Dissimilar metal repair welding a reactor pressure vessel mock-up with arc welding in cold metal transfer mode

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Volume Title

School of Engineering | Master's thesis

Date

2024-12-27

Department

Major/Subject

Mcode

Degree programme

Master's programme in Mechanical Engineering

Language

en

Pages

49

Series

Abstract

Nuclear power plants are getting old, and as the pressure vessels are aging, precautions are taken for possible repairs before one is actually needed. Investigating the repair welding method is the objective here. The focus in this thesis is to study whether a repair weld could be performed with an automated solution considering the following. The welding process used is gas metal arc welding in cold metal transfer mode. In addition, the repair welding filler material is different from the base material and cladding material. The repair solution in this thesis is therefore a dissimilar metal weld. Heat input restrictions are predefined from a literature review containing simulations about this topic, which is working as a guide.

Ydinvoimalaitokset vanhenevat ja sen myötä reaktoripaineastioiden ikääntyminen kovissa olosuhteissa edistää niiden haurastumista. Tavoitteena on tutkia käytännön korjaushitsauksen ratkaisua automatisoidulla hitsauskuljettimella. Fokuksena on tutkia korjaushitsauksen toteuttamista kaarihitsausprosessilla, jolla on pienempi lämmöntuonti. Menetelmänä käytetään GMAW-hitsausprosessia Cold Metal Transfer -metallinsiirtotilassa. Korjaushitsauksessa käytettävä nikkelipohjainen ruostumaton teräs -lisäaine luo eriparimetalliliitoksen austeniittisen ruostumattoman teräspinnoiteen ja rakenteellisen perusaineen ferriittisen teräksen kanssa.

Description

Supervisor

Virkkunen, Iikka

Thesis advisor

Virkkunen, Iikka

Keywords

repair weld, welding automatization, cold metal transfer, gas metal arc welding, reactor pressure vessel, microstructural characterization

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