rcm - productivity SMAW 6013 vs 7018

• posted

Hi all

Back again - in via a new NNTP server. Been gone more than a month.

This came to me about 3rd Feb...

With more welding experience repairing the hull of a seagoing vessel, the meaning of the wise words of a late mentor who used to contribute a lot on here came to me.

I've appended my calculations.

To get a 6mm fillet, you could have

• a 3.2mm-dia (1/8th-inch) 7018 rod at about 125A
• a 5.0mm-dia 6013 (~3/16-inch) at about 200A

If productivity is proportional to Amps, productivity of 6013 is 160% of the productivity of 7018.

Yes 7018 is massively tough compared to 6013. But sometimes you can tear-out the plate-surface with a good 6013 fillet, so there is {sometimes} no call for vastly more toughness and ductility.

This dawned on me when I was wondering why people were bothering weaving 3.2mm 6013 building up a big bead. For eg. lap joints overplating a steel hull, that 200A is not a problem because the run-rate is fast - twice that of 7018 - and the polarity is Direct Current Electrode Negative (DCEN) - smooth and consistent but not very penetrative, so at 200A you'd be absolutely fine "striping" a 6013 fillet.

I've just "seen it". If I've got this right... Have I got this right?

Regards, Rich Smith

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A_rod=pi.d^2/4 A_fillet=z^2/2

6013

----

run-out-length = rod length A_fillet=A_rod

z=sqrt(pi.d^2/2)

(defun z-6013 (roddia) (sqrt (/ (* pi (expt roddia 2)) 2e0)))

(sqrt (* (my-circle-area-dia 3.2) 2)) ;; 4.010605239409601 (z-6013 3.2) ;; 4.010605239409601

7018

----

run-out-length = half of rod length A_fillet=2.A_rod z=sqrt(pi.d^2/4)

(defun z-7018 (roddia) (sqrt (* pi (expt roddia 2))))

(z-7018 3.2) ;; 5.671852322897651 (sqrt (* (my-circle-area-dia 3.2) 4)) ;; 5.671852322897651

================================================================

(z-7018 3.2) ;; 5.671852322897651 ;; that would be at about 125A (z-6013 4.0) ;; 5.0132565492620005 ;; that would be at about 160A? (z-6013 5.0) ;; 6.266570686577501 ;; that would be at about 200A?

For given fillet size, productivity would be much increased with 6013 vs 7018. Compensating for all factors and using 5mm 6013 for 3.2mm 7018, (/f 200 125) ;; 1.6 more than half as fast again.

Remember 5mm 6013 for 6mm fillet...

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(z-6013 6) ;; 7.519884823893001 (z-7018 4) ;; 7.0898154036220635

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Also think with 6013, are on DCEN and running fast, so can weld material of thickness about the rod dia? Fits with all I have seen. eg. my "short arc training T-fillet" (Newham College, etc.)

• posted

Yes 7018 is massively tough compared to 6013. But sometimes you can tear-out the plate-surface with a good 6013 fillet, so there is {sometimes} no call for vastly more toughness and ductility.

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This suggests that 6013 is acceptable in the UK for many critical applications:

"Applications include: plate for ship hull construction, site and workshop welding of pipes and pipeline, construction of pedestrian walkways and bridges, vehicle and boiler construction as well as a great variety of general construction and workshop applications."

Of course that is ad copy, not a legal specification.

The test I learned was to bend the test coupon weld in a hydraulic press, as it is commonly available shop equipment while other testers such as yours aren't. Is that a standard acceptance test?

• posted

Hi Jim, everyone

I think roundly ignore the publicity blurb.

"Nikko Steel" is an Indonesian manufacturer of welding rods.

I've been largely excluded from engineering in the UK and worked as a welder. So I cannot comment "policy, in general".

I can say from my own observations and experience...

6013 is easy to break in the weld. You have the original steels in the original condition and the weld is history - gone. 7018 even a small weld will "force" general bending of the sections joined. "Distributing the attack" of a grievous event. Giving a very resilient structure. It would be cheaper to use a "correctly sized" 7018 fillet weld than an "oversized" "would survive" 6013 fillet weld.

Then there's the reliability of the well-penetrating 7018 weld, its easy positional welding, etc, etc, etc, etc, etc...

