Using Lasers to Melt Steel

CO2 Lasers are commonly used to melt metal in industrial settings. The pinpoint accuracy can be used to weld metal components together, particularly small and irregular shapes. Using galvo mirrors the beam can be moved with precision to produce a high quality weld that would be extremely difficult to produce any other way. YAG Lasers generally do not have sufficient power for this purpose, but are great for etching symbols, serial numbers, etc. into metal components, and for cutting thin material. And of course HeNe lasers are commonly used as barcode readers. I have not worked with the other types of lasers, so will not comment on them.

"a lot of temperature, but not a large enough amount of heat!"

This statement is quite interesting, is the amount of heat required related to the maximum power supplied by laser or to properties of light to penetrate steel? The idea is not to produce "laser blast furnace" as such, but more to understand process of melting steel with light source/laser/solar radiation; convection process, radiation process, heat transfer within the steel induced by laser etc....

Hi! The heat transfer in laser melting, cutting, weilding, etc is through radiation on the surface and thereafter below the surface through conduction, until the melt pool forms after which it is through convection.

Mustafa

If you are interested in iron and steel making the best place to start might be "Making, Shaping and Treating of Steel" published initially by United States Steel Corporation. [Not sure who has the rights to publish this tome at present]. You should be able to find most information about Blast Furnace heat transfer and heat transfer in steel and steel processing in this volume.

Any idea of what kind of losses occur due to reflection of laser beam. Presumably molten metal is silvery in colour and highly reflective??

Absorption and reflection of a laser are wave length dependant for each material.

A laser that cuts diamond may be reflected by glass (just an example).

Angle of incidence is important also on some materials.

Unlike cutting, melting does not usually have problems with ejected plasma.

Lasers should let you do some very fast and precise measurements of puddle and heat propagation.

I haven't played with them since the late 80's early 90's

Brad

Yes, reflection is a problem. When laser etching, a black, heat absorbent mask is applied to many materials that otherwise would simply reflect the beam.

The more the reflection the less energy transfer, hence less temperature!!!

Induction works very well in the foundry. We love good light as long as it doesn't contribute to light pollution. Be respectful and shine! Don't break it if its not fixable.

Apparently laser are used to harden the surface of the steel, radiation from laser melts surface of the steel and the moment laser is switched off surface cools rapidly by heat transfer into the air (conduction?), this process freezes crystal structure in martensitic state. Would you need to heat furnace/environment/refractories to same degree to proceed with full melting???