About Stainless Steel 321/321H
What is 321/321H Stainless Steel?
- Stainless Steel 321 is a basic austenitic 18/8 steel (Grade 304) blend of chromium and nickel is stabilised by Titanium (321) addition. SS 321 is used because they are not sensitive to intergranular corrosion after heating within the carbide precipitation range of 425-850°C.
- Stainless Steel 321 is the grade of choice for applications in the temperature range of up to about 900°C, combining high strength, resistance to scaling, embrittlement and phase stability with resistance to subsequent aqueous corrosion. It is protected from temperatures ranging from 800 to 1500° F. The metal displays high strength and resistance to various forms of corrosions, including that from aqueous environments.
- Type 321 finds application in heavy welding components, along with dynamic environments that are subject to changes.
- Beyond this, stainless steel 321 has excellent forming characteristics, does not require annealing after being welded, and displays toughness in a range of temperatures. The metal shows strength even when exposed to cryogenic temperatures.
- Additionally, it is often chosen over Type 304 for its increased resistance to creep and rupture. Both metals may be susceptible to stress corrosion cracking. It is used to manufacture high quality carbon structural steel seamless steel tubes for hot rolling and cold drawing (rolling) of superheated steam pipe, boiling water pipe and locomotive boiler superheated steam pipe, large smoke pipe, small smoke pipe and arch brick.
- SS 321H is a modification of SS 321 with a higher carbon content, to provide improved high temperature strength. 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. Given their similar composition and characteristics, it is possible for stainless steels 321 and 321H to become dually certified.
What is the Difference Between 321 Stainless Steel and Other Grades?
The main variant of 321 is 321H which contains a higher quantity of carbon. 321 may contain up to 0.08% while 321H must contain between 0.04% and 0.08% carbon. The higher quantity of carbon confers greater strength at elevated temperatures. It is often chosen over Type 304 for its increased resistance to creep and rupture. 321 stainless steel is basically from 304 stainless steel. They differ by a very very small addition of Titanium. The real difference is their carbon content. The higher the carbon content the greater the yield strength. 321 stainless steel has advantages in high temperature environment due to its excellent mechanical properties. Compared with 304 alloy, 321 stainless steel has better ductility and resistance to stress fracture. In addition, 304L can also be used for anti-sensitization and intergranular corrosion.
Difference between 321 and other grades:
|Type 304||The most common of austenitic grades, containing approximately 18% chromium and 8% nickel. It is used for chemical processing equipment, for food, dairy, and beverage industries, for heat exchangers, and for the milder chemicals.|
|Type 316||Contains 16% to 18% chromium and 11% to 14% nickel. It also has molybdenum added to the nickel and chrome of the 304. The molybdenum is used to control pit type attack. Type 316 is used in chemical processing, the pulp and paper industry, for food and beverage processing and dispensing and in the more corrosive environments. The molybdenum must be a minimum of 2%.|
|Type 317||Contains a higher percentage of molybdenum than 316 for highly corrosive environments. It must have a minimum of 3% “moly”. It is often used in stacks which contain scrubbers.|
|Type 317L||Restricts maximum carbon content to 0.030% max. and silicon to 0.75% max. for extra corrosion resistance.|
|Type 317LM||Requires molybdenum content of 4.00% min.|
|Type 317LMN||Requires molybdenum content of 4.00% min. and nitrogen of .15% min.|
|These types have been developed for corrosive resistance for repeated intermittent exposure to temperature above 800 degrees F. Type 321 is made by the addition of titanium and Type 347 is made by the addition of tantalum/columbium. These grades are primarily used in the aircraft industry.|
Applications of Stainless Steel 321/321H
- For construction parts which should be resistant to scaling up to about 850°C and extensively inured to the effect of sulphurous gases. Inclination to carbonisation in reduced gases is very low.
