Hot rolled angle problems

[SillyOldDuffer]

On SillyOldDuffer Said:

 

Something odd going on with reports of poor steel quality and I note they mostly originate from small workshops or the internet, not large-scale steel consumers like car-makers or shipbuilders.

 

When I worked in a car factory and a shipyard (submarines), they were both very selective about who they bought their steel from, for production use and toolroom/machine shop use, based on research, testing and experience.  There is a wide variation in quality between sources. Steels ain’t just steels.

 

 

[DiogenesParticipant @diogenes]

I’ve never had ‘bad’ steel from any of ‘the usual’ suppliers – has anyone here had definite, discrete, identifiable ‘inclusions’ in their steel.?

[JasonBModerator @jasonb]

I’ve had a couple of bits of EN3 with something nasty lurking inside that just took the edge off the HSS cutter that first made contact, even had difficulty with carbide and blunted a couple in the process of completing the parts. Nothing visible so unlikely to be refactory. Worse than chill in an iron casting.

I suppose that if what you get if you throw your inserts away with your swarf/waste/household rubbish. The big magnet on the end of the crane won’t know if it is leaded EN1A or an insert and just drop it in the pot!

[Taf_PembsParticipant @taf_pembs]

Nothing to add other than if you can, go and see the stock before purchase unless its a supplier you trust to send decent stuff. It is really frustrating when you get some poor stock and often you have started on it so cant send it back.

That really does look poor though, cant say I’ve ever had any that bad.

Not an advert, just had decent stuff is F H Brundle, they seem to be doing a lot more steel stock now and the last stuff I had was excellent.

 

You have to hand it to China though, they have played a bit of a blinder!

Undercut the rest of the worlds steel supply (with significant subsidies) for a decade or so until the rest of the world can no longer sustain the competition – even if what is being produced is largely of suspect quality.

Rest of the world begins to fail, closing steel works at an alarming rate and hay presto (there we go, advertising again!) they have almost complete market share.. and lets see what happens to prices and quality (well, quality is debatable anyway!) now they have pretty much completed their plan.

 

Look what we have done to Port Talbot.. closing both blast furnaces – ‘Great’ you can hear all the pollution watchers shouting, ‘Electric Arc furnace’s are Greener’ – well, no, they are going to cause more pollution .. just not in this country as they can not make virgin steel, only recycle scrap. So more virgin steel will be made in chinese blast furnaces then shipped here .. more pollution not less! and we all know what most of chinese pollution regulations work like.

 

Sorry, complete hijack there.

[noel shelleyParticipant @noelshelley55608]

Hey Taf, your comments about Port Talbot apply to many industries, pollution is not being reduced just moved, and costing US a fortune ! Noel.

[Mick BaileyParticipant @mickbailey28509]

Noel, Thanks for the offer – I’m in N.Staffs. I need two pieces to finish at 7.25″.

I don’t expect precision with BMS but there’s an acceptable compromise to be had that the piece that I have doesn’t meet. Maybe it’s a special section specified for a purpose I’m not aware of. Most of the angle I use either has a square corner, or in larger sizes a small radius. I expect that there may be a tapering in section or variation from a nominal size, or rolling marks that affect the finish. I did a random check of my 10mm BMS flat though, and it’s all very close to size.

How I look at it is an assembled BMS construction in model making is something I’d use as a substitute for a casting and once bolted or welded together is machined as such.

[Nigel McBurney 1Participant @nigelmcburney1]

I bought a 6m length of 50 x 6 black hot rolled last year for a stationary engine trolley when drilling holes the drill bits made sharp crackly noises when drilling various sizes of holes and putting a full rad on one end  took about a foot length of teeth off my band saw blade, the steel came from a well known south coast supplier,though do not know where it came from originally.

[Mick BaileyParticipant @mickbailey28509]

To continue with my hot rolled angle saga….

I was given a length of nice looking BMS angle last week – nominally 6″x4″x3/8″, and generously sized on the thickness. It cut down nicely with 1mm cutting discs in my angle grinder, but i found it to be more difficult to machine than expected.

Having made a slight error due the the work moving in the milling vice, I had a very slight gouge. No problem, just weld it over, grind down and re-machine. With BMS I’ve never once had a problem machining weld material. The cut proceded nicely, got to the weld spot and the sound suddenly changed. Instead of cutting there was just a polished high spot and a spoilt cutter. Having checked the spot it appears to be glass hard, indicating perhaps a higher carbon content in the angle.

The final thing last night was to anneal the piece and today will see if its machinable.