I was commenting for low-stressed welds on economical steels meeting spec. by not necessarily a big margin.

If you look at others in the ad., there's 7018 "Nikko Steel RD718". Which I have used. I'll be wary given my limited range of experience, but - they are good. "Weird" compared to "modern" 7018's, most welders say.

A retired weld-engineer friend reckons a very 1970's-style rod - good when burning for eg. properties and slag containing / shaping weld bead - but not otherwise user-friendly.

I got 150A vertical-up with an RD718. That would have been with a 4mm rod.

I have never seen tests being done here. People here get angry and start shouting if they see you testing anything - settings, techniques, "tests" as you mention - even if you are going to a high-value weld with a limited access-window - eg. due to the tides of the sea and when you can get there.

Bend around a former, typically using a hydraulic press, is known here for butt-welds, yes - but you wouldn't find the test "everywhere". A good welding college would have a hand-pumped one.

In Canada I saw colleges had a compressed-air pump driven hydraulic bending rig, so students could freely walk-up with their prepared test-strips (transverse across their butt weld), put it in the rig, press foot on the valve and have their bend done in seconds.

Regards, Rich Smith

• posted

There are many in the UK who have their own home shop. I have read some complaints about availability for welding gasses, but it seems to be a surmountable obstacle. Would it be worth it to you to setup to do your own tests in your own home shop or perhaps a small local job shop where you can befriend the owner? Perhaps you could coordinate with a welding school. They could do real world tests and education the next generation of commerical and industrial welders of issues that may concern you. For the most part it would be for your own comfort in the results, but if something comes to your awareness that you feel is a safety issue you can't ignore in good conscience maybe you can pass it to safety regulators anonymously.

I realize a home shop may not be able to run the same machines and material as an industrial shop, but basic tests could be done. I do also realize that sometimes issues or results do not scale, but it could provide a basic result to help you determine if application size testing is warranted.

6013 vs 7018. Is it? If so have you dismissed the possibley of the choice being based on the higher potential for hydrogen embrittlement of 7018 in a wet environment?
• posted

Hi Bob, everyone

I have a space now for a workshop and test facility. I do want to be able to do tests.

Hydrogen arguments are spurious for any reasonable-quality "mild" / weldable structural steel at low thicknesses. At 12mm / 1/2" and less

- for all "normal" circumstances "forget it". You can't work up the frozen-in stresses and the hydrogen leaves too quickly.

I have been amused that "Lo-Hi's" are anything but unless handled in a very specific way.

7018's kept in a shed or a lot of work environments have as much hydrogen as 6013's, for sure. I have been amused seeing water dripping out of rod-ovens as huge amounts of water are driven-off - and electrodes are used in the saturated state believing they are "Low Hydrogen". 7018's run cleaner when dry - sole reason for most circumstances that I rod-oven them. Don't rod-oven anything but "Basic"/CaCO3-based rods - the xx18's and xx28's - as those rods - mainly the 6013's, the xx10's and xx11's rely on the moisture for shielding.

I have become interested in Aluminium MIG / Aluminum GMAW, which I meet in marine work as the 5000-series Al-Mg alloys.

"Ali MIG/GMAW welding with quality control" That would involve a lot of testing.

Rich S

• posted

Okay. I had heard that 7018 is hydroscopic and will draw moisture from the air. For example I keep my 7018 in short pieces of PVC pipe with a cap glued on one end with a screw on cap at the other. If I feel I need to use rod instead of MIG I put a few pieces at a time in my toaster oven for drying. That may be overkill since I live in the desert where most of the year we see 5-15% humidity, and even during our "monsoon" season we rarely see above 30-40%. Being a novice (at best) I tend towards caution in things I can't see. Generally I do not weld steel that requires more the capability of my Miller MIG welder (since I learned the problems I had weren't all me.) As a result the last time I bought 7018 was a number of years ago. I have a couple pounds in tubes, but if I had to weld something I considered import I would probably buy fresh sealed cans.

I am aware that some rod may be easier for out of position welding, but I tend to use flux core for that if another process is not mandatory. Since I weld almost exclusively for myself I try to make sure it never is.

Would it be fair to say that issues of hydrogen embrittlement with 7018 rod that is not properly stored and cared for are largely overblown?

