316TI pipe welding. Need help

[Brytawney]

Ooo

[wmgeorge]

I have to do a repair job and a brazing furnace here at work. The pipe that needs welded is TP316TI stainless. The added titanium seems to be tricky part. We had a company turn down the repair job because of the type of material. My questions would be, what type of filler to use(searched online and found 316L)? Any tips or precautions I should take? And should the pipe be back purged?

So a professional welding shop or pipefitters turned the job down and your going to do it? How much experience do you have in welding stainless pipe let alone titanium do you have? If the weld fails what kind of bad thing will happen?

[Burnt hands]

Here is a bit of info on 316ti.

It would seems that 316ti welds much like 316.

This company makes cooking pots using 316ti.
Marketing hype or will it make my meatloaf taste like filet mignon?

http://saladmaster.com/index/Products/WhatIsSolutionsTi.nws

Good luck.



AISI 316Ti 1.4571 Stainless Steel

Alloys 316Ti 1.4571 Similar to Grade 316L except that 316Ti has better high Temperature strength, and mechanical strength. Used for equipment exposed to aggressive corrosive conditions and high temperature applications,including automotive flexible connectors, welded bellows, chimney liners, and flexible ducting.

Type 316Ti 1.4571 is an improved corrosion resistant Chrome-Nickel steel alloy with high content of Molybdenum and some Titanium. It is not a typical free machining grade and therefore not recommended for difficult high speed machining process.Grade 316Ti stainless steel has been traditionally specified by German engineers and users with the Werkstoff number 1.4571.The former steel grade in the UK was 320S31.

This grade is essentially a standard carbon 316 type with titanium stabilisation and is similar in principle to the titanium stabilisation of the 304 (1.4301) type to produce 321 (1.4541). The addition of titanium is made to reduce the risk of intergranular corrosion (IC) following heating in the temperature range 425-815C. The addition of titanium reduces the risk of IC since titanium carbo-nitrides are formed in preference to chromium carbides which has the effect of maintaining the correct distribution of chromium throughout the structure of the steel.

The weldability of the 1.4571 and 1.4404 / 1.4432 can be assumed to be similar. Neither of the grades can be expected to weld 'easier' or 'better' than-the-other. Niobium stabilised fillers (welding consumables) should be used for welding the 1.4571, especially where elevated temperature weld strength may be important. In
other circumstances a '316L' filler should give a matching weld metal aqueous corrosion resistance to that of the 'parent' 1.4571 '316Ti' material.

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Stainless Steel - Austenitic - 1.4571 Bar

Stainless steel types 1.4401 and 1.4404 are also known as grades 316 and 316L respectively. Grade 316 is an austenitic grade second only to 304 in commercial importance.316 stainless steel contains an addition of molybdenum that gives it improved corrosion resistance. This is particularly apparent for pitting and crevice corrosion in chloride environments. 316L, the low carbon version of 316 stainless steel, is immune to grain boundary carbide precipitation (sensitisation). This makes it suited to use in heavy gauge (over about 6mm) welded components.

For elevated temperature applications the high carbon variant, 316H stainless steel and the stabilised grade 316Ti stainless steel should be employed.

The austenitic structure of 316 stainless steel gives excellent toughness, even at cryogenic temperatures. Property data given in this document is typical for flat rolled products covered by ASTM A240/A240M.

ASTM, EN or other standards may cover products sold. It is reasonable to expect specifications in these standards to be similar but not necessarily identical to those given in this datasheet.

Stainless steel grade 316Ti contains a small amount of titanium. Titanium content is typically only around 0.5%. The titanium atoms stabilise the structure of the 316 at temperatures over 800°C. This prevents carbide precipitation at the grain boundaries and protects the metal from corrosion. The main advantage of 316Ti is that it can be held at higher temperatures for a longer period without sensitisation (precipitation)
occurring. 316Ti retains physical and mechanical properties similar to standard grades of 316.

Chemical Composition

Chemical Element % Present
Carbon (C) 0.0 - 0.08
Chromium (Cr) 16.00 - 18.00
Molybdenum (Mo) 2.00 - 3.00
Silicon (Si) 0.0 - 0.75
Phosphorous (P) 0.0 - 0.05
Sulphur (S) 0.0 - 0.03
Nickel (Ni) 10.00 - 14.00
Titanium (Ti) 0.0 - 0.70
Iron (Fe) Balance
NB: Minimum Titanium content is 5 x (%C + %N)
Properties

Physical Property Value
Density 8.0 g/cm³
Melting Point 1400 °C
Thermal Expansion 15.9 x10^-6 /K
Modulus of Elasticity 193 GPa
Thermal Conductivity 16.3 W/m.K
Electrical Resistivity 0.074 x10^-6 O .m
Mechanical Property Value
Proof Stress 170 MPa
Tensile Strength 485 MPa
Elongation A50 mm 40 %
Alloy Designations

Stainless Steel Grade 1.4571/316Ti also corresponds to the following designations but may not be a direct equivalent:

UNS S31625
320S31

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[snoeproe]

No offense but...
Your question of "should it be backpurged"? makes me believe you shouldnt be welding this.