Hardware bought steel

[redvan22]

Hi,
I bought a piece of crs bar, 5/8" * 1 1/8" * 4' at my local Ace hardware store and this stuff is killing my fly cutter.

I cut off a length of 2 1/2" to square up and about two thirds of the way across, I begin to see sparks and immediately afterewards the finish goes from excellant to terrible.

I've resharpened the tool bit but as soon as I get near to the same point, it happens again, sparks and then dead cutting edge.

I'm reluctant to use an end mill for fear I'll destroy it.

Anyone have a clue what is happening here and/or a way to get past it?

Is this just terrible stock?

 

[Winegrower]

What I do is throw it in the fireplace/wood stove, the next morning it's like butter. It anneals by heating up then cooling very slowly.

 

[Shotgun]

Yes. It is terrible stock. That hard spot has been heated to the critical temperature and then cooled quickly.
I've got a 3" round that was in the chip pan when I bought my lathe. It had been flame-cut, but I needed an ER-32 collet chuck/block (yes. It is both a block and an a chuck). It left a beautiful finish, but was tough to cut. About 30 thou max, except near the flame cut. More that 10 though would break off the carbide insert. You could tell the hard spot by looking at it (it had a distinctly different sheen), and the hair-like metal streaming off as I cut it would burn as it came off.

@Winegrower has good advice. Get it all red hot and bury it in ashes.

 

[graham-xrf]

Go with the advice from @Winegrower .
You may or may not have a woodburner, but you might contrive a coal fire , helped by a hair dryer. Get it red, and then build a wood fire on top, and walk away from it. Ash is excellent stuff to insulate it from losing the heat.

Even then, take care when machining. What you have just cut might have gained properties it did not have when you started.

 

[pontiac428]

At least take a few minutes and grill some steaks if you're going to be firing up the charcoal BBQ to anneal your steel.

CRS is a curse. As bar stock, it has nice dimensionality and finish, but inside it's full of stresses and hard spots. It can really move around when milling, the bars and blocks curl as they are stress-relieved by metal removal. And on the lathe, CRS is atrocious. I consider it an emergency use only material, or stick to simple operations (which covers a lot of uses). I pretty much keep CRS off the mill and lthe. It's great for general fab work using the drill press, band saw, grinders, welding, so on.

I wonder if annealing CRS would relax those dimensional aberrations as well as normalizing the temper. I've never tried it with CRS. It would be nice if it weren't such a turd to machine. Anybody know?

That leads me to another question, is all 1018 a pain to machine, or is it just CRS because of the way it's formed?

 

[Shotgun]

Any time you take the metal above the critical temperature and cool it slowly, you will relieve stress as well as anneal it. Of course, you also risk the dimensionality and finish.

 

[K30]

That leads me to another question, is all 1018 a pain to machine, or is it just CRS because of the way it's formed?

And/or, was it always that way? Did it machine better when it was still made in a quality steel mill? 50 years ago, would the stuff stay straight?

 

[MrWhoopee]

Did it machine better when it was still made in a quality steel mill? 50 years ago, would the stuff stay straight?

No, at least not 45 years ago. The cold rolling process creates stresses which are relieved as the material is machined. The hard spots are another matter, 1018 SHOULD not contain enough carbon to produce a hard spot regardless of how quickly it is quenched. I've never encountered a hard spot in CRS, but then I've never bought it anywhere except from an actual steel distributor.

Re the OP, torch annealing (heat to cherry red) the hard spot and air cool SHOULD eliminate the problem.

 

[matthewsx]

Yes, anneal.

or

Buy the material you want.

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John

 

[G-ManBart]

For what you're doing a true annealing process is probably more than what you need, i.e. heat it all the way to critical temperature, and then bury it in ashes, or anything else for a slow cooling.

If you simply get it hot enough to show some color (red to orange) for a minute or so and air cool it will temper the metal enough you shouldn't have any issues machining it.

This works on truly hardened steel as well...have something like a knife blade you want to drill a hole in...heat that exact spot with an oxy/acetylene torch till it's orange, let it cool and you can drill right through it easily. In that case you'll want to keep the heat from traveling to parts you want to stay hard, so wet rags wrapped around the other areas, or having the rest dunked in water while you heat the spot will all work.