Question on 1018 and stress relieving

Guys

I'm about to start a kind of epic job.
Just over 700 complete assemblies of 8 components / each.
6 of the components are 1018, the other 2 is A2 at HRC 60+.

The A2 parts are given and of no concern.
My issue is with some of the 1018 details.
They are made from a rectangle bar of 2 x 3, are approx 6" long, and when done they are pretty much like swiss cheese.
Large(r) holes, slots, thin walls ... 70+% of the material is machined away.

None of the tolerances are stupid tight on the print, but I do foresee issues with proper fit if something moves or twists during machining.
From my experience, I've seen plane-jane 1018 do unexpected things at some of the times, and be completely stable at others.

So my question: Would it be a worthwile attempt to saw cut the blanks from the bar and send them out for annealing, normalizing, stress relieving or ( add the proper term here )?
Cost or added time is of no concern here.
Trouble free machining IS !!!

Thank You

SeymourDumore said:

Guys

I'm about to start a kind of epic job.
Just over 700 complete assemblies of 8 components / each.
6 of the components are 1018, the other 2 is A2 at HRC 60+.

The A2 parts are given and of no concern.
My issue is with some of the 1018 details.
They are made from a rectangle bar of 2 x 3, are approx 6" long, and when done they are pretty much like swiss cheese.
Large(r) holes, slots, thin walls ... 70+% of the material is machined away.

None of the tolerances are stupid tight on the print, but I do foresee issues with proper fit if something moves or twists during machining.
From my experience, I've seen plane-jane 1018 do unexpected things at some of the times, and be completely stable at others.

So my question: Would it be a worthwile attempt to saw cut the blanks from the bar and send them out for annealing, normalizing, stress relieving or ( add the proper term here )?
Cost or added time is of no concern here.
Trouble free machining IS !!!

Thank You

Click to expand...

it would help if you cut the scale off 1st and pop a hole or 2 in it.. then normiize harden and temper.
if you send to before you cut it will spring like heck when you take the scale off.

I'm certainly no authority on the subject but if concerned about warping the part then my experience would suggest roughing the part and leaving stock on more critical features. Have it stress relieved or normalize (different process/results) followed by final machining. There's definitely a possibility of the parts coming back from HT very changed regarding flatness, especially if you're removing 70% of the material so the potato chip effect may call for a face cut on top/bottom if that matters. No mention made on fitment/feature critical tolerances so I can't offer a valid opinion. "Trouble free machining" can mean a lot of different things and a wide range of tolerance values. If time/money is less of a concern I'd give the HT a call. Stress relieving the material can also relieve some of the stress on you. You already have enough to worry about. Good luck.

If this is cold-finished 1018, I'd not worry too much about through holes. Removing material from one face, however, can cause the bar to curl up like a banana. Not talking tenths of thousandths, but tenths of inches removing about half the thickness of some 1/4x1 bar for about 8" length. Stress relieving should help considerably with that behavior.

Rough, stress relieve, finish machine.

Better safe than sorry.

You need to bear in mind that the stresses induced in cold-finished material are mechanical and not
necessarily related to any heat treat process. I would be inclined to experiment with a couple samples
to see if annealing removes all of the internal stresses...

EmanuelGoldstein said:

Rough, stress relieve, finish machine.

Click to expand...

Can't do! ( And that applies to milling, drilling or otherwise removing "some" material prior )
Material in -> ??? - > Machine -> Finished part out.


'Bout the better safe then sorry part .... We'll try to make it work.


At some point in the past I was told that a stress relieved block cut from A36 plate was better to machine complete than using a 1018 rectangular bar for the same.

Machined both.
The A36 flame-cut plate + "whatever treatment" process was always reliable, but having to square shit up first was a bitch.
1018 Flat bar was always easier ( quicker ) to process from the get-go, but I often had to deal with some of "this and that" for the final ops.

To date I've never had this many pcs to process from the same material, so I'm asking what would be better....

I might suggest HRS instead of CRS, bar stock,not flame cut,might.....
good luck,sounds exciting.
Gw

SeymourDumore said:

Material in -> ??? - > Machine -> Finished part out.

Click to expand...

Kerpoopie

All I can think then is, second vote for GW's idea, use hot rolled instead of cold finished. One less batch of mechanical stress in the raw material.

Won't annealing the 1018 reduce the tensile strength of the part? I had a part I had to machine out of 1018 that was 1/2" thick stock and about 25" long. Ended up doing three sets of passes to get to the right thickness (around 10mm iirc). Each time the part was flipped it would warp a bit less.

SeymourDumore said:

Guys

I'm about to start a kind of epic job.
Just over 700 complete assemblies of 8 components / each.
6 of the components are 1018, the other 2 is A2 at HRC 60+.

The A2 parts are given and of no concern.
My issue is with some of the 1018 details.
They are made from a rectangle bar of 2 x 3, are approx 6" long, and when done they are pretty much like swiss cheese.
Large(r) holes, slots, thin walls ... 70+% of the material is machined away.

None of the tolerances are stupid tight on the print, but I do foresee issues with proper fit if something moves or twists during machining.
From my experience, I've seen plane-jane 1018 do unexpected things at some of the times, and be completely stable at others.

So my question: Would it be a worthwile attempt to saw cut the blanks from the bar and send them out for annealing, normalizing, stress relieving or ( add the proper term here )?
Cost or added time is of no concern here.
Trouble free machining IS !!!

