Steel that is weldable and machinable?

[macona]

I am making some parts for my little hit and miss and bought 1018 to make them out of. What a mistake! Stuff is darned near impossible to get a good finish without tearing.

So I am thinking about using 1144 stress proof. A couple of the parts need to be welded though. Is there any grades of steel that I can get a nice finish and weld?

Almost ready to just use some stainless!

[Forrest Addy]

1144 is a resulfurized medium carbon steel. Look at the analysis:

C 0.40-0.48
Mn 1.35-1.65
P 0.04 (max)
S 0.24-0.33 (normally held to less than 0.05%)

It's not reccommended to weld sulfurized or leaded steel because of the effect the sulfur and/or the lead has on the weld deposit. A weld procedure normally used for structural steel may crack catastrophically in medium carbon steels. Medium carbon steels are weldable with the right filler metal and the proper pre and post heat to control heat affected zone hardening and carbon segregation.

Pardon me while I go into rant mode: People say they weld resulfurized and leaded steel and "get good welds". If they were to weld a few fillet weld samples and break them to look at the fusion line and the heat affected zone under magnification, they would not be so confident of their prowess. I strongly suggest newb welders seek good advice before welding anything where strength or reliability counts. By good advice I do not mean blithe assurances from yokels and shade tree metalworkers whose main qualifications are ignorance and dependance on luck. Anyone who welds over paint, rust, and dirt demonstrates by doing so he's not qualified to bulild a crab trap.

I mean good advice taken from books on weld procedures, teachers of welding, weld engineers, and experienced welders who have had benefit of formal training as in an apprenticeship or any combination of the above. Tons of free information is available at your local welding supply house. They sell books of basic welding procedures for a pittance where they aren't free.

Broadly speaking, most steels are weldable provided precautions are taken for alloy and carbon content (preheats etc.) There's are cookbook solutions and welding procedures for most any combination of materials. There's a few ferrous alloys that can be welded to almost anything and austinetic stainlesses are among them.

Home brew structure welding may not be as stringent as nuclear pressure vessel welding but suitable care using the right stuff is still important if you are to make strong ductile welds. Weld clean over bright metal using the right filler metal, joint prep, machine settings, and procedures.

Rant off.

Many modeling metals joining requirements may be satsfied via silver brazing. It's also possible to get good results with silicon bronze filler metal which comes in a fluxed arc rod and a bare TIG rod.

Mild steel can be quite variable in its machining properties. It's not uncommon to find that finishes are almost impossible to secure without exerting heroic efforts. You might get better results with free machining alloys provided you don't try to weld them. They will silver braze and join with brass brazing or silicon bronze arc welding (actually brazing). A better machining steel for welding purposes would be 1140, 4130, or 8620. All have acceptable machining properties and can be welded so long as their carbon and/or chrome content is respected. Neither contain sulfur or lead although there are versions of these alloys that do.

99% of the time home welding is not rocket science but if you can follow cookbook directions from a book you can weld to any level your developing skill and shop equipment will support.

[Spin Doctor]

Forrst, I concur. This whole welding 1144 drives me nuts. With .44% Carbon it can be direct hardened. Would anybody weld 4140 and not expect problems. As to finish problems with CRS. On the lathe the tools need enough tool nose radius and positive top, side, back and nose clearance angles. If you are using chip breakers make sure that they do NOT direct the chip so that it drags back on the surface of the work behind the tool. This is a situation where a nice tight curling or spiraled chip is desirable. In the mill sharp cutters used at moderate speed (100 t0 125 SFM is plenty). In the shaper same as the lathe but even more top rake. For coolant, oils and soluable oil based coolants work best IMO. The more expensive Tap Magic, Rapid Tap etc save for tapped and reamed holes.

Just my .02$

[J Tiers]

I am not so sure the issue with 1018 is with the chip curling back on the surface. By the time the chip has done so, it will be cold enough that its worst effect would be to score the surface, and that is NEVER what I see.

