Causes of heat-to-heat variation of creep strength in grade 91 steel

2017 ◽  
Vol 696 ◽  
pp. 104-112 ◽  
Author(s):  
K. Maruyama ◽  
J. Nakamura ◽  
N. Sekido ◽  
K. Yoshimi
Keyword(s):  
Creep Strength ◽  
Grade 91 ◽  
Grade 91 Steel

EPRI Guidelines for Fabrication of Components Manufactured From Grade 91 Steel

2012 ◽  
Author(s):  
Jonathan Parker ◽  
Kent Coleman
Keyword(s):  
Quality Assurance ◽  
Creep Strength ◽  
Ferritic Steels ◽  
Factors Affecting ◽  
Critical Information ◽  
Grade 91 ◽  
Recommended Guidelines ◽  
Grade 91 Steel

Over the last 10 years EPRI has been researching critical information on the factors affecting the performance of creep strength enhanced ferritic steels in general and Grade 91 steel in particular. This work has resulted in a major new report which provides recommended guidelines for fabrication and the associated quality assurance to ensure that component properties meet or exceed the minimum expectations of ASME design approaches. The present paper outlines the recommendations in the report and provides technical background for specific aspects of the guide.

Re-Evaluation of Long-Term Creep Strength of Welded Joint of ASME Grade 91 Type Steel

2016 ◽  
Author(s):  
Masatsugu Yaguchi ◽  
Kaoru Nakamura ◽  
Sosuke Nakahashi
Keyword(s):  
Creep Strength ◽  
Welded Joints ◽  
Rupture Strength ◽  
Creep Rupture ◽  
Base Metals ◽  
Rupture Data ◽  
Grade 91 ◽  
Term Creep ◽  
Grade 91 Steel

Creep rupture data of welded joints of ASME Grade 91 type steel have been collected from Japanese plants, milling companies and institutes, and the long-term creep rupture strength of the material has been evaluated. This evaluation of welded joints of Grade 91 steel is the third one in Japan as similar studies were conducted in 2004 and 2010. The re-evaluation of the creep rupture strength was conducted with emphasis on the long-term creep rupture data obtained since the previous study, with durations of the new data of up to about 60000h. The new long-term data exhibited lower creep strength than that obtained from the master creep life equation for welded joints of Grade 91 steel determined in 2010, then the master creep life equation was again reviewed on the basis of the new data using the same regression method as that used in 2010. Furthermore, the weld strength reduction factors obtained from 100000h creep strength of welded joints and the base metals are given as a function of temperature, where the master creep equations of the base metals are also redetermined in this study.

Improvement of High Temperature Creep Strength of Conventional Grade 91 Steel by Thermomechanical Treatments

2019 ◽  
Author(s):  
Rebeca Hernández ◽  
Marta Serrano ◽  
Andrea García-Junceda ◽  
Elvira Oñorbe ◽  
Javier Vivas
Keyword(s):  
Thermomechanical Treatment ◽  
Creep Strength ◽  
Rupture Life ◽  
Constant Load ◽  
Creep Properties ◽  
The Matrix ◽  
The Common ◽  
Grade 91 ◽  
Different Levels ◽  
Grade 91 Steel

Abstract The study of the enhanced creep strength of conventional ferritic-martensitic (F/M) grade 91 steel by a thermomechanical treatment (TMT) to increase the precipitation of MX particles in the matrix was performed. Creep properties were evaluated by tests at constant load at temperatures that varied from 600 °C to 700 °C with different levels of stress for both steels: T91 and T91-TMT. The creep curves and main parameters for both steels in the different conditions were analysed. Results show a great improvement of creep strength of the T91 after the thermomechanical treatment in comparison with the conventional steel. T91-TMT presents a rupture life significantly higher than T91 and a decrease of the values of the minimum creep rate. An increase of the density of MX precipitates in the matrix of the T91-TMT due to the thermomechanical treatment in comparison with T91 can be also observed. A change in the fractography was also detected. T91-TMT specimens showed signs of brittle fracture instead of the ductile fracture, with the common necking effect detected in the T91.

