T45 welded rollcage

[Gasman]

I recently had an enquiry regarding T45 steel (a preferred grade in the UK for motor sport roll cages) I believe it is higher in chrome/magnesium than mild and requires welding with different wire/rods.

They will need to weld T45 to T45 & to a mild steel chassis with a combination of MIG & TIG.

If anyone knows of the correct materials & gas I would be most grateful for some input.

Many Thanks

 

[paul33]

Best to talk to Elmdon Metals 01604670992 they are the only people for T45 and very helpful. cheers

 

[Gasman]

Problem solved thanks to paul33, Just spoke to Phil who's knowledgeable and very helpful indeed.

For future reference, It was explained that a Sif bronze Tig rod (used with straight argon) is the correct method.

They can also be found at www.elmdonmetals.co.uk

 

[Shox Dr]

Sifsteel A15 or A18 at a push, not sure bronze rod would pass regs as it needs to be welded, not in effect Brazed all be it using TIG as a heat source

 

[Gasman]

Have done a bit of research but correct me if I'm wrong....I believe the theory is that the welded/brazed joints maintain some ductility rather than the joint being tougher than the parent metal in this case.

It now makes sense that folk I know who braze custom bike racing frames apparently do so because it improves the handling.

 

[Shox Dr]

very true, however, Im sure the regs state it has to be welded

 

[hotrodder]

Bottom line is that rollcage joints will have to conform with the regs. As Shox Dr said, that means welding (sometimes even the process is restricted too) only AFAIK

Welding with an er70 type filler (A15 etc) is normal for T45 and 4130 tubing when it'll be used 'as welded'

 

[viktorm]

T45 rollcage welding

Hello!

I need to know which kind of welding is the best for a t45 rollcage, also the required equipments and consumables. I did a research about it, but i found more options: tig and mig, A18/A31/A32 filler rod. Now i'm a little confused and fed up with finding it out from little parts of information at forums. Could you help me with this?

 

[Sean]

You need to ask the governing body for the branch of motor sport this cage is for, most state "MSA Blue book" which is difficult to get a look at unless you join the MSA. I think most of the regs are now in line with FIA which means everything from your pants outwards has to be approved and dated!

Cage will be welded( not braized, soldered or glued), front and main hoop will be single piece.
It would be a shame to spend money and time on prep only to be turned down by the scrutineers at the first event

edit- just read the rest of the thread-there was a good link to a manufacturer recently along with a You tube of the in situ welding, im sure the company would be able to advise on preferred method and wire/filler. you also had to weld a test piece for return to the company before they would issue a certificate.

me - i stick to the easy stuffhere

 

[Luke]

The MSA yearbook is available online, see this link

 

[rocketron]

If you're doing MSA sanctioned events, then it has to be welded. NO BUTS!
Anyone who rallies or races will have a MSA blue Book, they're new and free with new competition licence every year. You could borrow last year's!!!!
They've not changed a lot. Possibly on line at msauk. Or find a scrutineer whose any good: not all of them are. Or ask here. You can buy direct from MSA, prob about £28.
The blue Book is a good guide to rollcages, it continually evolves and a new version every year. Be warned some bits have been accidentally omitted, ie, "all welds to be circumferrentially welded". Obvious to many, unfortunately not to all.
The blue book will NOT tell you what filler rod to use, except "use the correct one". Common sense dictates T45 filler for T45 cages, but what filler do you use for T45 tube to its mounting foot (different material?), the mounting foot to the re-inforcing plate ( whose size is important for MSA, again material/welding compatability with its neighbour, is often omitted even by professional teams, and is required!), and the re-inforcing plate to bodyshell ( different materials again). As an installer this is your responsibility.
You need to be armed with the various info, ask tube manufacturers, welding specialists etc. Be wary of info not supplied with documentary proof.
Or you can gung-ho weld it, like many teams do and hope some tw_t scrute doesn't spot anything. Most are lucky, many are not!
Before installation, for chrissake, PLAN your direction first, even if it takes weeks, cos with a "fully weld" in cage from a bag of tubes can be a nightmare of a job, even more so if you got to make corrections.
In the last few years I've only passed 3 weld in cages that have not had any faults at first inspection, and all were fitted by the same installer.
Last week, I inspected a weld in cage migweld fitted by an installer who had worked for P'drive, Rallixxt and a company who now builds historic Mk1 escorts, none of which cost less than £100K. It failed cos it had undersize re-inforcing plates and even those for the backstays were missing. His workmanship was exemplary, much better than mine, but I understand the Bluebook a little better, and its tw_ts like me you got to satisfy, post build or later in the car's competition life. I do not take pleasure in deflating builders' ego, but I do appreciate top quality workmanship and skill.
There are concerns mentioned that some tig weld cages have later shown some worrying cracks; I have not seen any to date.
There arer also concerns that some tig welded cages , although looking good have shown very small fillets. I'm no weld inspector, but when I see tig fillets considerably smaller than on my tig welded steel mountain bike, from some back yard shed in India, I think I should be worried. Have seen several weld fractures on tigged cages, at surprising low velocity impacts.
Give me a factory made bolt up,( I didn't say Safety Devices, did I?) above many weld up kits.