- Expansion joints
- Chemical and Petrochemical processing
- Pharmaceutical production
- Waste treatment including thermal oxidizers
- Equipment and storage units for Food processing
- Aerospace Applications– piston engine manifolds
- Food Processing – equipment and storage
- Petroleum Refining – polythionic acid service
- Exhaust Systems
- Heat Exchangers
- Furnace Parts
- Chimney and Stack Liners
- Storage Tanks
Properties, Limitations and Processing Characteristics of Stainless Steel 321/321H
- Oxidation resistant to 1600°F
- Stabilized against weld heat affected zone (HAZ) intergranular corrosion
- Resists polythionic acid stress corrosion cracking
- Excellent resistance oxidation to 1500°F (816°C)
- Good low temperature toughness
- Comparable corrosion resistance and machinability to Type 304
- Readily welded by most standard processes
- It is malleable and ductile and has good weldability.
- Its austenitic structure allows it to be deep drawn without intermediate annealing. It is also unnecessary to anneal it following welding thin sections.
- It is generally recommended that Stainless 347 is used for welding rods and electrodes. (347 employs niobium and tantalum in preference to titanium)
- In its annealed state it is virtually non-magnetic even when cold worked, unlike 304 which can be significantly attracted to a magnet after cold working. This may make it more suitable in some applications.
- It also maintains its strength down to cryogenic temperatures.
- The key element that differentiates it from most other stainless steels is the inclusion of molybdenum, between 2% and 3%, which enhances its resistance corrosion in general and pitting corrosion in particular.
It is protected from temperatures ranging from 800 to 1500° F. The metal displays high strength and resistance to various forms of corrosions, including that from aqueous environments. Type 321 finds application in heavy welding components, along with dynamic environments that are subject to changes. The inclusion of molybdenum may have some adverse effects on its formability.
Processing / Welding
Alloy 321 stainless steel plate can be readily welded by most standard processes. A post weld heat treatment is not necessary. Standard welding processes for this steel grade are:
- MAG-Welding Solid Wire
- Arc Welding (E)
- Laser Bean Welding
In quenched condition the material can be slightly magnetizable. With increasing cold forming the magnetizability increases.
Equivalents of Stainless Steel 321/321H
Chemical, Mechanical & Physical Properties of Stainless Steel 321/321H
|NI||9.0 – 12.0||9.0 – 12.0|
|C||0.08 max||0.04 – 0.10|
|MN||2.0 max||2.0 max|
|P||0.045 max||0.045 max|
|S||0.030 max||0.030 max|
|SI||1.0 max||1.0 max|
|CR||17.0 – 19.0||17.0 – 19.0|
|TI||5(C+N) – 0.70 max||4(C+N) – 0.70|
|N||0.10 max||0.10 max|
|DENSITY||7.92 g/cm 3 / 0.286 lb/in 3|
|MELTING POINT||1398 – 1446 (°C) / 2550 – 2635 (°F)|
|ANNEALED||1040 – 1100 (°C) / 1900 – 2000 (°F)|
|Coefficient of Thermal Expansion (min/in)-°F||at 68 – 212°F||9.2|
|at 68 – 1832°F||20.5|
|Thermal Conductivity BTU/hr-ft-°F||at 200°F||9.3|
|Specific Heat BTU/lbm -°F||at 32 – 212°F||0.12|
|Modules of Elasticity (annealed)2-psi||in tension (E)||28 x 10 ^6|
|Grade||Tensile Strength||Yield Strength 0.2%||Elongation –||Hardness|
|Mpa (min.)||Offset Mpa (min.)||% in 50 mm (min.)||(Brinell) MAX|
|1% Elongation(1) for||Rupture(2) for|
|Temperature °C||1,000 h N/mm2||10,000 h N/mm2||1,000 h N/mm2||10,000 h N/mm2||100,000 h N/mm2|
Fabrication Data and Other Properties of 321/321H Stainless Steels
Alloy 321 stainless steel plate can be easily welded and processed by standard shop fabrication practices.
- The alloy is quite ductile and forms easily.
- The high sulfur content of Alloy 303 also has a detrimental impact on hot workability. If hot forming is required, once again, 304 should be considered as an alternate selection.
- The cold work hardening rate of 321 stainless steel plate makes it less machinable than 410 stainless steel, but similar to 304. The table below provides relevant machining data.
Heat Treatment and Resistance of Stainless Steel 321
321 resists oxidation up to 900oC in intermittent use and to 925oC in continuous use. It also avoids intergranular corrosion in the range 425 and 850oC.
