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Electron beam and thermit welding
The document discusses two welding processes: electron beam welding and thermit welding. Electron beam welding uses a concentrated beam of electrons to melt and fuse base metals in a vacuum chamber, allowing for high purity welds of dissimilar metals. However, it has high costs and downtime for pumping the vacuum chamber. Thermit welding uses an exothermic reaction between aluminum and a metal oxide to produce enough heat to melt metals for welding without external energy. The reaction separates into a superheated metal and aluminum oxide slag. Thermit welding is used to join shafts, railway tracks, and machinery frames.
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Electron beam and thermit welding
- 1. MANUFACTURING TECHNOLOGY –I CRAFTED BY: RAMESH KUMAR A ASSISTANT PROFESSOR SONA COLLEGE OF TECHNOLOGY SALEM 07-02-2019 05:39 1
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- 4. ELECTRON BEAM WELDING… In this process a concentrated beam of electrons bombards the base metal, causing it to melt and fuse The process is most efficient when done in a vacuum Therefore the size of the vacuum chamber limits the size of the work pieces that can be welded Advantages extremely high purity dissimilar metals depths as great as 150mm Disadvantages High cost Time lost in pumping out the vacuum chamber between welds Applications Space industry Aircraft manufacturing 07-02-2019 05:39 4
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- 8. THERMIT WELDING… Terminology Crucible: the thermit chemical reaction takes place in a vessel called a crucible Mixture: A mixture of finely divided aluminum, metal oxide with the addition of any required alloying metals Mould: This is a mould that is formed around parts that need to be welded. The mode receives the molten metal Reaction: The chemical reaction between aluminum and metal oxide. The reaction produces an aluminum oxide slag and superheated molten metal 07-02-2019 05:39 8
- 9. THERMIT WELDING… Fusioncreated by a chemical reaction that occurs due to the difference of free energy between aluminium and metal oxide This difference produces enough heat to produce liquid steel or any other metal and allow without applying outside energy Once the reaction is initiated by an external heat source, the aluminum reduces the oxygen from the metal-oxide, which will result in a liquid superheated aluminum-oxide (Al2O3) Since these two components are different in density, they separate automatically and the liquid metal can be used for the production of alloys, special metals or for multiple welding applications Applications Joining or repair of shafts Rails of railway tracks Machinery frames 07-02-2019 05:39 9
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