316Ti Steel - 1.4571 - X6CrNiMoTi17-12-2 - S31635 - ~SUS 316Ti

316Ti stainless steel, like other austenitic steels is non-magnetic and cannot be hardened by heat treatment but hardens by cold working the material. It has very good corrosion resistance, excellent weldability and high durability, which helps in applications like furnace parts, heat exchangers, brewery equipment and medical implants or for the storage and transportation of e.g. milk.

Corrosion resistance

316Ti has good resistance to atmosphere, fresh water, fruit and vegetable juices and moderate resistance to diluted acids, like diluted sulphuric acid and hydrochloric acid and is also resistant to intergranular corrosion after welding.

Gas corrosion

316Ti can be used in air with temperatures up to 1560°F (850°C) and steam with temperatures up to 1380°F (750°C).

Corrosion resistance is reduced in sulphurous flue gases. In such environments, 316Ti

can be used at temperatures up to 1110-1380°F (600-750°C), depending on service conditions. Consideration must be given to weather the atmosphere is oxidizing or reducing, e.g. the oxygen content, and weather impurities such as sodium and vanadium are present.

Crevice/Pitting corrosion

With the added Molybdenum in 316Ti it can handle water with up to about 0.017lb/gal. (2,000 ppm) of chloride. Although considered adequate for some applications that are exposed to salt spray, it is not recommended in seawater containing 0.159lb/gal. (19,000ppm) of chloride.

Intergranular corrosion

With the addition of titanium the precipitation of chromium carbides in the grain boundaries can be prevented after prolonged heating in a temperature range of 840-1560°F (450-850°C).

Stress corrosion cracking

Austenitic steels are prone to stress corrosion cracking, as can be encountered at temperatures above 140°F (60°C) when the steel is exposed to tensile stresses or comes into contact for example with solutions containing chlorides at the same time.

Heat treatment

Annealing

To anneal, heat the work piece to 1868-2030°F (1020-1110°C), then cool in water or air.

Hardening

This steel grade can only be hardened by cold working the material.

Quenching

Quenching should be done in water for work pieces over ⁵/₆₄ inch (2 mm) at a temperature of 1868-2048°F (1020-1120°C) and air for work pieces under ⁵/₆₄ inch (2 mm).

Hot working

Heat the material to a minimum temperature of 1652°F (900°C) and do not let the temperature drop below this temperature. The ideal temperature range is between 2102-2300°F (1150-1260C), then cool in air after. To ensure the highest possible corrosion resistance afterwards annealing is recommended.

Cold working

Stainless 316Ti has good cold forming properties and are suited for brake and roll forming as well as stamping, heading and drawing. To reduce internal stresses a post work annealing is recommended. Cold working increases strength as well as hardness for this steel grade.

Machinability

To avoid excess work hardening keep the cutting edges sharp. Lubricants and coolants should be used liberally to avoid heat concentration at the cutting edges. Chip breakers should be employed to keep the work piece clear.

Forging

Heat the work piece to approx. 2102-2156°F (1150-1180°C), forging takes place at the temperature range of 2156-1742°F (1180-950°C) followed by air or water cooling.

Welding

Stainless steel 316Ti can be welded with most common welding methods with or without fillers. Gas welding should be avoided as this will risk carburization. A heat treatment is not necessary after welding and tempering colors should be removed chemically or mechanically to maintain the best possible corrosion resistance.

Fabrication

To avoid cross contamination while fabricating, only tools dedicated to stainless steel materials should be used to avoid surface discoloration of the fabricated products. Clean all tooling and work surfaces thoroughly against cross contamination as well.