 

[SillyOldDufferModerator @sillyoldduffer]

Problem with BMS is that it isn’t a single specified steel, and it has a bunch of properties that make it risky in the workshop.  Bright Mild Steel describes the result of a finishing process, not a particular metal.  BMS is made by cold-rolling and drawing any of several mild-steels, plus possibly soaking the result in acid to improve the polish.  Jokers are wild unless the seller explains, or you buy to a specification.

Converting mild to BMS changes the original steel considerably:  tensile strength is improved, but the BMS version becomes less ductile and is likely to be stressed internally.  If BMS is machined, these stresses redeploy in ways likely to warp the material. If the BMS was made from a free-cutting mild-steel the Sulphur or Lead used in them makes welding even trickier.

BMS is intended for structural purposes, not milling, turning, bending or welding.  Although I use BMS a lot because it saves time, it’s always a bit risky. I mostly get away with machining it.  Not always…  There’s a case for never using BMS as I do because BMS is unreliable for that kind of work.  Ordinary hot rolled mild-steel avoids all these problems and is cheaper too.  But it’s poorly finished and the dimensions aren’t accurate.  Nothing is ever easy!

How was the weld done?  My guess is the problem is Nitriding and the Nitrogen came from the air.   Nitrides are HARD, and I don’t know if they can be softened by annealing.  Just a guess though – please report back!

Dave

 

 

 

[Michael GilliganParticipant @michaelgilligan61133]

For what it’s worth … F.H. Brundle quotes a specific grade:

https://www.fhbrundle.co.uk/products/300430305__Rolled_Steel_Angle_30x30x5mm_x_6.0-6.1m_Equal_Angle_Grade_S275

MichaelG.

.

Edit: __ Some useful info. here:

https://www.steelexpress.co.uk/structuralsteel/S355-S275-structural-steel.html

[Diogenes]

On Diogenes Said:

I’ve never had ‘bad’ steel from any of ‘the usual’ suppliers – has anyone here had definite, discrete, identifiable ‘inclusions’ in their steel.?

Yes.  Had some 50 x 12 BDMS with laminations toward one end from ebay.  Laminations were about 1mm deep.  The seller did replace the piece.

Martin

[Mick BaileyParticipant @mickbailey28509]

The steel isn’t bad – just unexpected that it welded up hard. I used MIG with argon/co2 mix and good gas flow, so nitriding may not be the reason. Today’s workshop session looks like it’s been derailed due to other matters, but I’ll report back when I get chance to see if annealing solves the problem.

This of course is the peril of gift materials with no real provenance.

The only time I can recall a problem with steel was a length of 4″x1/8″ bright steel flat from a reputable supplier that had an edge that had been folded over during rolling and had oxide trapped in the fold. As it was being cut down I didn’t exchange it.

 

[Tim StevensParticipant @timstevens64731]

I am disappointed that a moderator should write such offensive tosh.

[Mick BaileyParticipant @mickbailey28509]

The hard spot was fine after annealing and I subsequently tested a sliver of the material to see if it would harden when quenched from red heat and it does, so it’s not mild steel. I also noticed it work hardens very quickly.

[BazyleParticipant @bazyle]

Some interesting comments on experience with ‘weld then machine’. My understanding (from reading here mostly not having welded myself) was that the weld bead itself was always hard and nearby material likely to be hardened if it contained carbon ie all steel which is why model engineers preferred solder/braze techniques.

[Mick BaileyParticipant @mickbailey28509]

I’ve only experienced hard, unmachinable welds in high carbon steels (using rods or wire intended for mild steel). A hard bead is likely to fracture, especially in thin sheet metal where the bead cools quickly.

A high carbon steel forms an indeterminate alloy with the rod/wire that then has a higher carbon content than the filler material. With a low carbon steel and compatible filler material, the alloying is mitigated  leaving a ductile weld.

For model engineering , mostly the assemblies that are soldered or brazed are unsuited to welding due to materials, precision, scale or design. As model size increases there’s a greater opportunity to weld, such as building steel rather than copper boilers, or welded up flywheel assemblies etc.

 

[duncan webster 1Participant @duncanwebster1]

It’s all a matter of how much carbon. Low carbon steels such as EN3 and S275 have less than 0.3%, and won’t give problems with hardness/cracking if you use the right rods. EN8 has 0.4%, and can give problems if you don’t take precautions. Best avoided unless you know what your doing.

Two of my locos have frame stretchers fabricated by welding. You have to machine after as you always get a bit of distortion.

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