Title page for ETD etd-05152007-131110


Document Type Master's Dissertation
Author Du Plessis, John
Email duplessisj@saiw.co.za
URN etd-05152007-131110
Document Title Control of diffusible weld metal hydrogen through arc chemistry modifications
Degree MSc (Metallurgy)
Department Materials Science and Metallurgical Engineering
Supervisor
Advisor Name Title
Prof M du Toit
Keywords
  • hydrogen
  • basicity
  • flux
  • water vapour
  • shielded metal arc welding
Date 2006-08-28
Availability unrestricted
Abstract
This project examined the feasibility of using flux modification to reduce the

as-deposited hydrogen content of basic-type shielded metal arc welds.

Additions of oxidizing ingredients (micaceous iron oxides) to the reference

flux formulation lowered the diffusible weld hydrogen content by up to 70%.

Increasing amounts of silica caused a slight reduction in hydrogen content,

probably as a result of the reaction between SiO2 and CaF2, which produces SiF4 and CaO as reaction products. Flux formulations containing additions of fluorine-containing compounds and calcite displayed lower hydrogen levels, with the diffusible weld metal hydrogen content reaching a minimum with increasing additions. Higher levels caused an increase in the weld hydrogen content. Thermodynamic slag modelling attributes the existence of these minima to a decrease in slag water capacity with an increase in slag fluorine content (at constant basicity), brought about by higher concentrations of fluorine-containing compounds in the flux

formulation. The effect of flux additions on the weld mechanical properties

and the electrode operating characteristics was not evaluated during the

course of this investigation.

Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  00dissertation.pdf 1.44 Mb 00:06:39 00:03:25 00:02:59 00:01:29 00:00:07

Browse All Available ETDs by ( Author | Department )

If you have more questions or technical problems, please Contact UPeTD.