Stainless Steel 321/321H

Products Description

Alloy 321 (UNS S32100) is a stabilized stainless steel plate that offers excellent resistance to intergranular corrosion when exposed to temperatures in the chromium carbide precipitation range of 800 to 1500°F (427 to 816°C). This is its main advantage over other stainless steel grades.The resistance to intergranular corrosion is achieved by the addition of titanium, which stabilizes the alloy and prevents the formation of chromium carbides at grain boundaries. This property makes Alloy 321 particularly suitable for applications where exposure to high temperatures is involved, as it maintains its corrosion resistance and structural integrity even in harsh conditions.

In addition to its corrosion resistance, Alloy 321 stainless steel plate also offers good mechanical properties, making it advantageous for high-temperature service. It exhibits higher creep and stress rupture properties compared to Alloy 304 and Alloy 304L. This makes it a preferred choice in situations where sensitization and intergranular corrosion are concerns, as Alloy 321 provides better performance in these areas.

General Properties

Alloy 321 (UNS S32100) is titanium stabilized austenitic stainless steel plate 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) stainless steel plate 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.

Alloy 321 stainless steel plate cannot be hardened by heat treatment, only by cold working. It can be easily welded and processed by standard shop fabrication practices.

Corrosion Resistance

 Alloy 321 stainless steel plate exhibits good general corrosion resistance that is comparable to Alloy 304 stainless steel. It was specifically developed for use in the chromium carbide precipitation range of 1800 – 1500°F (427 – 816°C), where un-stabilized alloys like Alloy 304 are susceptible to intergranular attack.Alloy 321 has good resistance to corrosion in most diluted organic acids at moderate temperatures and in pure phosphoric acid at lower temperatures. It can also withstand up to 10% diluted solutions at elevated temperatures. The alloy is resistant to polythionic acid stress corrosion cracking in hydrocarbon service. Additionally, it can be used in chloride or fluoride-free caustic solutions at moderate temperatures.

However, Alloy 321 stainless steel plate does not perform well in chloride solutions, even in small concentrations. It is also not recommended for use in sulfuric acid service. In these environments, other stainless steel grades with higher corrosion resistance, such as Alloy 316 or Alloy 317, may be more suitable.

Chemical Analysis

Weight % (all values are maximum unless a range is otherwise indicated)

Mechanical Properties

Typical Values at 68°F (20°C)