Assessment of Weld Heat-Affected Zones in a Reactor Vessel Material

1978 ◽  
Vol 100 (3) ◽  
pp. 267-271 ◽  
Author(s):  
T. U. Marston ◽  
W. Server
Keyword(s):  
Mechanical Properties ◽  
Base Material ◽  
Charpy Impact ◽  
Dynamic Fracture Toughness ◽  
Reactor Vessel ◽  
Heavy Section ◽  
Vessel Material ◽  
Submerged Arc ◽  
Weld Heat

The mechanical properties of weld heat-affected zones (HAZ’s) associated with the heavy section, nuclear quality weldments are evaluated and found to be superior to those of the parent base material. The nil ductility transition temperature (NDTT), Charpy impact and static and dynamic fracture toughness properties of a HAZ associated with a submerged arc weld and one associated with a manual metal arc weld are directly compared with those of the parent base material. It is concluded that the stigma normally associated with HAZ is not justified for this grade and quality of material and weld procedure.

An Update on the Investigation of Fracture Toughness Properties of the High Flux Reactor Vessel From Surveillance Test Campaign in 2017

2019 ◽  
Author(s):  
M. Kolluri ◽  
F. H. E. de Haan – de Wilde ◽  
H. S. Nolles ◽  
A. J. M. de Jong
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Surface ◽  
Neutron Fluence ◽  
Reactor Vessel ◽  
Surveillance Program ◽  
High Flux ◽  
High Flux Reactor ◽  
Flux Reactor ◽  
Vessel Material

Abstract The reactor vessel of the High Flux Reactor (HFR) in Petten has been fabricated from Al 5154-O alloy grade with a maximum Mg content of 3.5 wt. %. The vessel experiences large amount of neutron fluences (notably at hot spot), of the order of 1027 n/m2, during its operational life. Substantial damage to the material’s microstructure and mechanical properties can occur at these high fluence conditions. To this end, a dedicated surveillance program: SURP (SURveillance Program) is executed to understand, predict and measure the influence of neutron radiation damage on the mechanical properties of the vessel material. In the SURP program, test specimens fabricated from representative HFR vessel material are continuously irradiated in two specially designed experimental rigs. A number of surveillance specimens are periodically extracted and tested to evaluate the changes in fracture toughness properties of the vessel as function neutron fluence. The surveillance testing results of test campaigns performed until 2015 were published previously in [1, 2]. The current paper presents fracture toughness and SEM results from the recent surveillance campaign performed in 2017. The fracture toughness specimen tested in this campaign received a thermal neutron fluence of 13.56 x1026 n/m2, which is ∼8.9 × 1025 n/m2 more than the thermal fluence received by the specimen tested in SURP 2015 campaign. These results from this campaign have shown no change in the fracture toughness from the values measured in the previous SURP campaign. The SEM observations are performed to study the fracture surface, to measure (by WDS) the transmutation Si formed near crack tip and to investigate various inclusions in the microstructure. SEM fracture surface investigation revealed a tortuous (bumpy) fracture surface constituting micro-scale dimples over majority of the fracture area. Islands of cleavage facets and secondary cracks have been observed as well. EDS analysis of various inclusions in the microstructure revealed presence of Fe rich inclusions and Mg-Si rich precipitates. Additionally, inclusions rich in Al-Mg-Cr-Ti were identified. Finally, changes in mechanical properties of Al 5154-O alloy with an increase in neutron fluence (or transmutation Si) are discussed in correlation with SEM microstructure and fracture morphology observed in SEM. TEM investigation of precipitate microstructure is ongoing and those results will be published in future.

scholarly journals Solid-state welding of ultrafine grained copper rods

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
Łukasz Morawiński ◽  
Cezary Jasiński ◽  
Marta Ciemiorek ◽  
Tomasz Chmielewski ◽  
Lech Olejnik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Contact Surface ◽  
Base Material ◽  
Low Energy ◽  
Direct Drive ◽  
Ultrafine Grained ◽  
Rotary Friction Welding ◽  
Machine Parts ◽  
Welding Pressure

AbstractThe article focuses on the Direct Drive Rotary Friction Welding of ultrafine-grained copper rods, which feature increased mechanical properties and good electrical properties, yet are limited in size. The use of UFG metals is often limited by the too small dimensions of semi-finished elements produced by SPD methods. Therefore, the production of finished machine parts from UFG metals is currently economically unjustified. Dismissal of dimensional limitations can be done by introducing joining to technological processes. The proposed joining method does not lead to a melting of the material in the joining zone or excessive degradation of the UFG microstructure. To obtain the best results, the research used the method of low-energy welding of two kinds of specimens: with a flat or a conical contact surface. In the article, the authors present, by means of metallographic microsections and microhardness measurements, the influence of rotational speed, welding pressure and conical shape contact surface on the quality of the obtained joints. The conducted research made it possible to obtain good quality joints whose microhardness is reduced only by about 10% in comparison with the base material and the tensile strength dropped from only 397–358 MPa.