So plan, ask and do a good job. We really do appreciate it.

So will your customer, and so will your reputation.
Best of luck.

 

[BeeJay99]

The subject of roll cages takes up many pages of the regulations and to avoid making expensive mistakes it might be a good idea to beg, borrow or steal a copy of the Blue Book. All aspects are covered, from dimensions, cross members, chassis mounting etc. but relevant to this thread on materials and welding I found the following paragraphs. It may be that a specific formula may demand a higher specification but the basic requirements are...

From the 2011 Blue Book (K) Competitor Safety, Roll Over Structures

Technical specification.

1.3.8 Guidance on welding. All welding should be of the highest possible quality with full penetration and preferably using a gas shielded arc. Although good external appearance of a weld does not necessarily guarantee its quality, poor looking welds are never a sign of good workmanship. When using heat-treated steel the instructions of the manufacturer must be followed (special electrodes, gas protected welding). It must be emphasised that the use of heat-treated or medium carbon steels may cause problems and that bad fabrication may result in a decrease in strength (caused by brittle heat-affected zones) or inadequate ductility.

Material specifications

1.4.1 Specifications of the tubes used.

Minimum material
Cold Drawn Seamless Carbon Steel

Minimum Yeild Strength
350 N/mm²

Minimum Dimensions (ø in mm)
45 x 2.5 or 50 x 2.0
38 x 2.5 or 40 x 2.0 (For roll cages.bars approved prior to 1.1.95).

1.4.2 In selecting the steel attention must be paid to obtaining good elongation properties and adequate weldability.

1.4.3 The tubing must be bent by a cold working process and the centreline bend radius must be at least three times the tube diameter. If the tube is ovalised during bending the ratio of minor to major diameter must be 0.9 or greater.

 

[stuvy]

Rocketron and Beejay have a pint on me thats two of the most honest and useful posts iv read in a long time, well since i read Baloo's tube bender build

 

[hotrodder]

The blue book will NOT tell you what filler rod to use, except "use the correct one". Common sense dictates T45 filler for T45 cages, but what filler do you use for T45 tube to its mounting foot (different material?), the mounting foot to the re-inforcing plate

It's not as straightforward as using the same material for filler wire for a 'best match'. The usual argument for this sort of things goes along the lines of T45 (or 4130 chromoly for those that can't round corners) are 'stronger' than mild steel so you need to use a high strength wire. The counter argument begins with stronger generally = harder = less ductile. Mechanical properties of the three usual suspects are here...

A15... http://www.midalloy.com/html/pdf/low_alloy/Midalloy%20ER70S-2.pdf (A18 is very similar but kinda optimised more for MIG)
A31... http://www.midalloy.com/html/pdf/low_alloy/TB%20ER80S-D2%20Weld.pdf
A32... http://www.midalloy.com/html/pdf/low_alloy/TB%20ER80S-B2%20AND%20EB2%20Weld.pdf
Another source here... http://www.westbrookwelding.co.uk/tig/chrometig.html, A15 and A18 are under TIG mild steel

If we were talking thick material or butt welds or PWHT (post weld heat treatment) it'd be different but rollcages and the like = fillet welds on tube with a wall thickness of 2-3mm used 'as welded'. Article on fillet welds here... http://www.twiprofessional.com/content/jk91.html Undersize welds will only be an issue if using TIG and purposely producing tiny welds (small dia wire and barely using any). In other words if welded properly the undermatch of a ductile mild steel wire will be compensated by the weld cross section. Another article, specifically about 4130 tube chassis but still relevant... http://www.netwelding.com/Welding%204130.htm IIRC TechnicAl has mentioned in the past going through a similar thing as the author but with the Ford WRC team

Personally i'll stay with an er70 type wire paying attention to things like weld size and profile. For those that must use a stronger wire A31/er80s-d2

 

[rocketron]

Thanks Stuvy for the kind remarks. Hotrodder's posting is very interesting and WAY above my head, but will give it some study as background information. As a scrute, I know that welding stuff is extremely complex and involved, but I'm not expected to know why. But I know what the MSA expects. The MSA often consults the Welding Institute and I'm certain there is a member on the Technical Commission.
It's wonderful to see a forum that "works". With all this info from different directions is how problems are simplified.

 

[Robotstar5]

I've seen a car impounded by the MSA for "technical investigation" after it sideswiped a treestump and the side intrusion bar broke injuring the co-driver.

 

[viktorm]

Thank you very much for your help!