Should Titanium Rust?

[appledell]

Just cleaned the bike and found my 1 month old Remus hexacone is going Rusty along the welded seam. This is the fully titanium one (including internals). i know titanium is difficult to weld, but shouldnt be getting rusty in a month?

hopefully the fonts of wisdom will let me know before I call motorworks.

 

[Fanum]

What colour is this 'rust' ?

Titanium oxide is white, just wondering if it's steel pop rivets or packing bands or something used in the weld on yours that's 'rusting'

My Titanium can oxidised, in the same way that ally panniers will, particularly in the winter when salt is abundant- lots of threads here about cleaning salt damage that you could apply in the same way to Titanium can

 

[appledell]

Its not oxidised, the rust is 'rust' coloured. The rest of the can is as new.

 

[Fanum]

Its not oxidised, the rust is 'rust' coloured. The rest of the can is as new.

If it's red/brown, it's not titanium, it's (probably) iron oxide of some sort that's come from the steel in the can, whether that be from pop rivets or something to do with the welding process.

Nearly all metals rust (oxidise) and will do so even faster in a salty environment (IE on winter roads)

I guess whether your rust is reasonable or not after a month depends on how bad it is and if there are any instructions from the supplier as to keeping it clean- or maybe there's damage to the weld that has allowed salty water to penetrate the weld and get to bits that it shouldn't have?

Check the seam out and see if it's intact or not maybe

 

[(RIP) Bin Ridin]

Maybe polished with a disc that has been used for ferrous metal....

 

[appledell]

will post pics tomorrow. The seam is intact. It better had be titanium with titanium internals !!!

It cost more and i had to wait 4 months for Remus to make it

 

[cookie]

maybe it's not welded with titanium & the weld's going rusty?

 

[Flipfly]

As per Mr Fanum.

It's not the Titanium that is red rusty. The welds thamselves can rust but it should only be surface.

As described above, many "non rusting" metals are simply metals that don't red rust. They oxidise and in the process of oxidisation, a clear protective coating is formed and the process starts over again. You will get pitting, but not necessarily red rust.

If it's the weld that's rusting, I'd just clean it off. If the Can itself is corroding on the titanium sheet, then that would be unusual.

I'm guessing that titanium being an alloy means there could be a ferrous content within the mixture?

 

[Fanum]

A bit of a poke around Google reveals that the Titanium alloy used in most exhausts is "Ti-1.5 Al" which does indeed contain iron, but only at less than a third of a percent by mass.

This red rusting on appledell's 'zorst ain't gonna be from that

 

[Wreford Miles]

The can may be titanium but the weld may not be if...

It's been made for hype more than technical reasons - Russians subs would not have rusted neither would high end mountain bikes but end cans sold by shops with big windows (so they can see you coming) may not need such attention to detail

 

[mike wright]

Ive many Ti parts on my mountain bikes inc hubs that have been used in all weathers and not cleaned for weeks. Never have I seen Ti rust.

 

[jez]

Titanium can only be welded to titanium, it's simply not possible to weld/solder any other metal to it.

 

[bmwrover]

If u weld higher quality stainless 316L, the weld will still rust if not passivated afterwards, same for Ti?

 

[Skid06]

i have a 10 year old ti mountain bike, left it outside for a whole winter no rust, i know what you mean about the wait for the remus ti hexacone i got fed up and got the carbon one and it looks fab

 

[Vern]

Titanium can only be welded to titanium, it's simply not possible to weld/solder any other metal to it.

Wanna bet

 

[jez]

note to self, must check my facts first

Welding Titanium

Titanium and most titanium alloys are readily weldable, using several welding processes. Properly made welds in the as-welded condition are ductile and, in most environments, are as corrosion resistant as base metal. Improper welds, on the other hand, might be embrittled and less corrosion-resistant compared to base metal.

The techniques and equipment used in welding titanium are similar to those required for other high-performance materials, such as stainless steels or nickel-base alloys. Titanium, however, demands greater attention to cleanliness and to the use of auxiliary inert gas shielding than these materials. Molten titanium weld metal must be totally protected from contamination by air. Also, hot heat-affected zones and root side of titanium welds must be shielded until temperatures drop below 800°F (427°C).

Titanium reacts readily with air, moisture, grease, dirt, refractories, and most other metals to form brittle compounds. Reaction of titanium with gases and fluxes makes common welding processes such as gas welding, shielded metal arc, flux cored arc, and submerged arc welding unsuitable. Likewise, welding titanium to most dissimilar metals is not feasible, because titanium forms brittle compounds with most other metals; however, titanium can be welded to zirconium, tantalum and niobium.

In spite of the precautions, which need to be taken, many fabricators are routinely and economically welding titanium, making sound, ductile welds at comparable rates to many other high performance materials. One of the important benefits of welding the commercially pure grades of titanium is that they are over 99% pure titanium and there is no concern for segregation. The same is true of weld wire or rod in commercially pure grades.

 

[Micky]

What colour is this 'rust' ?

Titanium oxide is white, just wondering if it's steel pop rivets or packing bands or something used in the weld on yours that's 'rusting'

My Titanium can oxidised, in the same way that ally panniers will, particularly in the winter when salt is abundant- lots of threads here about cleaning salt damage that you could apply in the same way to Titanium can

You aint found some rust on your 'bike have ya Bill

 

[Steptoe]

It's Nigerian titanium, well known for it's rusting qualities.

 

[boundless]

Corrosion of Titanium is pretty much unheard of in 'normal' atmospheric conditions:-

The excellent corrosion resistance of titanium alloys results from the formation of very stable, continuous, highly adherent, and protective oxide films on metal surfaces. Because titanium metal is highly reactive and has an extremely high affinity for oxygen, these beneficial surface oxide films form spontaneously and instantly when fresh metal surfaces are exposed to air and/or moisture. In fact, a damaged oxide film can generally reheal itself instantaneously if at least traces of oxygen or water are present in the environment. However, anhydrous conditions in the absence of a source of oxygen may result in titanium corrosion, because the protective film may not be regenerated if damaged.

The nature, composition, and thickness of the protective surface oxides that form on titanium alloys depend on environmental conditions. In most aqueous environments, the oxide is typically TiO2, but may consist of mixtures of other titanium oxides, including TiO2, Ti2O3, and TiO. High-temperature oxidation tends to promote the formation of the chemically resistant, highly crystalline form of TiO, known as rutile, whereas lower temperatures often generate the more amorphous form of TiO, anatase, or a mixture of rutile and anatase.

Although these naturally formed films are typically less than 10 nm thick and are invisible to the eye, the TiO; oxide is highly chemically resistant and is attacked by very few substances, including hot, concentrated HCl, H2SO4, NaOH, and (most notably) HF. This thin surface oxide is also a highly effective barrier to hydrogen.

 

[appledell]

Just take Photo's - not brill but you can see what I mean