Joint ◽  
Strength Degradation ◽  
Creep Rupture ◽  
Primary Circuit ◽  
Allowable Stress ◽  
Type Iv ◽  
Term Creep

This paper describes a proposal of provisional allowable stress for the welded joints made of modified 9Cr-1Mo steel (ASME Gr.91) applicable to the structural design of Japanese Sodium cooled Fast Reactor (JSFR). For the early commercialization of the SFRs, economic competitiveness is one of the most essential requirements. One of the most practical means to reduce the construction costs is to diminish the total amount of structural materials. To meet the requirements, modified 9Cr-1Mo steel has attractive characteristics as a main structural material of SFRs, because the steel has both excellent thermal properties and high temperature strength. Employing the steel to the main pipe material, remarkable compact plant design can be achieved. There is only one elbow in the hot leg pipe of the primary circuit. However, in such a compact piping, it is difficult to keep enough distance between welded joint and high stress portion. In the welded joints of creep strength enhanced ferritic steels including ASME Gr.91 (modified 9Cr-1Mo) steel, creep strength may obviously degrade especially in long-term region. This phenomenon is known as “Type-IV” damage. Though obvious strength degradation has not observed at 550°C yet for the welded joint made of modified 9Cr-1Mo steel, it is proper to suppose strength degradation must take place in very long-term creep. Therefore, taking strength degradation due to “Type-IV” damage into account, the allowable stress applicable to JSFR pipe design was proposed based on creep rupture test data acquired in temperature accelerated conditions. Available creep rupture test data of welded joints made of modified 9Cr-1Mo steel provided by Japanese steel vender were collected. The database was analyzed by region partition method. The creep rupture data were divided into two regions of short-term and long-term and those were individually evaluated by regression analyses with Larson Miller Parameter (LMP). Boundary condition between short-term and long-term was half of 0.2% proof stress of base metal at corresponding temperature. First order equation of logarithm stress was applied. For conservativeness, allowable stress was proposed provisionally considering design factor for each region. Present design of JSFR hot leg pipe of primary circuit was evaluated using the proposed allowable stress. As a result, it was successfully demonstrated that the compact pipe design was assured. For validation of the provisional allowable stress, a series of long-term creep tests were started. In future, the provisional allowable stress will be properly reexamined when longer creep rupture data are obtained. In addition, some techniques to improve the performance of welded joints were surveyed and introduced.

Grades 92 and 23: Weldability Assessment and Long-Term Performances for Power Generation Applications

2008 ◽  
Vol 580-582 ◽  
pp. 383-388
Author(s):  
Emmanuel Bauné ◽  
E. Galand ◽  
B. Leduey ◽  
G. Liberati ◽  
G. Cumino ◽  
...  
Keyword(s):  
Creep Strength ◽  
Welded Joints ◽  
Power Plants ◽  
Product Family ◽  
Base Material ◽  
Advanced Materials ◽  
Creep Properties ◽  
Steam Parameters ◽  
Term Creep

Increased efficiency and emission reduction in modern power plants lead to the use of new advanced materials with enhanced creep strength, with the objective to increase the steam parameters of power plants. With over ten years on market and wide experience related to its use, ASTM Grade 92 is becoming one of the most required materials when high service temperatures are reached (max. 610°C). Its composition, with 9%Cr and 1.5%W, gives rise to martensitic microstructures which offer very high creep strength and long term stability. The improved weldability and creep-strength between 500 and 580°C of the low alloy ASTM Grade 23, as well as a cost advantage over higher Cr materials in this temperature range, make it one of the possible candidates to meet the stringent requirements of modern power plants. Air Liquide Welding (ALW) has optimized and distributes a complete product family for the welding of Grades 23 and 92. TenarisDalmine (TD) focused on the development of Grade 23 tubes and pipes and is working on the development of Grade 92. A deep characterization work of the microstructural evolution and long term creep performances of these high temperature resistant materials was thus undertaken by ALW and TD, in collaboration with the Centro Sviluppo Materiali (CSM). The joint characterization program consisted in the assessment of welded joints creep properties. Welded joints were produced using the gas tungsten (GTAW), shielded metal (SMAW) and submerged arc welding (SAW) processes. Mechanical and creep properties of weldments were measured both in the as welded and post weld heat treated conditions and proper WPS’s were designed in a manner such that industrial production needs were satisfied. Short term creep resistance of cross weld specimens was measured to be within the base material acceptance criteria. Long term base material and cross weld creep performance evaluation are now in progress.

Quantitative Evaluation of Secondary Phases in a Weld Joint Made of COST F and FB2 Creep Resistant Steels

2017 ◽  
Vol 270 ◽  
pp. 183-188
Author(s):  
Dagmar Jandová
Keyword(s):  
Quantitative Evaluation ◽  
Creep Strength ◽  
Weld Joint ◽  
Precipitate Size ◽  
Secondary Phases ◽  
Creep Tests ◽  
Transmission Electron ◽  
Creep Resistant Steels ◽  
Term Creep

Conventional (CCT) and accelerated (ACT) creep tests of a weld joint made of COST F and COST FB2 steels were carried out over a temperature range from 550 °C to 650 °C. Fracturing of the crept specimens was located in the heat affected zone (HAZ) of the F steel. Two specimens were selected after CCT and ACT for quantitative evaluation of the precipitates and compared to the weld joint in as-received conditions. Scanning and transmission electron micrographs were used to measure the precipitate size. Both methods were compared and the accuracy of the results was discussed. It was concluded that ACT can simulate the precipitation of chromium carbides and structure recovery during long term creep exposures. However, precipitation of Laves phase during CCT was not recorded after ACT. Therefore, it is difficult to use ACT in this experiment for estimating the long term creep strength.

Long-term creep strength and fracture of Gr.91 steel welds

2017 ◽  
Vol 34 (5-6) ◽  
pp. 466-472 ◽  
Author(s):  
Masaaki Tabuchi ◽  
Hiromichi Hongo ◽  
Tetsuya Matsunaga
Keyword(s):  
Creep Strength ◽  
Steel Welds ◽  
Term Creep
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