- Annealing at 1800-2000 F (928-1093 C) air cool. This process will result in maximum ductility. For maximum corrosion resistance, see the note on settled anneal under corrosion.
- This alloy doesn’t harden by heat treating. High properties may only be obtained through cold reduction.
Corrosion Resistance of Stainless Steel 321
- Exhibits good general corrosion resistance that is comparable to 304.
- Developed for use in the chromium carbide precipitation range of 1800 – 1500°F (427 – 816°C) .
- Can be used in most diluted organic acids at moderate temperatures .
- Can be used in pure phosphoric acid at lower temperatures.
- Can be used in up to 10% diluted solutions at elevated temperatures.
- Resists polythionic acid stress corrosion cracking in hydrocarbon service.
- Utilized in chloride or fluoride free caustic solutions at moderate temperatures.
- Does not perform well in chloride solutions, even in small concentrations, or in sulfuric acid service.
Testing & Inspection of Stainless Steel 321/321H Materials
Testing (Destructive, Non Destructive)
|Positive Material Identification – PMI Testing||Hydrostatic Test|
|Chemical Analysis – Spectro Analysis||Hydrogen-Induced Cracking (HIC) Test|
|Mechanical Testing Such as Tensile, Elongation, Reduction of Area||Sulfide Stress Corrosion Cracking (SSC), NACE TM 0177|
|Micro Test||Radiography Test|
|Macro Test||Dye Penetrant Test (DP Test)|
|Hardness Test||Ultra Sonic Test (UT)|
|Pitting Resistance Test||Eddy Current Testing|
|Intergranular Corrosion (IGC) Test||Impact Test|
|Flaring Test||Bend Test|
- Our internal inspection reports would be provided for all the goods before shipment.
- Buyers or their associates are most welcome to visit us for personal inspect
- We regularly have inspections ongoing at our premises from internationally acclaimed Inspection Agencies such as TUV, BVIS, SGS, Llyods, DNV etc.
Prices for Stainless Steel 321/321H Materials
Prices for stainless steel 321/321H materials are directly co related to prices of the raw materials such as iron ore, metal scrap, chromium, nickel and various other alloying elements. The production cost of heat resistant stainless steel and nickel alloy plates is high as they contain high amount of nickel and chromium. Meanwhile, mild steel material is among the lowest cost steel available, followed by carbon steel, 400 series stainless steels, aluminium, alloy steel, and 300 series stainless steel. Special alloys such as titanium, Inconel, Monel and Hastelloy cost very high as the nickel, chromium and moly content is very high.
For special and discounted prices for various types of stainless steel 321/321H products, please feel free to contact us through email, phone or whatsapp.
We are also regularly publishing our price list for various steel products on our blog.
Documents Provided at the time of Domestic Sales or Export of Stainless Steel 321/321H Products
|Certificate of Origin||Raw Material Test Reports|
|Commercial Invoice||Heat Treatment Charts|
|Packing List||Quality Assurance Plan (QAP)|
|Fumigation Certificates||NABL approved Laboratory Test Reports|
|Letter of Gurantee||Material Test Certificates|
|ROHS Certificate||Certificate of Compliance/Conformity|
Price Basis for Stainless Steel 321/321H Materials
We can offer any of the following price basis depending on your requirement:
- FOR Site in India
- FOB Nhava Sheva
- CFR, CIF, CPT your destination port
- Door to Door Delivery Duty Paid as well as Duty Unpaid
Delivery Time of Stainless Steel 321/321H Materials
- If the items are available in stock, we take 2 days from the date of receipt of advance payment to clear the shipment and send it to port.
- And in-case the items are not availabe in stock, the time taken for manufacturing depends on the size, quantity and grade.
- However we can claim the fact that we can compete with anyone in India on Delivery time and most of the time our production time is the least.
- We have tied up with strong logistic partners in India which can undertake any type of shipping activities and make sure that there is no delay in shipment.
Marking & Packing of Stainless Steel 321/321H Materials
- All our products will have complete marking details which are co-related to the test certificates we supply.
- In case of orders for cut piece of Pipes, Sheets or Round Bars, the marking is transferred from the product from which it is cut. In such cases we provide Letter confirming the marking transfer and picture of the product from which it is cut.
- All goods are packed in wooden cases or pallets.