Overview of Welding Research Under the New Nuclear Manufacturing (NNUMAN) Programme

2014 ◽  
Author(s):  
B. Jeyaganesh ◽  
M. D. Callaghan ◽  
J. A. Francis ◽  
P. D. English ◽  
A. Vasileiou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Numerical Models ◽  
Welding Process ◽  
High Energy ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Reactor Pressure Vessel Steel ◽  
Manufacturing Technologies ◽  
Welding Processes

The New Nuclear Manufacturing (NNUMAN) programme was established in the UK in late 2012, to develop new manufacturing technologies for nuclear components. One of the themes of this programme is research to develop candidate advanced joining methods using arc and high-energy welding processes, for components manufactured using nuclear grade reactor pressure vessel steel SA508 Grade 3 Class 1. The key outcomes of this study are the comparison of residual stresses and mechanical properties of welded mock-ups as a function of different welding processes, together with the development and validation of numerical models to predict residual stresses and mechanical properties. This paper gives an overview of the NNUMAN welding programme, coupled with design of experiments to date. The ultimate objective of this research is aimed at determining the effect of the selection of welding process, on the performance of nuclear components with operational lifetimes of 60 years or greater.

Evaluation of through-thickness residual stresses and microstructure in SA516 Gr. 70 steel welds

2021 ◽  
pp. 095440542199012
Author(s):  
Pradeeptta Kumar Taraphdar ◽  
Manas Mohan Mahapatra ◽  
Arun Kumar Pradhan ◽  
Pavan Kumar Singh ◽  
Kamal Sharma ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Nuclear Power ◽  
Three Dimensional ◽  
Welding Process ◽  
Influential Factors ◽  
Stress Fields ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Steel Welds

The critical working condition of nuclear power plant equipment necessitates meticulous determination of the welding process and parameters. In this work, some major influential factors of welding were investigated to observe their effects on the through-thickness residual stress distribution in multipass pressure vessel steel welds. In this regard, experiments were conducted to find the characteristics of residual stresses dispersed in SA516 Grade 70 steel welds of different groove geometries with distinct welding conditions. Three-dimensional finite element models of the weldments were developed considering a moving heat source with temperature-dependent material properties to simulate the welding thermal cycles and corresponding residual stress fields. Effects of weld groove geometry, number of weld passes, external constraints, and preheating on the through-thickness residual stress fields were studied. Additional attention was given to the evaluation of the heterogeneous microstructure and microhardness across the weld cross-section associated with their weld thermal history. Finally, the evolution of the through-thickness residual stresses attributed to subsequent weld passes was elaborated.

scholarly journals Comprehensive Analysis of the Microstructure and Mechanical Properties of Friction-Stir-Welded Low-Carbon High-Strength Steels with Tensile Strengths Ranging from 590 MPa to 1.5 GPa

2021 ◽  
Vol 11 (12) ◽  
pp. 5728
Author(s):  
HyeonJeong You ◽  
Minjung Kang ◽  
Sung Yi ◽  
Soongkeun Hyun ◽  
Cheolhee Kim
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Joint Strength ◽  
Solid Phase ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
Friction Stir ◽  
Welding Processes

High-strength steels are being increasingly employed in the automotive industry, requiring efficient welding processes. This study analyzed the materials and mechanical properties of high-strength automotive steels with strengths ranging from 590 MPa to 1500 MPa, subjected to friction stir welding (FSW), which is a solid-phase welding process. The high-strength steels were hardened by a high fraction of martensite, and the welds were composed of a recrystallized zone (RZ), a partially recrystallized zone (PRZ), a tempered zone (TZ), and an unaffected base metal (BM). The RZ exhibited a higher hardness than the BM and was fully martensitic when the BM strength was 980 MPa or higher. When the BM strength was 780 MPa or higher, the PRZ and TZ softened owing to tempered martensitic formation and were the fracture locations in the tensile test, whereas BM fracture occurred in the tensile test of the 590 MPa steel weld. The joint strength, determined by the hardness and width of the softened zone, increased and then saturated with an increase in the BM strength. From the results, we can conclude that the thermal history and size of the PRZ and TZ should be controlled to enhance the joint strength of automotive steels.

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