Mechanical Properties Distribution in Welds and Forging of VVER-1000

2009 ◽  
Author(s):  
Anna A. Chernobaeva ◽  
Natalya A. Shulgan ◽  
Yaroslav I. Shtrombakh ◽  
Tatyana I. Titova ◽  
Yury A. Nikolaev ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Weld Metal ◽  
Base Metal ◽  
Axial Direction ◽  
Testing Procedure ◽  
Bending Tests ◽  
Brittle To Ductile Transition ◽  
Conservative Estimation ◽  
Surveillance Specimens ◽  
Values Distribution

Study of weld metal and shell metal of VVER-1000 reactor is carried out. Metal of the control welded joint performed to the welds Nos. 3 and 4 and metal of the test ring of supporting shell is used. For each of the analyzed materials the bending tests of Charpy specimens are carried out according to the surveillance specimens testing procedure. Fabrication of specimens and all the tests are performed by TK “OMZ Izhora”, ltd. Leadership of the tests and assessment of brittle-to-ductile transition temperature is performed by RRC “Kurchatov Institute”. It is shown that guaranteed values of brittle-to-ductile transition temperature (TK0) for VVER-1000 pressure vessel materials (0°C for weld and −25°C for base metal [1]) are the conservative estimation of TK values obtained for all groups of the tested specimens. However in some cases such estimation is super conservative. Assessment of distribution of brittle-to-ductile transition temperature (TK) values of the weld in radial direction has shown that TK varies from layer to layer in the range from −55 to −22°C. Variations of TK values are conceivably random and not connected with changes of the chemical composition of metal. It is shown that the situation is possible when brittle-to-ductile transition temperature of “inner grooving” weld metal is higher than that of the “outer grooving” weld metal. This result should be taken into account when planning the surveillance specimens programmes. Metal of “inner grooving” should be included in surveillance specimens. While assessing the TK values distribution in axial direction it has been determined that the maximum brittle-to-ductile transition temperature is specific for the area adjacent to the line of weld-to-base metal alloying. This effect is stably observed already at a distance of 8 mm from the alloying line. Study of distribution of TK values of supporting shell metal has shown that for the analyzed supporting shell the maximum brittle-to-ductile transition temperature value corresponds to the inner side of the shell middle third, the minimum value — to the shell inner surface. On the whole, shell metal is characterized by rather low values of brittle-to-ductile transition temperature.

scholarly journals A New Method for Determining the Brittle-to-Ductile Transition Temperature of a TiAl Intermetallic

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1550
Author(s):  
Sarper Nizamoglu ◽  
Karl-Heinz Lang ◽  
Stefan Guth ◽  
Martin Heilmaier
Keyword(s):  
Transition Temperature ◽  
Charpy Impact ◽  
Plastic Strain Amplitude ◽  
Bending Tests ◽  
Brittle To Ductile Transition ◽  
Intermetallic Materials ◽  
Different Temperatures ◽  
Specific Temperature ◽  
Increasing Temperature ◽  
Fully Lamellar

Intermetallic materials typically change their deformation behavior from brittle to ductile at a certain temperature called the Brittle-to-Ductile Transition Temperature (BDTT). This specific temperature can be determined by the Charpy impact, tensile or bending tests conducted at different temperatures and strain rates, which usually requires a large number of specimens. In order to reduce the number of necessary specimens for finding the BDTT, a new methodology comprising cyclic loadings as the crucial step was studied on a fully lamellar TiAl alloy with composition Ti-48Al-2Nb-0.7Cr-0.3Si. The loading blocks are applied isothermally under strain control and repeated on the same specimen at different temperatures. The development of plastic strain amplitude with increasing temperature is analyzed to determine the BDTT of the specimen. The BDTTs found with the described method agree well with literature data derived with conventional methods. With the loading strategy presented in this study, the BDTT and additionally the effect of strain rate on it can be found by using a single specimen.

NIMROD 617KS

Alloy Digest ◽  
2002 ◽  
Vol 51 (5) ◽  
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Weld Metal ◽  
Tensile Properties ◽  
Base Metal ◽  
Heat Treating ◽  
Nominal Composition

Abstract Nimrod 617KS is an Inconel-type consumable with a nominal composition of nickel, 24% Cr,12% Co, and 9% Mo and is used to join UNS N06617 and Nicrofer 6023 to themselves. The alloy is designed for high-temperature service and is often used as the weld metal in dissimilar cases to ensure the weld is as strong as the base metal. This datasheet provides information on composition, hardness, and tensile properties as well as fracture toughness. It also includes information on heat treating and joining. Filing Code: Ni-583. Producer or source: Metrode Products Ltd.

