Titanium Submarine

[Oublious]

If you are number 1 exporter of titanium why not making it from titanium. Corrosion resistance and non magnetic .

 

[OPTIMUS]

the submarines made of titanium have its pitfalls and disadvantages. And they are not unimportant.

 

[Oublious]

the submarines made of titanium have its pitfalls and disadvantages. And they are not unimportant.

what kind pitfalls are we talking about.

 

[OPTIMUS]

Titanium and steel bodies behave differently under pressure. A Titan submarine can afford how many submersions and emerges? Or how do titanium bodies behave during repeated depth changes? I tell you very badly.
We know that some Russian Titan submarines have already operated 1600m deep. But every diving maneuver for a Titan submarine is a suicide for material. No matter what depth.

 

[Nilgiri]

Titanium and steel bodies behave differently under pressure. A Titan submarine can afford how many submersions and emerges? Or how do titanium bodies behave during repeated depth changes? I tell you very badly.
We know that some Russian Titan submarines have already operated 1600m deep. But every diving maneuver for a Titan submarine is a suicide for material. No matter what depth.

You are talking about no fatigue limit for S-N curve right? (Unlike that which steel has below a certain experienced stress)

It is true but a secondary issue more or less as you can take this into account (it is how we use aluminium alloys in several mainstream aerospace load bearing applications for example).

Moreover while there is no clear horizontal profile below a certain stress (like Steel), there is something of a horizontal asymptote (quite unlike Aluminum alloys which decline quite noticeably in this area):

From: https://www.researchgate.net/figure/SN-curve-of-Ti6Al4V-alloy_fig2_285384606

i.e not as great as Steel is in this arena, but certainly nowhere as bad as Aluminium is.

The primary issues with Titanium alloys reside with their shaping (at this size), machinability and weldability issues at this scale.

This makes Titanium extremely expensive to manufacture reliably at this scale and also creates compounding problems on some issues* in each case (for something where it is the entire load bearing hull essentially).

You need to do lot of capital machinery RnD specifically for Titanium at this scale and also be ready to take the hits (on cost and certain design compromises) for only some relative gain on some parameters to a more conventional steel hull.

Stealth acoustic tiles (already expensive) for example have (IIRC) had compounded issues with Russian titanium hulls given the issues with mating them with Titanium and how certain properties crop up there. i.e You just don't want extra downtime on critical assets like Submarines.

These have combined to make Titanium hull somewhat a relative novelty/peculiarity in military submarine evolution overall.

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