Description
SS 321 / 321H Round Bars
SS 321 / 321H Round Bars is a titanium stabilised chromium-nickel austenitic stainless steel with good strength and excellent corrosion resistance, as supplied in the annealed condition.Characterised by high corrosion resistance in general atmospheric corrosive environments it exhibits excellent resistance to most oxidizing agents, general foodstuffs, sterilizing solutions, dyestuffs, most organic chemicals plus a wide variety of inorganic chemicals, also hot petroleum gases, steam combustion gases, nitric acid, and to a lesser extent sulphuric acid. It displays good oxidation resistance at elevated temperatures has excellent resistance to intergranular corrosion and has excellent weldability. 321 cannot be hardened by thermal treatment, but strength and hardness can be increased substantially by cold working, with subsequent reduction in ductility.
SS321 is the basic 18/8 austenitic steel (Grade 304) stabilised with Titanium. This grade is not sensitive to intergranular corrosion after heating within the carbide precipitation range of 425-850°C. 321 is the grade of choice for applications in the temperature range of up to about 900°C, combining high strength, resistance to scaling and phase stability with resistance to subsequent aqueous corrosion.
SS321H is a modification of 321 with a controlled higher carbon content, to provide improved high temperature strength.
A limitation with 321 is that titanium does not transfer well across a welding arc, so is not usable as a welding consumable.
Like other austenitic grades, 321 has excellent forming and welding characteristics, is readily brake or roll formed and has outstanding welding characteristics. Post-weld annealing is not required. Grade 321 also has excellent toughness, even down to cryogenic temperatures.
Chemical Composition of SS 321 (1.4541) / SS 321H (1.4878) :
| Elements | 321 | 321H | ||
| Min. % | Max % | Min. % | Max % | |
| Carbon | – | 0.08 | 0.04 | 0.10 |
| Silicon | – | 1.00 | – | 1.00 |
| Manganese | – | 2.00 | – | 2.00 |
| Nickel | 9.00 | 12.00 | 9 | 12.00 |
| Chromium | 17.00 | 19.00 | 17.00 | 19.00 |
| Titanium | 5 x Carbon | 0.80 | 4 x Carbon | 0.80 |
| Phosphorous | 0 | 0.045 | 0 | 0.045 |
| Sulphur | 0 | 0.030 | 0 | 0.030 |
Applications of SS 321 / 321H Round Bars :
- • Aerospace – piston engine manifolds
- • Chemical Processing
- • Expansion Joints
- • Food Processing – equipment and storage
- • Petroleum Refining – polythionic acid service
- • Waste Treatment – thermal oxidizers