I do keep a toaster oven in the shop, but it gets used more for powder coating small parts and preheating resin casting molds than anything.

Sorry about the GMAW aluminum. Can't help even a little bit. I have already shared 100% of everything I know about that and probably used twice as many words as is necessary. I have done it. The boat didn't sink. The end. LOL.

I like that you say 5000s series. Generally sheet and plate I've found readily available is 5052 and I have been told structural is often 5086, but I've never found a commercial source for 5086 (other than sheet or plate) that will sell to me. In fact often for structural non-sheet members I am forced to use 6061 which is not as corrosion resistant as

5000 series. Alternatively I brake 5052 into structural shapes. In my current long term project I am turning 5052 shapes into extra strong structural components by filling with "CarbonBond Pourable Ceramic Transom Compound." I'm repairing an old boat that belong to an old friend, and separately building a bigger boat for fun days on the river.
• posted

No, not related to previous threads. Well there is some small overlap, but nothing intentional.

This comes from in October working on the renovation of a "dutch" barge. I did some welds on the hull - the overplating. That, independently of anything before, made me think. Lot of chat previously mainly about "quality". This was a pure insight into "productivity" - what electrode would enable you to do an acceptable weld cheapest? Some North American advice said more than a decade ago (?) suddenly made sense - "snapped into focus".

• posted

This belongs in the "AWS Farm Code" (it's a joke Code)... If the flux hasn't busted off the rod due to rusting it's still usable for "Farm Code" welds. If you are that uncertain about 7018, how much moisture it has is fairly irrelevant. Not holding the correct short arc length all the time evaluates as a much more serious error. Do dry your 7018 rods "like mad" if you are doing a "forbidden" weld like a hardenable steel for implements to a mild-steel shank, or the like. eg. put them on a clean baking tray in the kitchen oven at minimum the temperature you'd use for cookies. This is all "Farm Code" territory. Do none of these things for any engineering job.

• posted

I have a space now for a workshop and test facility. I do want to be able to do tests.

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Your fillet weld test fixture could be converted to a tensile strength tester with a slight modification. Replace the fillet sample with two bars hinged together at the bottom where the press bears on them and linked to the sample at the top. The breaking stress would be similar to the upper fillet alone.

The sample could be a butt or lap weld between rectangular coupons. They would be drilled to pin them to the fixture and milled away along the welds to leave a known cross section with rounded lead-ins.

You can make almost anything with a thread-cutting lathe and a vertical knee mill, which doubles as a drill press. I don't have enough experience with mill-drills to comment on their limitations vs a knee mill.

This is my mill, on the very bottom end of what a commercial shop could use, occasionally, but good enough for all I've asked of it.

have similar capacity and better R8 spindle tapers.

My 5" center height lathe is also small for a commercial shop, but adequate for my experimental, tool and repair parts making.

They would have equipped a very nice shop for an inventor or model maker in the 1960's when they were new and unworn. I don't believe they were ever intended as money-makers in a production setting, which means their price and remaining condition were reasonable.

I wouldn't trade my '65 South Bend for a '65 Mustang.

• posted

The Clausing mill is a machine you'd have on a ship, not in a machine-shop? It can do everything and is very adaptable. But you have to work gently. Making it opposite to the "do just one thing well, on 12hr shifts as hard as the technological limit".

That fellow - at lathes.co.uk - known him for decades. He's only a few miles from where I am now.

My skills which have shone in some environments (eg. sort-out the welding on a US\$2.7Billion project which had stalled) did emerge out of mental illness in the family. At price that that as I became successful and off in a career in the wide world, that mental illness slammed into me. That disconnected world as a kid had me thoughtful. Hence the skills which enable me to walk into a workplace, identify what's going on and what's gone wrong, and fix it.

Reason I get on with folk, as a "thoughtful" guy - sometimes that's the only major employer in the town and the future doesn't look great if that company were to collapse - so we get-along, build trust, team-up and everyone is happy.

Getting a lathe when a kid/youth looks to have been my blossoming "internal programming" seeking an engineering route. I didn't succeed with anything useful - but mustn't be too hard on myself - I felt the draw but didn't know how to do it. These days I have a list of things I'd really like to do.

