scholarly journals Effect of Notches on the Creep-Rupture Strength and Fatigue Strength at High Temperature

1963 ◽  
Vol 12 (114) ◽  
pp. 123-129 ◽  
Author(s):  
Daizo SUNAMOTO ◽  
Masaharu FUJIWARA
Keyword(s):  
High Temperature ◽  
Fatigue Strength ◽  
Rupture Strength ◽  
Creep Rupture ◽  
Creep Rupture Strength

KUBOTA ALLOY KHR35C

Alloy Digest ◽  
1999 ◽  
Vol 48 (7) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Rupture Strength ◽  
Creep Rupture ◽  
Creep Rupture Strength ◽  
Temperature Performance

Abstract Kubota alloy KHR35C is similar to HP alloy with the addition of niobium to increase its creep-rupture strength. Typical applications include components and assemblies for severe carburizing environments, such as ethylene pyrolysis coils. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as casting and joining. Filing Code: SS-753. Producer or source: Kubota Metal Corporation.

Progress in the Design of an Improved High-Temperature 1 Percent CrMoV Rotor Steel

1990 ◽  
Vol 112 (1) ◽  
pp. 99-115 ◽  
Author(s):  
R. L. Bodnar ◽  
J. R. Michael ◽  
S. S. Hansen ◽  
R. I. Jaffee
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Room Temperature ◽  
Rupture Strength ◽  
Temper Embrittlement ◽  
Creep Rupture ◽  
Rotor Steel ◽  
Creep Rupture Strength ◽  
Austenitizing Temperature ◽  
Creep Ductility

Silicon-deoxidized, tempered bainitic 1 percent CrMoV steel is currently used extensively for high-temperature steam turbine rotor forgings operating at temperatures up to 565°C due to its excellent creep rupture properties and relative economy. There is impetus to improve the creep rupture strength of this steel while maintaining its current toughness level and vice versa. The excellent creep rupture ductility of the low Si version of this steel allows the use of a higher austenitizing temperature or tensile strength level for improving creep rupture strength without loss in creep ductility or toughness. When the tensile strength of this steel is increased from 785 to 854 MPa, the creep rupture strength exceeds that of the more expensive martensitic 12CrMoVCbN steel currently used for high-temperature rotor applications where additional creep rupture strength is required. The toughness of 1 percent CrMoV steel is improved by lowering the bainite start (Bs) temperature in a “superclean” base composition which is essentially free of Mn, Si, P, S, Sb, As and Sn. The Bs temperature can be lowered through the addition of alloying elements (i.e., C, Ni, Cr, and Mo) and/or increasing the cooling rate from the austenitizing temperature. Using these techniques, the 50 percent FATT can be lowered from approximately 100°C to below room temperature, which provides the opportunity to eliminate the special precautionary procedures currently used in the startup and shutdown of steam turbines. The most promising steels in terms of creep rupture and toughness properties contain 2.5 percent Ni and 0.04 percent Cb (for austenite grain refinement and enhanced tempering resistance). In general, the creep rupture strength of the superclean steels equals or exceeds that of the standard 1 percent CrMoV steel. In addition, the superclean steels have not been found to be susceptible to temper embrittlement, nor do they alter the room temperature fatigue crack propagation characteristics of the standard 1 percent CrMoV steel. These new steels may also find application in combination high-temperature-low-temperature rotors and gas turbine rotors.