Evaluation of Irradiation Embrittlement of the Weld Metals in the Chinese RPV

2020 ◽  
Author(s):  
Yupeng Cao ◽  
Yinbiao He ◽  
Yifeng Huang ◽  
Binxi Wang ◽  
Yan Yu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Nuclear Power ◽  
Degradation Mechanism ◽  
Base Material ◽  
Charpy Impact ◽  
Tensile Tests ◽  
Irradiation Damage ◽  
Limiting Factor ◽  
Irradiation Embrittlement ◽  
Weld Metals

Abstract Reactor pressure vessel (RPV) operates under high temperatures and pressures and is exposed to relatively high neutron radiation. RPV is considered to be irreplaceable, which is the most limiting factor for the lifetime of a nuclear power plant. As the most severe ageing degradation mechanism in RPV materials, irradiation embrittlement is a major issue affecting the integrity through the service life of a RPV. Our previous paper (ASME PVP2019-93615[1]) introduced our project for assessment of irradiation embrittlement of the materials for the Chinese RPVs to verify the 60-year design life, in which the specimens made of the RPV base material manufactured in China, the SA-508 Gr.3 Cl.1 forging, and the different types of weld metals were irradiated in the high fluence engineering test reactor (HFETR). The paper analyzed extent irradiation damage of the forging in terms of mechanical properties. As another part of the project, this paper concentrates on the evaluation of the weld metals in the same project. Tensile tests, Charpy impact tests and fracture toughness tests by master curve approach were carried out for the three types of weld metals subjected to different irradiation fluences (2.6E19n/cm2, 8.9E19n/cm2). Comparison of the mechanical properties of the irradiated and the unirradiated materials is made. The irradiation resistance of the weld metals in our project is also compared with the data in the literatures.

Effect of Post Weld Heat Treatment on Weld Hardness Quality of P91 Welded Pipes

2015 ◽  
Vol 799-800 ◽  
pp. 377-381
Author(s):  
Mohd Amin Abd Majid ◽  
Muhammad Sarwar
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Residual Stresses ◽  
Weld Metal ◽  
Welded Joint ◽  
Post Weld Heat Treatment ◽  
Bead Geometry ◽  
Construction Sites ◽  
Weld Heat

Quality of a weld produced is generally evaluated by different parameters such as weld size, bead geometry, deposition rate, hardness and strength. A common problem that has been faced at the construction sites is to obtain a good welded joint having the required strength with minimal detrimental residual stresses to avoid any premature cracking due to high variation of hardness. In order to address this issue and to attain good weld quality, this study has been made to comprehend the effect of the post weld heat treatment on P91 material welds produced by TIG welding. Findings from the studies indicate that the PWHT has significant influence on the weld hardness of Alloy Steel-A335 P91 pipes. It is eminent that during cooling, after welding of P91, quenched martensite was formed in the HAZ that results in an increased hardness to an undesirable level of more than 250HB. PWHT at temperature of 760°C for 2 hours has good influence on mechanical properties as the hardness decreases and turns out to be uniformly distributed. If the PWHT is correctly carried out, the hardness of parent metals, heat affected zones and weld metal can be brought into the required limits to avoid any premature cracking due to high variation of hardness.

Change in Mechanical Properties of Weld Claddings after Cyclic Thermal Loading

2013 ◽  
Vol 586 ◽  
pp. 91-95
Author(s):  
Janette Brezinová ◽  
Anna Guzanová ◽  
Peter Balog ◽  
Ján Viňáš
Keyword(s):  
Mechanical Properties ◽  
Continuous Casting ◽  
Thermal Loading ◽  
Point Of View ◽  
Filler Materials ◽  
Layer Formation ◽  
Cyclic Thermal Loading ◽  
Casting Steel ◽  
Submerged Arc

This contribution deals with the analysis of the renovation layer quality of continuous casting steel rollers, developed through the submerged arc surfacing method (SAW). The continuous casting roller was analysed through the degradation phenomena which act during the operation. Four kinds of filler materials were used for the renovation of the worn roller. Surfacing was carried out as a three-layer in order to eliminate the need for intermediate layer formation. The quality of weld deposits was evaluated in terms of the structure and microhardness after thermal cyclic loading. The best properties showed newly developed filler material W8-WLDC8 from point of view of the microhardness.

