321 Stainless Steel
This data sheet applies to stainless steel 321 / 1.4541 hot and cold rolled sheet and strip, semi-finished products, bars, rolled wire and profiles as well as seamless and welded tubes for pressure purposes.
1.4541
Application
Instruments and construction parts in the food industry, luxury food, film and photo industry as well as for articles of daily use in the household, power station construction. Due to the Ti-alloy, the resistance to intergranular corrosion is also guaranteed in the welded condition.
Corrosion resistance
Stainless steel 321 is equivalent to grade 304 in the annealed condition. It has superior corrosion resistance if a weldment in these grades has not been post-weld annealed, or if the application involves service in the 425-9000C range.
The alloy is subject to pitting and crevice corrosion in warm chloride environments and to stress corrosion cracking above 600C.
Heat resistance
Stainless steel 321 has good oxidation resistance in intermittent service to 9000C and in continuous service up to 9250C. This grade performs well in the 425-9000C range and particularly where subsequent aqueous conditions are present.
Heat treatment
Solution treatment involves heating to 950-11200C and cooling rapidly for maximum corrosion resistance.
For stabilising, the alloy is heated up to 870 - 9000C for one hour per 25mm of thickness and air cooled. Stabilisation is recommended for the most severe service conditions, particularly those above 4250C, and for materials annealed on the upper side of the annealing temperature range.
Chemical Compositions
| Element | % Present (in product form) | |||
|---|---|---|---|---|
| C, H, P | L | TW | TS | |
| Carbon (C) | ≤0.08 | ≤0.08 | ≤0.08 | ≤0.08 |
| Silicon (Si) | ≤1.00 | ≤1.00 | ≤1.00 | ≤1.00 |
| Manganese (Mn) | ≤2.00 | ≤2.00 | ≤2.00 | ≤2.00 |
| Phosphorous (P) | ≤0.045 | ≤0.045 | ≤0.0453) | ≤0.040 |
| Sulfur (S) | ≤0.0151) | ≤0.0301) | ≤0.0153) | ≤0.0151) |
| Chromium (Cr) | 17.00 - 19.00 | 17.00 - 19.00 | 17.00 - 19.00 | 17.00 - 19.00 |
| Nickel (Ni) | 9.00 - 12.00 | 9.00 - 12.002) | 9.00 - 12.00 | 9.00 - 12.002) |
| Titanium (Ti) | 5xC to 0.70 | 5xC to 0.70 | 5xC to 0.70 | 5xC to 0.70 |
| Iron (Fe) | Balance | Balance | Balance | Balance |
Chemical Compositions
| Element | % Present (in product form) | |||
|---|---|---|---|---|
| C, H, P | L | TW | TS | |
| Carbon (C) | ≤0.08 | ≤0.08 | ≤0.08 | ≤0.08 |
| Silicon (Si) | ≤1.00 | ≤1.00 | ≤1.00 | ≤1.00 |
| Manganese (Mn) | ≤2.00 | ≤2.00 | ≤2.00 | ≤2.00 |
| Phosphorous (P) | ≤0.045 | ≤0.045 | ≤0.0453) | ≤0.040 |
| Sulfur (S) | ≤0.0151) | ≤0.0301) | ≤0.0153) | ≤0.0151) |
| Chromium (Cr) | 17.00 - 19.00 | 17.00 - 19.00 | 17.00 - 19.00 | 17.00 - 19.00 |
| Nickel (Ni) | 9.00 - 12.00 | 9.00 - 12.002) | 9.00 - 12.00 | 9.00 - 12.002) |
| Titanium (Ti) | 5xC to 0.70 | 5xC to 0.70 | 5xC to 0.70 | 5xC to 0.70 |
| Iron (Fe) | Balance | Balance | Balance | Balance |
Mechanical properties (at room temperature in annealed condition)
