Description
Stainless Steel 321 (UNS S32100) / Stainless Steel 321H (UNS S32109)
Stainless Steel 321 (UNS S32100) / 321H (UNS S32109) is stabilized stainless steel plate which offers as its main advantage an excellent resistance to intergranular corrosion following exposure to temperatures in the chromium carbide precipitation range from 800 to 1500°F (427 to 816°C). Alloy 321 /321H Stainless Steel Plate is stabilized against chromium carbide formation by the addition of Titanium.
321 / 321H Stainless Steel Plate is also advantageous for high temperature service because of its good mechanical properties. Alloy 321 / 321H Stainless Steel Plate offers higher creep and stress rupture properties than Stainless Steel 304 and particularly Stainless Steel 304L, which might also be considered for exposures where sensitization and intergranular corrosion are concerns.
General Properties :
Austenitic Stainless Steel 321 (UNS S32100) / 321H (UNS S32109) is Titanium stabilized Austenitic Stainless Steel Plate / Sheet with good general corrosion resistance. It has excellent resistance to intergranular corrosion after exposure to temperatures in the chromium carbide precipitation range of 800 – 1500°F (427 – 816°C). The 321 / 321H Alloy Plate & Sheets resists oxidation to 1500°F (816°C) and has higher creep and stress rupture properties than alloys 304 and 304L. It also possesses good low temperature toughness.
Stainless Steel Grade 321 / 321H Plates & Sheets is the higher carbon (0.04 – 0.10) version of the alloy. It was developed for enhanced creep resistance and for higher strength at temperatures above 1000oF (537°C). In most instances, the carbon content of the plate enables dual certification.
SS 321 / SS 321H Stainless Steel Plate & Sheets cannot be hardened by heat treatment, only by cold working. It can be easily welded and processed by standard shop fabrication practices.
Standards for SS321 / SS321H Plates & Sheets :
| ASTM | A 240 |
| ASME | SA 240 |
| AMS | 5510 |
Applications of SS 321 / SS 321H Grade :
| Aerospace – Piston Engine Manifolds | Expansion joints |
| Chemical Processing | Bellows |
| Expansion Joints | Furnace parts |
| Food Processing – Equipment and Storage | Heating element tubing |
| Petroleum Refining – Polyphonic acid service | Heat Exchangers |
| Waste Treatment – Thermal Oxidizers | Woven or welded screens for high temperature mineral processing |
| Pharmaceutical Production | Spiral Welded tube for burner pipes and flues |
| Aircraft exhaust manifolds |
Chemical Composition / Chemistry of Stainless Steel Grade 321 / 321H :
| Grade | C | Mn | Si | P | S | Cr | Ni | N | Other | |
| 321 | Min | – | 2.00 | 0.75 | 0.045 | 0.03 | 17.00 | 9.00 | 0.10 | T=5(C+N) 0.70 |
| Max | 0.08 | – | – | – | – | 19.00 | 12.00 | – | ||
| 321H | Min | 0.04 | 2.00 | 0.75 | 0.045 | 0.03 | 17.00 | 9.00 | 0.10 | T=4(C+N) 0.70 |
| Max | 0.10 | – | – | – | – | 19.00 | 12.00 | – |
Mechanical Properties of Alloy SS 321 / SS 321H Stainless Steel Grade :
| Grades |
Tensile Strength | Yield Strength 0.2%Proof | Elongation (% in 50mm) min |
Hardness | |
| Rockwell (HR B) | Brinell | ||||
| (MPa) min | (MPa) mm | (HR B) | (HB) | ||
| 321 | 515 | 205 | 40 | 95 max | 217 max |
| 321H | 515 | 205 | 40 | 95 max | 217 max |
Grade Specification Comparisons :
| Grade | UNS No. | Old British | Euronorm | Swedish SS | Japanese JIS | |
| BS | En | No. Name | ||||
| 321 | S32100 | 321S31 | 58E, 58C | 1.4541 X6CrNi18-10 | 2337 | SUS 321 |
| 321H | S32109 | 321S51 | – | 1.4878 X10CrNi18-10 | – | SUS 321H |
Corrosion Resistance :
Alloy 321 / 321H Stainless Steel Plate & Sheets exhibits good general corrosion resistance that is comparable to 304. It was developed for use in the chromium carbide precipitation range of 1800 – 1500°F (427 – 816°C) where un-stabilized alloys such as 304 are subject to intergranular attack.
The alloy can be used in most diluted organic acids at moderate temperatures and in pure phosphoric acid at lower temperatures and up to 10% diluted solutions at elevated temperatures. SS 321 / SS 321H resists Polythionic acid stress corrosion cracking in hydrocarbon service. It can also be utilized in chloride or fluoride free caustic solutions at moderate temperatures.
321 / 321H Stainless Steel Plate does not perform well in chloride solutions, even in small concentrations, or in sulfuric acid service.
Fabrication Data :
ASTM A240 Grade 321 /321H Stainless Steel Plate & Sheet can be easily welded and processed by standard shop fabrication practices.
Cold Forming :
The alloy is quite ductile and forms easily.
Machining :
The cold work hardening rate of SS 321 / SS 321H Stainless Steel Plate / Sheet makes it less machinable than 410 stainless steel, but similar to 304.
Welding :
SS 321 / SS 321H Stainless Steel Plate can be readily welded by most standard processes. A post weld heat treatment is not necessary. Excellent weldability by all standard fusion methods, both with and without filler metals. AS 1554.6 pre-qualify welding of SS 321 / SS 321H with Grade 347 rods or electrodes; high silicon version of 347 is also pre-qualified for welding of 321 / 321H.
Also called as :
| SS 321 Plates / Sheets / Coils | SS 321H Plates / Sheets / Coils |
| ASTM A240 321 Grade | ASTM A240 321H Grade |
| ASME SA240 321 Grade | ASME SA240 321H Grade |
| Alloy 321 Grade Plate / Coil | Alloy 321H Grade Plate / Coil |
| Jindal SS 321 Grade Plate / Sheet | Jindal SS 321H Grade Plate / Sheet |
| UNS S32100 Grade Plates / Sheets / Coils | UNS S32109 Grade Plates / Sheets / Coils |
| Stockist of Jindal SS321 Plate / Coil / Sheet | Imported Stockist of SS321H Plate / Coil / Sheet |
Possible Alternative Grades :
| Grade | Why it might be chosen instead of 321 |
| 304L | The requirement is for resistance to intergranular corrosion, not for high temperature strength |
| 3CR12 | Only mild “high temperature” environment is present up to about 600oC. |
| 304H | Only mild “high temperature” environment is present up to about 800oC. |
| 310 | The temp3erature of the operating environment is up to about 1100oC – too high for 321 or 321H. |