Deformation mechanisms in MoSi2at temperatures above the brittle-to-ductile transition temperature

1997 ◽  
Vol 75 (1) ◽  
pp. 17-30 ◽  
Author(s):  
Daniel J. Evans ◽  
Frank J. Scheltens ◽  
John B. Woodhouse ◽  
Hamish L. Fraser
Keyword(s):  
Transition Temperature ◽  
Deformation Mechanisms ◽  
Brittle To Ductile Transition

scholarly journals EBSD Investigation of the Microtexture of Weld Metal and Base Metal in Laser Welded Al–Li Alloys

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2357 ◽  
Author(s):  
Li Cui ◽  
Zhibo Peng ◽  
Xiaokun Yuan ◽  
Dingyong He ◽  
Li Chen
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Transverse Section ◽  
Grain Morphology ◽  
Structural Features ◽  
Butt Joint ◽  
Horizontal Surface ◽  
Boundary Misorientation ◽  
Texture Intensity ◽  
Highly Correlated

Autogenous laser welding of 5A90 Al–Li alloy sheets in a butt-joint configuration was carried out in this study. The microstructure characteristics of the weld metal and base metal in the horizontal surface and the transverse section of the welded joints were examined quantitatively using electron back scattered diffraction (EBSD) technique. The results show that the weld metal in the horizontal surface and the transverse section exhibits similar grain structural features including the grain orientations, grain shapes, and grain sizes, whereas distinct differences in the texture intensity and misorientation distributions are observed. However, the base metal in the horizontal surface and the transverse section of the joints reveals the obvious different texture characteristics in terms of the grain orientation, grain morphology, predominate texture ingredients, distribution intensities of textures, and grain boundary misorientation distribution, resulting in the diversity of the microhardness in the base metal and the softening of the weld metal. However, the degree of the drop in the hardness of the weld metal is highly correlated to the microtexture developed in the base metal.

Predicting the Brittle-to-Ductile Transition Temperatures for Surface Cracks in Pipeline Girth Welds: It’s Better Than You Thought

2008 ◽  
Author(s):  
Gery Wilkowski ◽  
David Rudland ◽  
Do-Jun Shim ◽  
David Horsley
Keyword(s):  
Transition Temperature ◽  
Surface Crack ◽  
Master Curve ◽  
Crack Depth ◽  
Temperature Shift ◽  
Transition Temperatures ◽  
Surface Cracks ◽  
Line Pipe ◽  
Brittle To Ductile Transition ◽  
Girth Welds

A methodology to predict the brittle-to-ductile transition temperature for sharp or blunt surface-breaking defects in base metals was developed and presented at IPC 2006. The method involved applying a series of transition temperature shifts due to loading rate, thickness, and constraint differences between bending versus tension loading, as well as a function of surface-crack depth. The result was a master curve of transition temperatures that could predict dynamic or static transition temperatures of through-wall cracks or surface cracks in pipes. The surface-crack brittle-to-ductile transition temperature could be predicted from either Charpy or CTOD bend-bar specimen transition temperature information. The surface crack in the pipe has much lower crack-tip constraint, and therefore a much lower brittle-to-ductile transition temperature than either the Charpy or CTOD bend-bar specimen transition temperature. This paper extends the prior work by presenting past and recent data on cracks in line-pipe girth welds. The data developed for one X100 weld metal shows that the same base-metal master curve for transition temperatures works well for line-pipe girth welds. The experimental results show that the transition temperature shift for the surface-crack constraint condition in the weld was about 30C lower than the transition temperature from standard CTOD bend-bar tests, and that transition temperature difference was predicted well. Hence surface cracks in girth welds may exhibit higher fracture resistance in full-scale behavior than might be predicted from CTOD bend-bar specimen testing. These limited tests show that with additional validation efforts the FITT Master Curve is appropriate for implementation to codes and standards for girth-weld defect stress-based criteria. For strain-based criteria or leak-before-break behavior, the pipeline would have to operate at some additional temperature above the FITT of the surface crack to ensure sufficient ductile fracture behavior.

scholarly journals Continuous Cooling Transformation Diagrams of 2.25Cr-1Mo-0.25V Submerged-Arc Weld Metal and Base Metal

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1055
Author(s):  
Hannah Schönmaier ◽  
Bernd Loder ◽  
Thomas Fischer ◽  
Fred Grimm ◽  
Ronny Krein ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Weld Metal ◽  
Base Metal ◽  
Lower Bainite ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Upper Bainite ◽  
Cct Diagrams ◽  
Scanning Electron

