According to the estimates only about 1 percent of the beam power is expended on evaporation (up to 60 % is expended on thermal conductivity and about 40% on melting). On the other hand, there are authoritative statements that almost all beam energy is expended on evaporation. Who is right? What do you think about it?
Rinat,
Weigh the parts to be welded before the operation.
Then weigh them after.
The mass difference is the evaporated portion - knowing the latent heat of evaporation of the material (eg iron is 350 kJ/mol) you can calculate how much of the laser's power was required to evaporate the material.
@Rinat Seidgazov. Electron beam welding of aluminium is routinely used in aerospace work. Evaporation of the product is negligible, as evidenced by the level of condensate on the welding chambers. Any losses of metal would be catastrophic.
Do you mean some other kind of evaporation? Flux? Beam production?
Follow up to my previous answer.
I spent some time with our EB welding team this morning asking about the problem. Apparently when EB welding was introduced, evaporation was a problem. Caused by cranking up the beam power way too high or by leaving the beam for too long on one spot on the work-piece.
The equipment suppliers adapted their software quickly to prevent this and evaporation has not been seen by the team in nearly 40 years.
Thank you so much for your opinion, James and Ian. I fully share your advice. If to follow this advice, we will get an estimate of the beam power consumption to evaporation - about 1% of the beam power. But it is necessary to recognize in this case that such a weak evaporation cannot be the cause of the effect of deep penetration under the action of high vapor pressure, as is commonly believed. This means that the widespreaded computer models of the welding process are are doubtful because they all are based on an erroneous hydrodynamic model of welding.
Recently I read in the Handbook of Laser Welding Technologies (2013) the statement (without any arguments and proof) of a well-known professor that almost all the beam energy is consumed on evaporation during laser welding.
I see that as an attempt to hide this contradiction and to veil the basic error of the hydrodynamic model of the welding process, which was firmly rooted in welding science (LW and EBW) during half a century of research.
Welding science needs a deep discussion on this issue.
Rinat Seidgazov
Good luck with your research. You clearly know how to base your work on observation and measurement and this will always make great science.
Ian
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