4130 or T45 swing arm

[Oppet]

Hi all

Im figuring small project of making light swing arm for my BSA Scrambler. or maybe 1 year project
Few guestions first..

I have read that 4130 you can weld if its thin and not to heat treat it later, but one welder said that would be the worst materia for swing arm. I think he ment that it should anyway get treated. So, what have you to say about this??

another option is to make it with T45, but that is something very difficult to get in this country. This doesnt need heat treating so it would be "safe".

How I will be able to join these materials to mild steel?

TIG is what I will be using


O

 

[Sam]

T45 would be an easier meterial to work with and will be ok for you welding cr4 mild steel to it without any issues this can be sourced from Elmdon metals in the uk they also have several outlets globally that I am sure they would direct you too. Yes chrome molly (4130) does need normalising after welding some people recon you can do this with a bit of heat either side of the tube after welding but I have seen the failures of this process so personally I would not recommend it.

 

[hotrodder]

As Sam said T45 (doubt it'll make a difference but might be easier to locate using BST-4T45) is more forgiving but 4130 is used for countless thin wall fabrications without PWHT and no issues. Granted some people get it wrong by using a high strength filler and/or using tiny welds and the result is brittle but there's plenty of drag racing chassis, bicycles and the like out there that were not normalised after welding and have stood the test of time and crashing. Of course always hear more about the ones that break...

Welding 4130 has to got be one of the most debated subjects in internet welding history with all sorts of conflicting arguments, many based on stupid things like weld appearance and less based on engineering and metallurgy. A very good article on 4130 here

I'd still try and locate some T45 first, if it's particually hard to locate or pricey by comparison then go with 4130 and follow the advice in that article

 

[tigler]

Reynolds 531.

 

[Sam]

As Sam said T45 (doubt it'll make a difference but might be easier to locate using BST-4T45) is more forgiving but 4130 is used for countless thin wall fabrications without PWHT and no issues. Granted some people get it wrong by using a high strength filler and/or using tiny welds and the result is brittle but there's plenty of drag racing chassis, bicycles and the like out there that were not normalised after welding and have stood the test of time and crashing. Of course always hear more about the ones that break...

Welding 4130 has to got be one of the most debated subjects in internet welding history with all sorts of conflicting arguments, many based on stupid things like weld appearance and less based on engineering and metallurgy. A very good article on 4130 here

I'd still try and locate some T45 first, if it's particually hard to locate or pricey by comparison then go with 4130 and follow the advice in that article

Interesting article indeed have saved that one in the favourites section as you state I have seen or heard of more bad than good and was willing to accept not normalising properly as the main problem from credable welder fabricators so have always steered clear and used T45. I will give it a more indepth read when not so tired. Had also heard it was first oxy act welded but took that with a pinch of salt. Sam

 

[hotrodder]

4130 predates the invention of TIG, thicker sections or parts that'd be quenched and tempered aside oxy fuel was the method of choice for things like fuselages and still is in some circles (the EAA has/had some articles on the subject that i've failed to find with google). Forum discussions aside not a huge amount of freely available infomation on the subject and it's not an easy one to test without the right kit- welding some coupons (both processes, several different techniques with TIG to vary cooling times) and drilling a few holes or some file drawing can show differences in hardness but apparently fatigue testing can be quite an eye opener regarding small, low heat input TIG welds versus oxyfuel

Is Reynolds 531 still available? After being dropped it was 'custom order' only for a while but i thought it was unavailable now with T45 the closest thing, properties wise?

 

[tigler]

Is Reynolds 531 still available? After being dropped it was 'custom order' only for a while but i thought it was unavailable now with T45 the closest thing, properties wise?

Yeah , it is special only. 4130 & T45 are supposed to be the closest thing.
Apparantly 953 is now all the rage !! It's a maraging stainless steel ?!

 

[Arsonista]

You don't want any new fangled poncy stuff on a Beezer. You want the thickest heaviest steel you can get. That's what mine's made of anyway.

 

[pedrobedro]

Genuine Bitsas were made of old conduit and steam pipe

 

[tigler]

Amusing but not true. Most if not all Brit bikes were made of quality materials. Hence why there are lots of survivors.

 

[BChild]

Amusing but not true. Most if not all Brit bikes were made of quality materials. Hence why there are lots of survivors.

That and the engines are always oil tight so not much when rusty

 

[Oppet]

As you see Im not in hurry. I think now that I will make swing from 4130 tig welding and post stress relieving it with oxy acetylene at 1100F.
More stupid questions...
Can I mix 4130 with mild steel? As Im thinking also modyfien its frame, cut the back of the oil tank an make it little bit wider, so I can fit airbox better.
Ive allready put some effort on making my bike little bit lighter and better, cz rear and Rickman front wheels, betors, öhlins, seat, alu airbox and engine mods offcourse

Teppo

 

[pedrobedro]

You could use CDS tube and not have any problems to worry about at all. Like for like there is not that much strength difference and there is a limit to how much weight saving is practical before something becomes marginal for it's use. You can use ER70S-2 mild steel filler to weld 4130 so you should be able to weld it to mild steel.