The transformation behavior and microstructural evolution during continuous cooling within the heat affected zone between the weld beads of a 2.25Cr-1Mo-0.25V all-weld metal and the corresponding 2.25Cr-1Mo-0.25V base metal were investigated by means of dilatometer measurements, optical and scanning electron microscopy. Furthermore, macro-hardness measurements were conducted and the ferrite phase fraction was analyzed from optical microscopic images using an imaging processing program. Thereupon a continuous cooling transformation (CCT) diagram for the 2.25Cr-1Mo-0.25V base metal and three welding CCT diagrams with different peak temperatures were constructed to realistically simulate the temperature profile of the different regions within the heat affected zones between the weld beads of the multi-layer weld metal. The microstructural constituents which were observed depending on the peak temperature and cooling parameters are low quantities of martensite, high quantities of bainite and in particular lower bainite, coalesced bainite and upper bainite as well as ferrite for the welding CCT diagrams. Regarding the base metal CCT diagram, all dilatometer specimens exhibited a fully bainitic microstructure consisting of lower bainite, coalesced bainite and upper bainite. Only the slowest cooling rate with a cooling parameter of 50 s caused a ferritic transformation. Nevertheless, it has to be emphasized that the distinction between martensite and bainite and the various kinds of bainite was only possible at higher magnification using scanning electron microscopy.

scholarly journals The Increase in a Brittle-to-ductile Transition Temperature in Fe–Al Single Crystals

2011 ◽  
Vol 51 (6) ◽  
pp. 999-1004 ◽  
Author(s):  
Masaki Tanaka ◽  
Keiki Maeno ◽  
Kenji Higashida ◽  
Masahiro Fujikura ◽  
Kohsaku Ushioda
Keyword(s):  
Transition Temperature ◽  
Single Crystals ◽  
Brittle To Ductile Transition

Investigation of the Beltline Welding Seam and Base Metal of the Greifswald WWER-440 Unit 1 Reactor Pressure Vessel

2009 ◽  
Author(s):  
Jan Schuhknecht ◽  
Hans-Werner Viehrig ◽  
Udo Rindelhardt
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Pressure Vessel ◽  
Master Curve ◽  
Reactor Pressure Vessel ◽  
Reference Temperature ◽  
Metal Ring ◽  
Welding Seam ◽  
Root Region ◽  
Reactor Pressure

The investigation of reactor pressure vessel (RPV) materials from decommissioned NPPs offers the unique opportunity to scrutinize the irradiation behaviour under real conditions. Material samples taken from the RPV wall enable a comprehensive material characterisation. The paper describes the investigation of trepans taken from the decommissioned WWER-440 first generation RPVs of the Greifswald NPP. Those RPVs represent different material conditions such as irradiated (I), irradiated and recovery annealed (IA) and irradiated, recovery annealed and re-irradiated (IAI). The working program is focussed on the characterisation of the RPV steels (base and weld metal) through the RPV wall. The key part of the testing is aimed at the determination of the reference temperature T0 following the ASTM Test Standard E1921-05 to determine the fracture toughness of the RPV steel in different thickness locations. In a first step the trepans taken from the RPV Greifswald Unit 1 containing the X-butt multilayer submerged welding seam and from base metal ring 0.3.1 both located in the beltline region were investigated. Unit 1 represents the IAI condition. It is shown that the Master Curve approach as adopted in ASTM E1921 is applicable to the investigated original WWER-440 weld metal. The evaluated T0 varies through the thickness of the welding seam. The lowest T0 value was measured in the root region of the welding seam representing a uniform fine grain ferritic structure. Beyond the welding root T0 shows a wavelike behaviour. The highest T0 of the weld seam was not measured at the inner wall surface. This is important for the assessment of ductile-to-brittle temperatures measured on sub size Charpy specimens made of weld metal compact samples removed from the inner RPV wall. Our findings imply that these samples do not represent the most conservative condition. Nevertheless, the Charpy transition temperature TT41J estimated with results of sub size specimens after the recovery annealing was confirmed by the testing of standard Charpy V-notch specimens. The evaluated Charpy-V TT41J shows a better accordance with the irradiation fluence along the wall thickness than the Master Curve reference temperature T0. The evaluated T0 from the trepan of base metal ring 0.3.1 varies through the thickness of the RPV wall. T0 increases from −120°C at the inner surface to −104°C at a distance of 33 mm from it and again to −115°C at the outer RPV wall. The KJc values generally follow the course of the MC, although the scatter is large. The re-embrittlement during 2 campaigns operation can be assumed to be low for the weld and base metal.

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