Bad steel on a Stihl bar??

[Ed*L]

Update:
I was at a customers yesterday, they just happen to have a Metalurgist on site. He was nice enough to put the bar under the microscope & take a look at it. He had no explanation for the "pitting", but came to the conclusion there was paint in the pits.
Stopped at the Stihl dealer after work & looked at some of the new bars they had. All of them had the same rough surface, it was hard to tell if they were as bad as mine because of the paint on them.
We came to the conclusion the the rough surface is from the laser used to cut the bar out. Apparently Stihl is no longer grinding the top of the rails on the bar.
It should smooth up after I dress the bar a couple of times.

Ed

 

[bwalker]

Work hardening involves the material being displaced, not just loaded or heated. Try again.

Thats not exactly true. For instance steel can be work hardened by shot peening. Wouldnt shot peening and a chain smacking into the bar repeadtly have the same effect? Keep in mind that the chains tooth is constantly rocking back and forth as it takes bites of wood thus smacking the chain against the bar rails over and over at high frequancy.

 

[bump_r]

I think work hardening and shot-peining are related, one being a surface treatment and the other being deeper; I just don't see it as a planned treatment.

Either way, if the surface condition is considered "normal" and has yet to show ill effects, what the hey. Good discussion, though.

 

[WRW]

Update:
I was at a customers yesterday, they just happen to have a Metalurgist on site. He was nice enough to put the bar under the microscope & take a look at it. He had no explanation for the "pitting", but came to the conclusion there was paint in the pits.
Stopped at the Stihl dealer after work & looked at some of the new bars they had. All of them had the same rough surface, it was hard to tell if they were as bad as mine because of the paint on them.
We came to the conclusion the the rough surface is from the laser used to cut the bar out. Apparently Stihl is no longer grinding the top of the rails on the bar.
It should smooth up after I dress the bar a couple of times.

Ed

How often do you dress the bar? Those "pits" should be long gone before your first dressing.

 

[Ed*L]

How often do you dress the bar? Those "pits" should be long gone before your first dressing.

No set schedule on dressing the bar, when the saw is serviced I remove edge burrs & check for rail wear. Dress as required and check for squareness.
The "pitting" is deeper than I would ever wear a bar without dressing it.

Ed

 

[Oregon Engineer]

Update:.....
We came to the conclusion the the rough surface is from the laser used to cut the bar out. Apparently Stihl is no longer grinding the top of the rails on the bar.
It should smooth up after I dress the bar a couple of times.

Ed

I don't know the exact method Stihl uses to make the laminated bars. Most laminated bars are produced by stamping the side laminates and inner core. Stamping is a lot fast than laser. A stamped side laminate would have the type of surface finish shown in your pictures. I can't tell for certain because the picture is not close enough.

 

[hamradio]

On my 039 I had some issues. Bought a brand new 18" bar, but used an old chisel chain (STIHL) that was laying in my chainsaw toolbox. That chain ran so hot it burned up oil. I had it not very tight at all. Switched to a chipper, and the problem went away. I think I'll buy a new full chisel, since I like how fast they cut. Turned the bottom of my bar blue, actually.

 

[SawTroll]

Here's a pic of the bar, You can see the pitting is pretty constant the whole length. ...

What I think I see, is a bar that isn't used enough for the initial rough surface to even out.....

 

[SawTroll]

... I do keep the chain properly tensioned. You can't see the drivers when lightly pulled down. ....

That seems a bit tight to me.....