Stainless steel 321
Grade 321 stainless steel (1.4541) is a heat resistant grade supplied into numerous industry sectors. The key property of this grade is the added titanium content (5 x C%) stabilising the material and making its resistance to carbide precipitation when exposed to high temperatures and resistance to oxidation its main characteristics. Whilst retaining good strength and corrosion resistance when exposed to high temperatures, this grade of stainless steel like most austenitic grades will also maintain its strength and toughness at sub-zero temperatures, making this an excellent choice for various applications ranging from oil refinery equipment to automotive exhaust systems. This heat resistant grade of stainless steel has a maximum dry air service temperature of 850ºC.
Stainless Steel 321H
Stainless Steel 321H is the higher-carbon modification of stainless steel 321. In addition, 321H is stabilized by an addition of niobium to resist intergranular corrosion. It is also able to withstand higher temperatures than type 321, due to its elevated carbon levels. While 321H displays the same welding and forming characteristics of type 321, the metal cannot be hardened by heat treatment. It is utilized in situations where type 321 cannot withstand the high temperatures, typically those exceeding 1000° F. Type 321H displays better resistance against creep than both 321 and 304 stainless steels.
321H also shows resistance against acid corrosion in a variety of environments. Lower temperatures provide better resistance, but the metal is able to withstand up to a 10% acid solution, that has been diluted, at elevated temperatures. However, the metal shows very little resistance against chlorine or sulfuric solutions at any given temperature.
321 Stainless Steel is a type of austenitic stainless steel that contains titanium as a stabilizing element. This steel is known for its excellent resistance to intergranular corrosion, especially in high-temperature environments. It is a popular choice for applications that require high strength and resistance to oxidation and deformation at elevated temperatures. This type of steel is used in a wide range of industries, including aerospace, chemical processing, automotive, and power generation. Its chemical composition includes chromium, nickel, and titanium, which make it highly durable and resistant to rust and stains.
Type 321 is a standard austenitic 18/8 chromium nickel alloy with the addition of Titanium making it an excellent choice in elevated temperature environments.
The titanium stabilises the material removing its susceptibility to the effects of intergranular corrosion. 321 is therefore the stainless steel material of choice for applications in working environments up to 900° C.
A drawback of Type 321 is that the titanium does not transfer well across a high temperature arc, so it is not recommended as a welding consumable
Alloy 321 (UNS S32100) is a titanium stabilized austenitic stainless steel 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 alloy 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.Alloy 321H (UNS S32109) 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 1000°F (537°C). In most instances, the carbon content of the plate enables dual certification.Alloy 321 cannot be hardened by heat treatment, only by cold working.It can be easily welded and processed by standard shop fabrication practices.
Applications of 321
- Useful in the chromium carbide precipitation range (800-1500°F, 427-815°C)
- Aircraft exhaust stacks
- Manifolds
- Chemical processing equipment
- Welded equipment
- Jet engine parts
- Heat Exchangers
- Expansion joints
321 Stainless product forms
- Sheet
- Plate
- Bar
- Pipe & Tube
- Flanges
- Fittings
- Elbows, tees, stub-ends, returns, caps, crosses, reducers, pipe nipples. وغیرہ.
- Weld Wire (AWS Classifications: ER347, ER321 and E347, E321)
Chemical Properties
| % | Cr | Ni | C | Si | Mn | P | S | N | Ti | Fe |
|---|---|---|---|---|---|---|---|---|---|---|
| 321 | min:17.0 max:19.0 | min: 9.0 max:12.0 | max:0.08 | max:0.75 | max:2.0 | max:0.045 | max:0.03 | max:0.10 | min:5*(C+N) max:0.70 | Balance |
| 321H | min:17.0 max:19.0 | min: 9.0 max:12.0 | min:0.04 max:0.10 | min:18.0 max:20.0 | max:2.0 | max:0.045 | max:0.03 | max:0.10 | min:5*(C+N) max:0.70 | Balance |
Equivalent to Grade 321
1.4541, Grade 321, Alloy 321, AISI 321, TYPE 321, UNS S32100, X6CrNiTi18-10, ASTM A240, 321H, 321 Stainless, T.321, SS321, 321SS, 321
| EU EN | USA – | Germany DIN,WNr | Japan JIS | France AFNOR | England BS | Italy UNI | China GB | Sweden SS | Poland PN | Czechia CSN | Finland SFS | Austria ONORM | Russia GOST |
| X6CrNiTi18-10 (1.4541) | 321 | X10CrNiTi18-9X6CrNiTi18-10 | SUS321 | Z6CNT18-10 | 321S31 | X6CrNiTi18-11 | 0Cr18Ni10Ti1Cr18Ni11TiH0Cr20Ni10Ti | 2337 | 0H18N10T1H18N9T | 1724717248 | 731 | X6CrNiTi18-10S | 08KH18N10T08KH18N12T12KH18N10T |
European equivalent grade for Austenitic stainless steel 321 ( AISI, ASTM, UNS): X6CrNiTi18-10 (1.4541)
Chemical composition and properties of european equivalents (EN) for 321 (USA, AISI, ASTM, UNS):
Heat-treatment Option
1 +A: Annealed (full/soft/spheroidizing)
2 +N: Normalized
3 +NT: Normalized and tempered
4 +QT: Quenched and tempered (water/oil)
5 +AT: Solution annealed/+AT annealing at 1020 – 1120℃ with cooling in water or air
6 +P: Precipitation hardened
Mechanical Properties
Average Elevated Temperature Tensile Properties
| Temperature, °F | Ultimate Tensile Strength, ksi | .2% Yield Strength, ksi |
|---|---|---|
| 68 | 93.3 | 36.5 |
| 400 | 73.6 | 36.6 |
| 800 | 69.5 | 29.7 |
| 1000 | 63.5 | 27.4 |
| 1200 | 52.3 | 24.5 |
| 1350 | 39.3 | 22.8 |
| 1500 | 26.4 | 18.6 |
Physical Properties
Typical physical properties for annealed grade 321 stainless sheets of steel are given in table 3.
Table 3. Physical properties of 321-grade stainless steel in the annealed condition
| Grade | Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (μm/m/°C) | Thermal Conductivity (W/m.K) | Specific Heat 0-100 °C (J/kg.K) | Electrical Resistivity (nΩ.m) | |||
| 0-100 °C | 0-315 °C | 0-538 °C | at 100 °C | at 500 °C | |||||
| 321 | 8027 | 193 | 16.6 | 17.2 | 18.6 | 16.1 | 22.2 | 500 | 720 |