Advantages of Stainless Steel Factors that favor stainless steels selection as heat exchanger material over Aluminium include the following:
- High resistance to uniform corrosion
- Resistance to oxidation
- Suitability for intended fabrication techniques such as forming and welding
- Toughness at cryogenic temperature and strength at elevated temperatures
- Resistance to galling and seizing
- Dimensional stability under thermal load
Grade 316Ti is similar to Grade 316L except that 316Ti has better high temperature strength, and mechanical strength. It is used for equipment exposed to aggressive corrosive conditions and high temperature applications including automotive flexible connectors, welded bellows, chimney liners, and flexible ducting.
It 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.
This grade is essentially a standard SS 316 type with titanium stabilization and is similar in principle to the titanium stabilization of the SS Type 304 to produce Type 321. The addition of titanium is made to reduce the risk of intergranular corrosion (IC) following heating in the temperature range 797-1499 °F. 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 Type 316Ti and 316 /316L can be assumed to be similar. Neither of the grades can be expected to weld ‘easier’ or ‘better’ than-the-other. Niobium stabilized fillers (welding consumables) should be used for welding the 316Ti, 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’ 316Ti material.
Werkstoff Number for Stainless steel types 316 and 316L are 1.4401 and 1.4404 respectively. Grade 316 is an austenitic grade second only to 304 in commercial importance. 316 Type 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 (sensitization). 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 stabilized 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 ASME BPVC 2017 Section IX SA240/SA240M.
ASME BPVC Section IX 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 stabilize the structure of the 316 at temperatures over 1472 °F. 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 sensitization (precipitation) occurring. 316Ti retains physical and mechanical properties similar to standard grades of 316.