Using machine tools was central to my Doctorate where I measured what no-one had come close to before (How quickly weld hydrogen moves through welds? Where is it when the weld is completed and where does it go in time?). By "sliding" scientific ideas of what would be useful to measure across what is possible to do, I saw an "alignment" where what you could do in a machine-shop enabled what would be scientifically very useful. It was "only" basic machine-shop stuff, but time - I needed to get the machining done very quickly as early results were vastly more valuable that later results - meant needing to see my way through a lot of detail, scientific and technical / machine-shop. I was taking 6mm cuts with a carbide-insert shell-cutter about 80mm diameter running at about 760rpm, which produced steel chips at about the rate of a chain-saw going through a log. I had to have a brush beside me and not move my feet, brush around my feet then walk along pushing the brush creating a pathway through the blue-hot chips all over the workshop floor.

With my next birthday being my 60th, I can see the youth trying to find what wasn't there in his environment. I also sent off "mail order" for a welding machine - a "buzz-box". Again - I can see why I floundered and had a beating-myself-up shortage of overall success then - but it was the start of a path.

That test of fillet weld strength - I had just half an hour of free time given some hold-up at work, and by the end of that half hour was looking at a successfully completed trial which showed a well-performing method.

I hadn't worked out how you'd convert the force on the hydraulic piston to the force and therefore stress in the test weld at that juncture, by the way. At home in the evening(s) I had to play around with ideas and found the answer in Newton's Laws.

Using the method for tensile tests... Yes.

A brilliant one for tensile tests including fatigue tensile came to me. When I was cycling up a hill and getting flecks in my vision from the exertion...

Corollary of

"the hydraulic cylinder needed for a tensile test is always bigger than the sample" (prevents you having an inserted cylinder inside a self-contained "self-structural" sample)

is

the sample will always it inside the hydraulic cylinder doing the test

"inner" hydraulic test A 200Tonne test would be about 400mm diameter - very doable.

That is something I would do when I get a workshop organised. Obviously I'd take it to a wide-open field to try it out first time - find-out what really happens.

BTW, That "beam-configuration fillet-weld tensile test" sound like a large-calibre rifle going-off when the sample breaks - inside a building... It's hilarious that I kept my job when sneaking-through those tests (employer was having "challenges" with a major customer, and knew that if a showdown came, "quid pro quo", I would help and even represent them).

• posted

"Beam-Configuration Fillet-Weld Tensile Test" for butt sample. The BCFWTT converts the force from a "simple" common "push" extending cylinder into a tensile force on the test weld. Which isn't easy to do. So yes there is a big incentive to attach - if necessary weld - your tensile sample to the top (tension) side of the test-beam.

• posted

The Clausing mill is a machine you'd have on a ship, not in a machine-shop? It can do everything and is very adaptable. But you have to work gently. Making it opposite to the "do just one thing well, on 12hr shifts as hard as the technological limit".

That fellow - at lathes.co.uk - known him for decades. He's only a few miles from where I am now.

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Yes, the old Clausing is limited, I gave it as an example of how small a machine you could do serious work with if you had to. For example I milled and drilled the center splice for the 16' gantry track on it, though I had to match-drill the holes in the assembled beam outdoors with a Portalign drilling fixture. The advantage of that type is that it can be taken apart and hand-carried to wherever you have space for it on a floor that can hold ~700 Lbs plus the operator, and the knee gives 0.001" precision in the vertical. Mine was on the top floor of an old mill building. I disassembled it enough to lift the parts into (and out of) my pickup truck.

There is a current production model similar to the Clausing with a standard R8 spindle taper.

Harbor Freight offers one for less:
In the 1990's I examined an Enco version with decently machined major parts but crappy small ones. I didn't test its accuracy or squareness. My impression was that if well made it would be a useful hobby or model shop machine for one-off parts designed within its size limitations.

Larger, heavier mills do more faster and a used one may be priced lower, but they tend to need a thick concrete floor with easy access to move them in.

Mill-drills are lighter, cheaper and nearly as capable. I've used only an RF-31 which might have been sufficient for structural steel fab but it wasn't accurate to better than 0.005", possibly good enough for static structures, marginal for power trains. I couldn't make a precision part for an IC handler on it and took the job home to the Clausing.

I've used a Smithy Granite combo machine, only when the company's CNC lathe and Bridgeport were tied up. My nearly 50 year old South Bend lathe is still better.