I believe that the 1018 gets a built-up edge on the tool, which can happen with most any tool geometry. I think it is a classic case of the built-up edge having two effects....

1) It isn't as clean a cut because it isn't a sharp edge, more-or-less "wadding up" the metal rather than cutting it.

2) part of the build-up welds itself onto the work surface and is torn off to remain on the surface.

That seems to be the classic case..... a roughish surface, with "tags" stuck to it all over.

Oil helps, presumably "poisoning" the weld and reducing the tendency to stick on as a built-up edge. But it rarely cures.

I have found that a combo of oil, slowing down AND a high rake tool may help.

[Lew Hartswick]

I have found that a combo of oil, slowing down AND a high rake tool may help.

What angle rake would you consider "high"? I would like to try this
on a few samples at school to see if we can improve the results on
some projects. Most of the lathe bits are ground with a nearly 0 deg
rake. (It makes regrinding a lot easier which has to be done often)
Thanks.
...lew...

[Spin Doctor]

What angle rake would you consider "high"? I would like to try this
on a few samples at school to see if we can improve the results on
some projects. Most of the lathe bits are ground with a nearly 0 deg
rake. (It makes regrinding a lot easier which has to be done often)
Thanks.
...lew...

Here is one instane were a diamond type tool holder could be used to experiment. On the shaper I used to use a type of tool made for production Cone-a-Matics. The blanks were 1/2x1 Vasco Supreme. The tool had about a 1/8th tool nose radius. Maybe 5D side rake. The nose and back side clearance was closer to 15 by the time you got around to the back side of the tool. The top rake was maybe 30D angled towards the back side and rear of the tool. I'll have to see if I have one still in the box as I brought most of my cutters hoem when I retired. In the shaper this tool regularily took .250 in CRS, .125 in TS and .125 in Aluminum Bronzes (Ampco14, 18 & 24) with .010 feed as long as you didn't push the ram too fast. Nice smooth finish too. The tool originally was used to machine 4140

[J Tiers]

Grinding the tool with a very small nose radius, and a high SIDE rake, 30 deg or so, has worked.

The usual lathe tool that is ground as if you were going to cut on the tip, radially, is not good for this.

I grind them so they cut on the SIDE, with a near radial edge, and a relief behind the front left corner. I also try to do one cut to final dimension when possible. This does end up with some large DOCs, but it usually works.

[wierdscience]

The main problem to be adoived in welding is contraction stress.After a weld is laid it must be able cool and contract.If it cannot it will eiter crack internally or it will pull free from the base metal or it will distort the section being welded.

To avoid the effects of contaction stress,never fit up parts tight.The surest way to fail a weld is to but the parts being joined together tight.Typically 1/3 the material thickness or one filler rod diameter is sufficiant to prevent contraction stress.

Now a word about what can and cannot be welded.

Nearly all types of steel can be welded including 1144 and 12l14.It's not that difficult.Low hydrogen weld rod is the prefered choice,you should avoid 60xx series rods,they are ment for gouging in and welding trough rust,paint,dirt etc.

About the strength of the finished part.Anything critcal should be x-rayed or magnafluxed,but your not building submarines,reactors or boilers so this doesn't really apply to you.

Look at the choice of materials in the first place,you wouldn't use 1144 or 12l14 on anything that needed to take a high stress welded or not so the question of high stress welds here is mute.A bead of low-hy weld will be stronger than the base material and if proper fitting and pre-heating is used will be as will work for anything the base material can handle.

Here is a good source for basic welding information of the general types-

http://www.key-to-steel.com/FR/Articles/Art68.htm

About machinbility,the material you intend to weld and the weld itself may both be machineable,but don't count on either machining well.Even if they do there usually will be a color and or finish distortion between the two metals.