| Product Form | Max Thickness (mm) | Yield Strength | Tensile Strength | Elongation min. in % | Impact Energy (ISO-V) ≥ 10mm thick | |||
|---|---|---|---|---|---|---|---|---|
| 0.2% Rp0.2 N/mm2 | 1% Rp1.0 N/mm2 | Rm N/mm2 | A1) %min (longitudinal) | A1) %min (transverse) | Jmin (longitudinal) | Jmin (transverse) | ||
| C | 8 | 2203) | 2203) | 520-7203) | - | 40 | - | - |
| H | 13.5 | 2003) | 2403) | 520-7203) | - | 40 | 100 | 60 |
| P | 75 | 2003) | 2403) | 500-7003) | - | 40 | 100 | 60 |
| L | 160 | 1904) | 2254) | 500-7004) | 40 | - | 100 | - |
| L | 2502) | 1907) | 2257) | 500-7007) | - | 30 | - | 60 |
| TW | 60 | 1805) | 2155) | 460-6805) | 35 | 30 | 100 | 60 |
| TS | 60 | 1805) | 2155) | 460-6805) | 35 | 30 | 100 | 60 |
Mechanical properties (at room temperature in annealed condition)
| Product Form | Max Thickness (mm) | Yield Strength | Tensile Strength | Elongation min. in % | Impact Energy (ISO-V) ≥ 10mm thick | |||
|---|---|---|---|---|---|---|---|---|
| 0.2% Rp0.2 N/mm2 | 1% Rp1.0 N/mm2 | Rm N/mm2 | A1) %min (longitudinal) | A1) %min (transverse) | Jmin (longitudinal) | Jmin (transverse) | ||
| C | 8 | 2203) | 2203) | 520-7203) | - | 40 | - | - |
| H | 13.5 | 2003) | 2403) | 520-7203) | - | 40 | 100 | 60 |
| P | 75 | 2003) | 2403) | 500-7003) | - | 40 | 100 | 60 |
| L | 160 | 1904) | 2254) | 500-7004) | 40 | - | 100 | - |
| L | 2502) | 1907) | 2257) | 500-7007) | - | 30 | - | 60 |
| TW | 60 | 1805) | 2155) | 460-6805) | 35 | 30 | 100 | 60 |
| TS | 60 | 1805) | 2155) | 460-6805) | 35 | 30 | 100 | 60 |
Reference data on some physical properties
| Density at 20°C kg/m3 | 7.9 | |
|---|---|---|
| Modulus of Elasticity kN/mm2 at | 20°C | 200 |
| 200°C | 186 | |
| 400°C | 172 | |
| 500°C | 165 | |
| Thermal Conductivity W/m K at 20°C | 15 | |
| Specific Thermal Capacity at 20°C J/kg K | 500 | |
| Electrical Resistivity at 20°C Ω mm2 /m | 0.73 | |
Reference data on some physical properties
| Density at 20°C kg/m3 | 7.9 | |
|---|---|---|
| Modulus of Elasticity kN/mm2 at | 20°C | 200 |
| 200°C | 186 | |
| 400°C | 172 | |
| 500°C | 165 | |
| Thermal Conductivity W/m K at 20°C | 15 | |
| Specific Thermal Capacity at 20°C J/kg K | 500 | |
| Electrical Resistivity at 20°C Ω mm2 /m | 0.73 | |
Coefficient of linear thermal expansion 10-6 K-1 between 20°C and
| 100°C | 16.0 |
|---|---|
| 200°C | 16.5 |
| 300°C | 17.0 |
| 400°C | 17.5 |
| 500°C | 18.0 |
Coefficient of linear thermal expansion 10-6 K-1 between 20°C and
| 100°C | 16.0 |
|---|---|
| 200°C | 16.5 |
| 300°C | 17.0 |
| 400°C | 17.5 |
| 500°C | 18.0 |
Processing / Welding
Standard welding processes for this steel grade are:
TIG-Welding
MAG-Welding Solid Wire
Arc Welding (E)
Submerged Arc Welding (SAW)
Laser Bean Welding
When choosing the filler metal, the corrosion stress has to be regarded, as well. The use of a higher alloyed filler metal can be necessary due to the cast structure of the weld metal. A preheating is not necessary for this steel. A heat treatment after welding is normally not usual. Austenitic steels only have 30% of the thermal conductivity of non-alloyed steels.