-jsw

• posted

Generally I've found the rare hard(ish) to not so hard just works better with preheat, peining, and post heat. Stainless wire also seems to work for this sort of thing (tool steel to cast iron or tool steel to railroad track). I actually have some nickle rod for that sort of thing, but since acquiring it at a closeout an application has not presented itself. Technically farm code might apply since I do have a hard ASR500 steel ripper tooth attached to a miid steel frame for my tractor, but I was one of those gouche Americans who just used bolts. Technically calling me a farmer might be a stretch, although I admit it was a greasy old farm mechanic who taught me how to weld with a cutting torch and a wire clothes hanger.

• posted

Technically calling me a farmer might be a stretch, although I admit it was a greasy old farm mechanic who taught me how to weld with a cutting torch and a wire clothes hanger.

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I proudly qualify as a hack too, since I first learned to weld in a farm repair shop, drive a 30+ year old pickup truck and own two (very small) tractors.

• posted

Dad used baling wire ... and IIRC 309 wire works well for tool/alloy steel to mild steel . Since I don't stock the proper shield gas to MIG it (I have .035 flux core 309 but it sucks) , I use the TIG . I also have some Invar 42 nickel/iron for cast iron and dissimilar metals , works well to attach SS "handles" to tungsten "mandrels" to make glass beads . A question about 7018 - as long as it's in the original container/packaging , do I need to be concerned with it picking up moisture ? I also have some "old" 7018 that's been exposed to ambient conditions for several years ... but since I'm the world's second worst stick welder it doesn't see much use . Especially since I bought a 220 volt Weldpak 175 MIG welder .

• posted

Did you remember flux core requires DCEN or does it really suck that bad? Even regular steel flux core does make a bit of a mess I admit.

I do really need to spend sometime welding test coupons with the TIG. I've used it successfully one time so far. Making an autogenous weld to secure a stainless pin in a stainless handle.

That's actually pretty impressive. At least to me it is.

I think I was politely told for the AWS Farm Code hackery I do it doesn't matter in the above post. That being said, I think the plastic slip tube containers do nothing to protect rod, but the giant tuna cans are completely sealed until opened.

... I think I just got called the worlds first worst stick welder. LOL. I can live with that.

it doesn't see much use . Especially since I bought a 220

• posted

My truck's 37 and I've only got one (yard) tractor ... but I've got 4 chainsaws . And I can hack with the best . You should see the cobbled cable bracket I'm making to mount an Edelbrock carb on the truck .

• posted

With a tractor-plough there is no risk to a weld holding on a hardened blade because it has no consequence - no-one could possibly get hurt where it happens in the middle of a plough during ploughing. We all evaluate risk. A repair on an excavator might be done frequently, all day every day, because if the part of repair fails no-one is in the digging zone of the excavator, ever. On a crane - never even thought about doing the same thing... Because if the crane failed it would for sure have seriously disasstrous consequences with a lot of people and property in the region the bad consequences could happen. So yes, we are discussing the obvious - yet what you get attuned to in this line of activity...

• posted

Yes and no.

Pick-up moisture? Yes it will happen. Unless it's a sealed "pull-ring" can - which only 6010's and 6011's come in *to keep moisture in! * Unless it's a still-sealed vac-pack which 7018's often come in. If your 7018's are in a cardboard packet, they'll have sucked-up as much moisture as they can...

Likely whisps of steam from the rod-oven :-)

I reckon oven-dried 7018's are nicer to use. Properly stored very Basic very traditional rods used by Babcocks who repair power-stations in the UK - you could read a newspaper through the arc it's so "clean and clear". Okay, but a hot quiver only which give much politer-behaving 7018's, I reckon.

• posted

Yes , I got the polarity right . It just kinda balls up without melting into the base metal . Might be because I didn't have enough amps available - this was with the Weldpak 100/110v machine , haven't tried the new one .

The hardest part for me is holding the arc length without dipping the tungsten in the melt puddle .

That was a little job for a bead maker here . Took a little experimentation to get the right combo , I started with 312/.050 filler . That sucked , so I tried the Invar . The lower melt temp worked better , but you better have a uniform bead or it will pull the mandrel out of line as it cools .

I ain't pointin' no fingers ...

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