Evaluation of Short Term Creep-Rupture Strength of High Temperature P122 Boiler Material

2003 ◽  
Author(s):  
John Pumwa
Keyword(s):  
High Temperature ◽  
Fracture Mode ◽  
Life Prediction ◽  
Rupture Strength ◽  
Creep Rupture ◽  
Creep Rupture Strength ◽  
Short Term ◽  
Boiler Material ◽  
Term Creep ◽  
Short Term Creep

The complex thermal-mechanical loading of power-generating plant components usually comprises of creep, high-cycle and low-cycle fatigue which are thermally induced by start-ups, load changes and shut-downs, producing instationary temperature gradients and hence creating strain as well as stress fields. In order to select the correct materials for these hostile environmental conditions, it is vitally important to understand the behaviour of mechanical properties such as creep rupture properties of these materials. This paper reports the results of standard creep rupture tests of P122 (HCM12A or 12Cr-1.8W-1.5Cu) high temperature boiler material. P122 is one of the latest developed materials for high temperature environments, which has the potential to be successful in hostile environments. The tests were conducted at temperatures ranging from 550°C to 700°C at 50°C intervals with stress levels ranging from 80–400 MPa using a locally made creep rupture testing machine. The results are found to have stable creep-rupture strength at short term creep stage for over 800-hours at elevated temperatures. Creep life prediction from Larson-Miller relationship was also carried out and the accuracy of life prediction is demonstrated. Moreover, the fracture mode assessments strongly revealed a typical ductile transgranular fracture mode with dimples and voids.

Development of Materials and Coating Processes for High Temperature Heavy Duty Gas Turbines

1990 ◽  
Author(s):  
S. Nakamura ◽  
Y. Fukui ◽  
Y. Kojima ◽  
M. Siga ◽  
S. Yamaguchi
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Rupture Strength ◽  
Chemical Vapor ◽  
Creep Rupture ◽  
Internal Cooling ◽  
Creep Rupture Strength ◽  
Heavy Duty ◽  
Corrosion Properties ◽  
Turbine Disc

This paper describes materials developed for the first stage nozzle and all stages turbine disc, and the new coating processes of the first stage bucket for high temperature, heavy duty gas turbines. A cobalt base casting superalloy (30Cr-10Ni-7W-0.2Nb-0.15Zr-0.2Ti-bal.Co), having high creep rupture strength and ductility, was used for the first stage nozzle and 12Cr forging material, having high creep rupture strength, was used for all stages turbine disc of the high temperature, heavy duty gas turbine, the H25. To increase hot corrosion properties of the first stage bucket, MCrAlY was applied on the bucket external surfaces by a low-pressure plasma-spray coating technique. A procedure of chemical vapor deposition for Al coating on the bucket internal cooling paths was also established for future high temperature gas turbines.

Cold Work Effect on Creep Rupture Strength of Austenitic Boiler Steels

2007 ◽  
Author(s):  
Fujimitsu Masuyama
Keyword(s):  
High Temperature ◽  
Creep Strength ◽  
Rupture Strength ◽  
Cold Work ◽  
Creep Rupture ◽  
Austenitic Steels ◽  
Chemical Compositions ◽  
Creep Rupture Strength ◽  
Cold Worked

In order to clarify the effect of cold work, warm work at working temperatures of up to 400°C and chemical compositions on the creep rupture strength of austenitic steels used for boiler tubing and high temperature support structures, long-term creep rupture tests were carried out on typical 18Cr-8Ni system steels consisting of TP304H, TP316H, TP321H and TP347H grade tubes and of TP321 plates. The long-term (100,000 hours) creep rupture strength of these steels was evaluated in terms of working ratio and Ni-equivalent. It was consequently clarified that creep rupture strength was substantially reduced in the cold-worked TP321 and TP321H materials, although warm-work resulted in less work-induced deterioration. It was also found creep rupture strength was enhanced by the higher Ni-eq in 18Cr-8Ni austenitic steels, and that the combined conditions of working ratio and Ni-eq govern the creep rupture strength criteria of weaker or stronger than as-received strength. Additionally the effect of cold work on the creep rupture strength and ductility of recently developed creep-strength enhanced 23Cr austenitic stainless steel (a candidate material for the hot end of superheaters in ultra-high temperature fossil-fired power plants) was considered. The strength of cold worked 23Cr austenitic steel was observed to fall below the as-received strength at stresses within about 120MPa, while re-solution annealing recovered the creep strength level to the as-received strength across the entire stress region.

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