Thank You

Click to expand...

.
1) depends on tolerances of part
.
2) stress relieving in bulk doesnt cost that much. that is when furnace is filled to max with parts as opposed to only one part the cost per part to stress relieve is low. Say its $100. to heat furnace, energy and labor. obviously if there is over 100 parts in the furnace compared to one part the cost per part is different.
.
2)consistency of parts. tracking total time to make a part including rework, remaking often its cheaper and faster to do many things that at first seem more expensive or slower
.
3) parts warping yes many will warp or curl immediately after unchucking but many parts need time and will continue to warp or curl after some time has gone by. thus rechucking and taking finish cuts part can easily still warp or curl some more later
.
4) A36 plate can be full of stress, obviously anybody using a jig saw, saber saw or sawsall cutting shape out of a sheet and have saw kerf close up at the last part of cut, seen it thousands of times can tell you that. A36 can also be full of larger hard spots of slag compared to rolled stock. also A36 sheet when sheared if piece sheared is small width the shearing induces a large amount of stress into the part often worse than if piece was just cold rolled steel
.
4) hot rolled is not necessarily stress relieved. if rolling continues and steel bar was below red heat its same as cold rolling. cold rolled has mill scale pickled off with chemicals. basically hot roll can be under same cold rolled stress it just didnt get pickeled or chemical treatment to remove mill scale. sometimes cold rolled after chemical treatment is a smoother shape and could be more accurate to nominal size and shape. doesnt mean that after machining it will not warp or curl. some cold rolled parts might only get cut to length and a few holes drilled thus warpage often not a issue

Yes, I would absolutely send these out for stress relief. Makes a huge difference.

Heat treaters charge by the pound. Around here, $0.30-$0.40 per pound with a $150 lot minimum. 1018's pricey these days so stress relief is a minor cost component, but should still be factored in.

In a pinch I've done it in house. Heated to 1500F, just under austenitizing temp, then furnace cooled overnight.

dksoba said:

Won't annealing the 1018 reduce the tensile strength of the part? I had a part I had to machine out of 1018 that was 1/2" thick stock and about 25" long. Ended up doing three sets of passes to get to the right thickness (around 10mm iirc). Each time the part was flipped it would warp a bit less.

Click to expand...

1018 specifications are in the annealed state. The low carbon indicated by the "18" makes it so that it'll only harden through a case hardening method, e.g. carburization.

Personal health and sane state of mind are the most important things in my opinion, and you should definitely prioritize them. You could get overwhelmed very easily, so if I were you, I would take things slow, one at a time. Stress can be a tricky condition, you might thing that it will go away with time, but actually if it is not resolved at a decent point in time it can result in major health issues later on. In the past, I used this great online platform Please Wait... | Cloudflare that helps people to tackle the issue of stress properly, providing various insights into medical facts. I followed their advice consistently and had amazing results with my stress issues.

MrIkari said:

Personal health and sane state of mind are the most important things in my opinion, and you should definitely prioritize them. You could get overwhelmed very easily, so if I were you, I would take things slow, one at a time. Stress can be a tricky condition, you might thing that it will go away with time, but actually if it is not resolved at a decent point in time it can result in major health issues later on. In the past, I used this great online platform <REMOVED> that helps people to tackle the issue of stress properly, providing various insights into medical facts. I followed their advice consistently and had amazing results with my stress issues.

Click to expand...

Go jump in a heat treat furnace, for fucks sake. There'll be a lot less stress left in you after that.


I know replying to the bot isn't helpful.

Just ran a smaller quantity job than yours about a month ago out of 1018 ,went ahead and had all the material stress relieved (after sawing). One part was .375 x 60mm wide x 80mm long. Best I remember about 20 pcs , it was milled down to 3mm thick with a 20mm shoulder, no problems with it being flat after that much material removal. You will have some scale build up but that won't be anything like dealing with warpage. I would do it the same way again.

If you want little to no movement hot rolled is the way to go. The pain (expense) is finishing the outsides all over… A36 will work the same as HR bar stock but you have to know the grain direction. If it’s a burnout or plate sawed it should have an arrow painted on it showing the rolling direction.

Good luck,
Matt

yes, sounds like a very good idea to send blanks out, probably better to get them annealed, not just stress relived.
just as important though is to get material from a good trusted source.
order cold rolled in the minimum temper available (1/8 hard perhaps?). I don't know if they usually produce that thickness in other tempers, but what that means (for those who don't already know) is how many times it is sent through the rolls after annealing and pickling. talk to your supplier, and explain what you need, it is possible they can supply bar that is specifically intended to be machined and stay stable. probably just gets a "truing pass" through the rolls without any significant reduction in section.

Interesting that a retard resurrected this thread ...
At least I can do a proper follow up:

We've done the same job now 3 times. All out of cold rolled flat stock as that was reliably seating in the jaws with minimal grip depth.
Flat bar in -> Saw cut -> Stress relieve - > Machine - > Never an issue!!!

Greg White said:

I might suggest HRS instead of CRS, bar stock,not flame cut,might...

Click to expand...

If you're going to consider hot rolled take a serious look at 44W instead of A36. The former machines
much nicer than the latter. No where near as gummy and much easier to break a chip. Obviously won't
work in all situations but it's worth a try. I occasionally have to machine steel adapter rings from flame cut
blanks and I discovered how much nicer it is to work with 44W...

It would be cheaper in long run to swap material for HRS or 4140 than to deal with warping issues.