If cold rolled 1018 is giving you problems,try hot rolled.It may still leave a "muddy" finish,but that can be dealt with by changing tool geometry and adding some lube.
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Rant mode on,Forrest and Spin are right on one point and wrong on others.Procedure needs to be followed,but common sense and logic must also play a role.
Would I weld 1144 or 12l14?Yes,I have and yes I do.Will I weld it if it is a high stress part?No I won't....but then again niether 1144 or 12l14 should be used for a part subjected to high stress welded or not so it's a mute point.

The page I linked to above lists welding procedures for low,medium and high carbon steels and the filler metals to weld them with.

Do I weld 4xxx series steels?Yes,frequently,they are among the most commonly welded steels in the business.Fifth wheel pins on semi truck trailers are all forged 4140-4130 and are all welded.4xxx steels are not out of reach of the experienced amatuer if the stresses and procedures are all taken into account.
The wrong choice of material,poor design or improper procedure will cause a fair degree of damage and death even if the part requires no welding whatsoever.
Over complicating a subject when that degree of complexity isn't warrantied serves no good.The OP isn't building a neuclear sub,or a reactor vessel or even a trailer hitch,all he wants to do is weld up some assemblies and machine them afterwards-Rant mode off.

[dalee100]

Hi,

I would "temper" Forrest's rant a bit. One can weld 1144 to "mild" steel with acceptable results. Not text book perfect, but acceptable. I do it at work on a regular basis. Though I must qualify that statement by saying these are NOT unsupported butt-welds in high load/stress situations. Still, even then certain amount of failure is to be expected.

Forrest is absolutely right about how the weld breakage will look. There will be an extremely clear demarcation lines between the mild steel, weld, and 1144. Magnification isn't needed to see the crystallization of the 1144. More interesting is the crystalline appearance of the weld. Those that fail out of the box, so to speak, show a much poorer "mixing" of the three materials in the weld area. Those that hold up seem to have a much better and "smoother mix". How to tell which welds are better? Let the customer sort it out . Out of the several hundred times I build these kinds of tooling for customers every year, I expect to get 1 to 3 warranty failures a year, (1 year warranty).

So it can be done. One can even make a living doing it and have satisfied customers. I don't like doing it, but it's not my call.

Spin Doctor, if you think welding on 4140 is naughty, you should see what I sometimes have to do to S5 and S7 steels !

Macona, finish problems can stem from a number of variables. Everything from poor process selection, to improper tool selection and geometry, bad material, i.e. Honda bumper syndrome, to poor setup of stock, to poor machine condition. Any one of these or combination will cause less than desirable results.

Assuming your machine is tight and fit, look to your setup first. Is it ridged enough? If you are working out of a lathe chuck is your over-hang less than 2X's the diameter of your finished part? If not shorten it up as much as possible or use out-board support. In a mill, don't over hang the vise too much.

Next consider tool selection and geometry. A TPG-323 insert used in a 7x14 lathe or Mini-mill is a less than ideal selection. My opinion is that carbide inserts are more a hindrance than help in bench-top type machines. Generally there isn't enough mass, power, and speed available to give good results. So maybe HSS tools would be best for you if you are using smaller machines. A general rule is, the lighter weight, and lower the power, the sharper your tool needs to be. So be careful of just how much you radius your tool.

Coolant or cutting fluids can go a long ways to improve finishes too. Just remember, if using carbides, flood heavily only, no misting or dribbling. Otherwise thermal shock can break your inserts and heart.

Sometimes you can get bad material. Not much you can do about it. Other than live with it, or toss it out.

If you need a high finish on your parts, you should consider secondary operations to achieve proper finish. That could be anything from simple sandpaper/filing, to surface or cylindrical grinding, to burnishing. These are processes are generally used when good finish is a concern.

dalee

[Dick Plasencia]

I suggest that if you are not getting a nice finish on 1080 you look at the machining and not at the steel. I get mirror finishes as a matter of fact. It welds like a dream.