High-temperature short-term tensile test and creep rupture strength prediction of the T92/TP347H dissimilar steel weld joints

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.

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Study on Creep Rupture Strength of Friction Welded Super304H Steel Weld Joints

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/562/1/012011 ◽

2019 ◽

Vol 562 ◽

pp. 012011

Author(s):

Yuan Lu ◽

Debiao Li ◽

Xu Yang ◽

Mo Chen ◽

Cong Ding ◽

...

Keyword(s):

Rupture Strength ◽

Creep Rupture ◽

Steel Weld ◽

Creep Rupture Strength ◽

Weld Joints ◽

Super304h Steel

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KUBOTA ALLOY KHR35C

Alloy Digest ◽

10.31399/asm.ad.ss0753 ◽

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.

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Creep Fracture Analysis of W Strengthened 9% Cr Steel Weldment

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.154-155.1699 ◽

2010 ◽

Vol 154-155 ◽

pp. 1699-1704

Author(s):

Xue Wang ◽

Qian Gang Pan ◽

Zi Jun Liu ◽

Hui Qiang Zeng ◽

Yong Shun Tao

Keyword(s):

Arc Welding ◽

Rupture Strength ◽

Fracture Analysis ◽

Creep Rupture ◽

Creep Rupture Strength ◽

Creep Tests ◽

P92 Steel ◽

Fine Grained ◽

Weld Joints ◽

M23c6 Carbides

The creep rupture behaviour,hardness distribution and microstructure of weldment made by submerge arc welding for W strengthened P92 steel are described in this paper. The cross-weld creep tests were carried out at 923K under stresses in the ranges 130-100MPa. For stress below 120MPa, weld-joints were ruptured by the Type crack, which located in their fine-grained heat affected zone(FGHAZ)with the smallest measured cross-weld hardness. A strong drop in creep rupture strength of weldment was induced by brittle type failure. In addition to coarsening of M23C6 carbides and an equiaxed fine grains in FGHAZ, intermetallic Fe2(Mo,W)Laves phase precipitated on grain boundaries during creep is probably the significant factor caused the type failure.

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

Journal of Engineering Materials and Technology ◽

10.1115/1.2903194 ◽

1990 ◽

Vol 112 (1) ◽

pp. 99-115 ◽

Cited By ~ 4

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.

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An approach to 570 °C/105h creep rupture strength prediction and safety assessment of Grade 91 components with reduced hardness after service exposures at 530–610 °C

International Journal of Pressure Vessels and Piping ◽

10.1016/j.ijpvp.2020.104073 ◽

2020 ◽

Vol 182 ◽

pp. 104073

Author(s):

Sheng Liu ◽

Chao Yang ◽

Zhifang Peng ◽

Fangfang Peng

Keyword(s):

Safety Assessment ◽

Rupture Strength ◽

Creep Rupture ◽

Strength Prediction ◽

Creep Rupture Strength ◽

Grade 91

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Study of Creep Strength for P91 Steels after Short Term Overheating above Ac3 Temperature

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.393.94 ◽

2013 ◽

Vol 393 ◽

pp. 94-101

Author(s):

Ng Guat Peng ◽

Badrol Ahmad ◽

Mohd Razali Muhamad ◽

M. Ahadlin

Keyword(s):

High Temperature ◽

Creep Strength ◽

Rupture Strength ◽

Rupture Life ◽

Creep Rupture ◽

Tempered Martensite ◽

Short Term ◽

Creep Tests ◽

Rupture Stress ◽

Limited Creep

Advanced ferritic steels containing 9 wt% Cr are widely used in the construction of supercritical and ultra supercritical boiler components. The microstructure of the as supplied 91 materials consists of a tempered martensite matrix, a fine dispersion of intergranular chromium rich M23C6 precipitates and intragranular carbonitrides MX particles rich in V and Nb. This steel requires post weld heat treatment (PWHT) to produce a tempered microstructure after welding to develop excellent creep strength for high temperature service. Based on past experience, situations may arise whereby the components are subjected to an accidental overshoot in temperature during PWHT. The short excursion to high temperature beyond Ac3 would have resulted in the formation of deleterious phases, for example, soft α-ferrite which has poor creep strength and hard martensite which has a low toughness. In this study, the degraded specimens with soft α ferrite as a result of cooling transformation from 900°C are proven to have a limited creep rupture life where the creep rupture strength dropped remarkably after 1000 hours. As the peak temperature increased to 950°C and 1000°C, hard and brittle martensite was formed on cooling. The creep specimens were found to exhibit better creep strength; most probably the creep behavior was improved by the tempering effect at 600°C during creep tests. Nevertheless, despite the tempering which might have improved the toughness slightly, the high temperature creep rupture stress still had dropped approximately 40%, as compared to the virgin alloys in the range of rupture time from 1,000 hours to 10,000 hours.

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