Effect of Aging on Creep Strength of Grade 91 Steel Weld Metal

2016 ◽  
Vol 2016 (0) ◽  
pp. J0310203
Author(s):  
Sosuke NAKAHASHI ◽  
Masatsugu YAGUCHI ◽  
Koji TAMURA ◽  
Yusuke MINAMI
Keyword(s):  
Weld Metal ◽  
Creep Strength ◽  
Steel Weld ◽  
Steel Weld Metal ◽  
Grade 91 ◽  
Grade 91 Steel

The creep strength of aberrant grade 91 steel

2021 ◽  
pp. 1-5
Author(s):  
Stephen James Brett ◽  
Alex Bridges ◽  
Daniel Purdy
Keyword(s):  
Creep Strength ◽  
Grade 91 ◽  
Grade 91 Steel

scholarly journals Estimation of Creep Strength of Grade 91 Steel Welded Joint in Time Region Over 100,000 Hours

2018 ◽  
Author(s):  
Masatsugu Yaguchi ◽  
Sosuke Nakahashi ◽  
Koji Tamura
Keyword(s):  
Creep Strength ◽  
Welded Joints ◽  
Welded Joint ◽  
Base Metals ◽  
Creep Life ◽  
Initial State ◽  
Creep Tests ◽  
Grade 91 ◽  
Grade 91 Steel

A creep strength of welded joint of ASME Grade 91 steel in a region exceeding 100,000 hours was examined in this work. Creep tests were conducted on the steel used at USC plants for long-term, and remaining creep life of the material for operating condition was calculated on a fitting curve using Larson-Miller parameter. Total creep life of the material, which means a creep life at initial state, was presumed to be a summation of the service time at the plants and the remaining creep life. The estimation was conducted for welded joints used at five plants for long-term, and all results lay within 99% confidential band by the creep life evaluation curve of the material proposed by Japanese committee in 2015, while a significant heat-heat variation of creep strength was found even in the region exceeding 100,000 hours. Creep tests on base metals related to each welded joint were also conducted, and the estimation results of the total creep life of the base metals were compared to those of the welded joints. It was suggested that the heat-heat variation of the welded joints eminently depends on the creep life property of the corresponding base metal.

Microstructural stability and long term creep strength of grade 91 steel

2009 ◽  
Vol 4 (4) ◽  
pp. 176-183 ◽  
Author(s):  
K Kimura ◽  
K Sawada ◽  
H Kushima ◽  
Y Toda
Keyword(s):  
Creep Strength ◽  
Microstructural Stability ◽  
Grade 91 ◽  
Term Creep ◽  
Grade 91 Steel

Correlation of Plain and Notched Bar Creep Behavior in Grade 91 Steel

2019 ◽  
Author(s):  
Yukio Takahashi ◽  
Haruhisa Shigeyama ◽  
John Siefert
Keyword(s):  
Creep Behavior ◽  
Creep Strength ◽  
Rupture Strength ◽  
Material Behavior ◽  
Creep Rupture Strength ◽  
Creep Tests ◽  
Grade 91 ◽  
Different Characteristics ◽  
Strength And Ductility ◽  
Grade 91 Steel

Abstract Axi-symmetrical notched bar specimens are often used as a means of evaluating the effect of stress multiaxiality on material behavior under various loading conditions in a relatively easy way. In order to understand the possible correlation existing between plain and notched bar creep behavior of various materials with different characteristics, creep tests were systematically performed at 625°C for plain and notched bar specimens made from 6 heats of Grade 91 steel. They showed a wide variety in terms of creep rupture strength as well as in ductility when tested in a form of plain bar but also in notched bar to a larger extent. Strong similarities were found between the heat-dependency of creep strength and ductility of plain bar and notched bar specimens. Possibility of estimating notched bar behavior from the information obtained by plain bar tests was shown.

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