Their fusion point is lower than that of non-alloyed steel therefore austenitic steels have to be welded with lower heat input than non-alloyed steels. To avoid overheating or burn-through of thinner sheets, higher welding speed has to be applied. Copper back-up plates for faster heat rejection are functional, whereas to avoid cracks in the solder metal, it is not allowed to surface-fuse the copper back up plate.
This steel has an extensively higher coefficient of thermal expansion as non-alloyed steel. In connection with a worse thermal conductivity, a greater distortion has to be expected. When welding 1.4541 all procedures, which work against this distortion (e.g. back step sequence welding, welding alternatively on opposite sides with double-V butt weld, assignment of two welders when the components are accordingly large) have to be respected notably.
For product thicknesses over 12mm the double-V butt weld has to be preferred instead of the single-V butt weld. The included angle should be 60° - 70°, when using MIG-welding about 50° are enough. An accumulation of weld seams should be avoided. Tack welds have to be affixed with relatively shorter distances from each other (significantly shorter than those of non-alloyed steels), in order to prevent strong deformation, shrinking or flaking tack weld.
The tacks should be subsequently grinded or at least be free from crater cracks. 1.4541 in connection with austenitic weld metal and too high heat input the addiction to form heat cracks exists. The addiction to heat cracks can be confined, if the weld metal features a lower content of ferrite (delta ferrite). Contents of ferrite up to 10% have a favourable effect and do not affect the corrosion resistance generally.
The thinnest layer as possible have to be welded (stringer bead technique) because a higher cooling speed decreases the addiction to hot cracks. A preferably fast cooling has to be aspired while welding as well, to avoid the vulnerability to intergranular corrosion and embrittlement. 1.4541 is very suitbale for laser beam welding (weldability A in accordance with DVS bulletin 3203, part 3). With a welding groove width smaller than 0.3mm respectively, 0.1mm product thickness, the use of filler metals is not necessary.
With larger welding grooves a similar filler metal can be used. With avoiding oxidation within the seam surface during laser bean welding by applicable backhand welding, e.g. helium as inert gas, the welding seam is as corrosion resistant as the base metal. A hot crack hazard for the welding seam does not exist, when choosing an applicable process.
1.4541 is also suitable for laser beam fusion cutting with nitrogen or flame cutting with oxygen. The cut edges only have small heat affected zones and are generally free of micro cracks and thus are well formable. While choosing an applicable process the fusion cut edges can be converted directly. Especially, they can be welded without any further preparation. While processing only stainless tools like steel brushes, pneumatic picks and so on are allowed, in order to not endanger the passivation, it should be neglected to mark within the welding seam zone with oleaginous bolts or temperature indicating crayons.
The high corrosions resistance of this stainless steel is based on the formation of a homogeneous, compact passive layer on the surface. Annealing colours, scales, slag residues, tramp iron, spatters and such like have to be removed, in order to not destroy the passive layer. For cleaning the surface the processes brushing, grinding, pickling or blasting (iron-free silica sand or glass spheres) can be applied.
For brushing only stainless steel brushes can be used. Pickling of the previously brushed seam area is carried out by dipping and spraying, however, often pickling pastes or solutions are used. After pickling, a careful flushing with water has to be done.
Remark
In quenched condition the material can be slightly magnetizable. With increasing cold forming the magnetizability increases. Heat resisting tubes are delivered regarding testing in accordance to DIN EN 10296-2 respectively DIN EN 10297-2. In Germany, SEW 470 still applies for heat resisting tubes.
Editor
thyssenkrupp Materials (UK) Ltd
Cox’s Lane
Cradley Heath
West Midlands
B64 5QU
Important Note
Information given in this data sheet about the condition or usability of materials respectively products are no warranty for their properties, but act as a description. The information, we give on for advice, comply to the experiences of the manufacturer as well as our own. We cannot give warranty for the results of processing and application of the products.