Hot rolled steel failure analysis.

[LASERNINJA]

I am a independent laser mechanic. I have a client that cuts commercial saw blades. In the past they have machined the teeth out of the stock material. Recently they have been cutting the saws on the laser. The problem is, sometimes, they have a 90% failure rate. The teeth of the saw blade break off right at the shoulder of the tooth.

Is there someone who can recommend a consulting company to look at this problem. It is my feeling that the blade is becoming tempered by the laser and causing a brittle zone where the cracks form and propagate.

Or any thoughts in general would be great.

p.s. I have posted this else where on this site. Its a complicated problem and someone with different experience may be able to help

 

[3903KG]

I dont realy get it. does it break because of the heat?

 

[10600nm]

HAZ (Heat Affected Zone) usually is about 1 mm (0.039") in both sides from seam in the cause of laser welding, and about 0.5 mm (0.020") from edge in the cause of laser cutting.

It is hardly imaginable that laser cutting may be cause of sow blade teeth tempering to become brittle.

To be honest, in my 25 years of love (and employment) with lasers I had newer see such a problem.

With all my respect, will you ask your client where from raw material has been purchased? Is this a cheapest (among chip) CRS with unknown carbon and phosphorus content? What does your client cuts: iron wood or armor plates for steamship “Merrimac”?

Sincerely Yours,
10600nm

 

[krugtech]

I'm a little curious, are you cutting the material with N2 or O2?

Chris Krug

http://krugtech.com/

 

[LASERNINJA]

This is kind of an older post. The customer hasn't resolved the issue, at least not that I know of, I haven't heard from them in a while.

But... The reason I posted it here when I did, is because, from what they have said, they same material use to be cut on a machining center of some sort, and now that they have the laser they cut them on there. They claim that the machined saw blades have an almost non existent failure rate. The laser cut blades, the opposite.

To answer the questions, the cut with N2 and the material specification is for a higher carbon steel than your standard HRS. But exactly what the ratio is, I'm not sure.

3903KG, That is the question. I don't know if it breaks from the heat. Everyone I have talked to about this doesn't think so, but That is really the only difference between the two blades, one with high failure rate and the other with almost none.