Titanium stabilized quality inox tube please. Or maybe not…?
As you’d probably presumed from the name, this concerns a tube quality that was stabilized by using titanium. The titanium supplement prevents the excretion of chromium carbides which occurs when annealing the inox tubes at a temperature of 550-700°C. The excretion of chromium carbides causes the diminishing of corrosion resistance of the material and ultimately inter crystalline corrosion. This is fantastic you might think.
Reduced corrosion resistance in the welding seam
But a less well known phenomenon of this quality however is that the titanium compounds with the carbon and nitrogen in the material. And this compound unfortunately is not spread equally in the stripmaterial. The titanium compound can lead to oxide stains (or titanium stains) in the welding area with a Tig/Laser welding seam. And an agglomeration in the welding area during welding has a negative impact on the corrosion resistance of the welding seam with reference to the base material!
Low carbonated as a good alternative
An important alternative for the titanium stabilized qualities are the so called low carbonated qualities, namely Tp 304L / 1.4307 / 1.4306 for 1.4541 and 316L / 1.4404 for 1.4571. Because of the very low carbon grade, the chance of excretion of chromium carbides decreases drastically. Every modern blast furnace is able to produce these low carbonated qualities nowadays, unlike the fifties and sixties of last century.
Some other advantages of low carbonated qualities:
- Better availability
- Often lower pricing
- Better treatment when it comes to bending, grinding and polishing
Unfortunately the titanium stabilized qualities are firmly embedded in multiple product specifications of particurlarly heat exchanger tubes, used at large chemical plants. And it is hard to change that. We think this is a missed opportunity for a lot of companies. If you are hesitating whether or not low carbonated qualities are an alternative for your own practise, please don’t hesitate to contact us. We are glad you advice you or give you technical support.