Irradiation Induced Changes in Mechanical and Microstructural Properties of the High Flux Reactor Vessel: Update of the Results From 2014 and 2015 Surveillance Test Campaigns

2017 ◽  
Author(s):  
M. Kolluri ◽  
F. H. E. de Haan-de Wilde ◽  
H. S. Nolles ◽  
A. J. M. de Jong ◽  
F. A. van den Berg
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Neutron Fluence ◽  
Reactor Vessel ◽  
Surveillance Program ◽  
High Flux ◽  
High Flux Reactor ◽  
Operational Life ◽  
Flux Reactor ◽  
Vessel Material

The reactor vessel of the High Flux Reactor (HFR) in Petten has been fabricated from Al 5154 - O alloy grade with a maximum Mg content of 3.5 wt. %. The vessel experiences large amount of neutron fluences (notably at hot spot), of the order of 1027 n/m2, during its operational life. Substantial damage to the material’s microstructure and mechanical properties can occur at these high fluence conditions. To this end, a dedicated surveillance program: SURP (SURveillance Program) is executed to understand, predict and measure the influence of neutron radiation damage on the mechanical properties of the vessel material. In the SURP program, test specimens fabricated from representative HFR vessel material are continuously irradiated in two specially designed experimental rigs. A number of surveillance specimens are periodically extracted and tested to evaluate the changes in fracture toughness properties of the vessel as a function neutron fluence. The surveillance testing results of test campaigns performed until 2009 were already published by N. V. Luzginova et. al. [1]. The current paper presents results from the two recent surveillance campaigns performed in 2014 and 2015. The fracture toughness and tensile testing results are reported. Changes in mechanical properties of Al 5154-O alloy with an increase in neutron fluence are discussed in correlation with the irradiation damage microstructure observed in TEM and the fracture morphology observed in SEM. The HFR surveillance testing results are compared to the historically published results on irradiated aluminum alloys and conclusions about the evolution of embrittlement trends in relation with irradiation induced damage mechanisms in HFR vessel are drawn at the end.

PREDICTION OF A NEUTRON FLUENCE BY AN ULTRASONIC MEASUREMENT IN AN IRRADIATED MATERIAL USED FOR SURVEILLANCE TESTING OF AN OPERATING REACTOR

2008 ◽  
Vol 22 (11) ◽  
pp. 1063-1068
Author(s):  
SAMLAI LEE
Keyword(s):  
Impact Test ◽  
Neutron Fluence ◽  
Ultrasonic Attenuation ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Reactor Vessel ◽  
Ultrasonic Measurement ◽  
Systematic Relationships ◽  
Operating Reactor ◽  
Vessel Material

The ultrasonic attenuation versus neutron fluence relationship from Charpy impact test specimens withdrawn from an operating reactor vessel during plant outages has been evaluated in order to predict the neutron fluence through a direct attenuation measurement for a reactor vessel material irradiated by neutrons. The results showed that systematic relationships for the ultrasonic attenuation versus neutron fluence at specific operating frequencies were observed for the base and weld metal and the possibility to predict neutron fluence in a specimen, that has no information on the amount of neutron fluence, by using such a consistent relationship.

Microstructure Transformation and Mechanical Properties of X80 Large Diameter Thick Wall Induction Heating Bend for Low Temperature Service

2020 ◽  
Author(s):  
Yu Liu ◽  
Zongbin You ◽  
Lijun Yan
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Weld Metal ◽  
Acicular Ferrite ◽  
Base Material ◽  
Welding Process ◽  
Seam Weld ◽  
Bent Pipe ◽  
Low Temperature Toughness ◽  
Submerged Arc

Abstract For the requirement of pipeline station construction project, Grade X80 Longitudinally Submerged Arc Welded (LSAW) induction bend pipe 1422 mm in diameter and wall thickness greater than 25 mm have been developed for pipeline station service applications at −45 °C. The mother pipe of the bends was welded by Ni-Cr-Cu-Mo-Nb-V micro-alloyed Thermo Mechanical Control Process (TMCP) steel plates. After the heat cycle of the bent pipe manufacturing, the microstructure of the base material of the bent pipe consisted of lath bainite ferrite (LBF) and granular bainite (GB). Therefore, it can obtain high strength and excellent low temperature toughness, which can meet the requirements of the project. On the other hand, the welding of the longitudinal seam-welds of the bend mother pipe uses a typical multi-wire two-pass submerged arc welding (SAW) process, which has a large amount of welding heat input. This results in a coarse columnar weld structure with a large amount of fine acicular ferrite so that the seam weld still has a good low temperature impact toughness. However, after the thermal cycling of the bend, the acicular ferrite in the microstructure of the weld metal was greatly reduced, and the grain size was unevenly distributed, which caused the low temperature toughness of the weld metal to deteriorate significantly. In order to solve this problem, the Gleeble3500 thermal simulation test machine was used to test the phase transition critical point Ac3 of the base material and the seam weld metal of the mother pipe. In order to optimize the induction bend process parameters, the influence of heating temperature, cooling rate and tempering temperature on microstructure and mechanical properties were examined. In addition, on the basis of the existing welding process, the welding wire and flux for pipe-making seam-welding were improved, and the pipe-making welding process of the bent mother pipe was improved.

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