Stainless steel (SS) offers unlimited possibilities in sheet metal fabrication due to the many grades available today.
Whether you want stainless steel material for kitchenware, screw machining, or steam turbine blades – there are specific SS grades that can match your application requirements.
So, if you want to learn about the classification criteria, applications, or characteristics of various stainless steel grades – then, this is the right guide for you.
Table of Contents
Austenitic Stainless Steel Grades
Austenitic Stainless Steel Chemical Composition – Photo credits: Wikipedia
They are mainly the 300 series and 200 series.
Most SS grades in this category are known for:
Face-centered cubic structure
They have excellent resistance to corrosive conditions
Chromium composition ranges from 16 to 26%
Up to 35% nickel
Carbon content is low
Recommended for heat treatment
Non-magnetic properties
Suitable for cryogenic applications
Let’s look at austenitic SS grades:
Austenitic Stainless Steel Grade
Description
201
It has low nickel content and was developed to address the shortage of nickel during the 1950s.
The yield strength is better than 301
Resistance is lower compared to other austenitic SS grades
In most cases, it can substitute the 301 SS
Suitable for flatware, cooking utensils, door parts, washing machine, etc.
202
Has low nickel content
Low toughness
Low corrosion resistance
An affordable alternative that can substitute 304SS
Suitable for kitchenware, hose clamps kitchen sinks, etc.
205
Perfect for spin-forming applications
Good ductility and formability
It is common when making the stainless steel precipitation hardening grade
Possess good corrosion resistance
Ductile and soft when solution annealed condition
301
Good corrosion resistance
For cold working, it has a slightly high carbon content
Best for stretch forming in the annealed condition
Suitable for fasteners, car parts, and trailer body construction
It has a high work-hardening rate
301LN has low carbon content to improve ductility, with high nitrogen composition
301L is another variant of 301LN, except that the latter has a high nitrogen content
302
It is a general-purpose SS grade
302 and 304 share most properties; however, 302 has a higher carbon content
Restrictions in the application are due to the carbide precipitation formation
Suitable for spinning, wire forming, and stamping applications when making springs, cables, or washers
In 302HQ, there is 3% to 4% copper making a good wire alloy
303
Increased machinability
Suitable for parts requiring heavy machining such as gears, screws, bolts, nuts, etc.
303 is similar to 304 SS except for the extra sulfur to improve its machining properties
However, sulfur lowers corrosion resistance
There is the grade 303Se without sulfur but contains selenium. Consequently, it has better hot-forming and cold-forming properties
304
It is a low-carbon and economical stainless steel grade
Although the 304 is weldable, the grade is not resistant to seawater
It is common and a perfect choice for many applications today
Applications include piping systems, heat exchangers, home appliances, building structures, etc.
Also referred to as 18/8
Good welding and forming properties
Best for deep-drawn stainless steel parts such as sinks, or hollow-ware
304L
A 304 version but with low carbon composition
Suitable for heavy gauge fabrication since it does not require post-weld annealing operations
Low post-welding corrosion
304H grade has high carbon content making it a perfect choice for high-temperature applications
305
Suitable for blanking, spin forming, and deep drawing applications
It has low work hardening rate. This is contributed by the high nickel content in this SS grade.
Excellent corrosion resistance though may discolor or pit in high chloride or saltwater
Oxyacetylene welding is not suitable for 305 stainless steel grade
Applications may include cold-headed rivets, barrels, shells, etc.
308
It is a common filler material in 304 stainless steel grade welding
It is a high-alloy steel
20% chromium – As a result, this SS has exceptional resistance to any corrosive element or environment
Suitable for making pump parts, bolts, lever parts, etc.
309
The SS grade highly resists any possible oxidation even at high temperature
Resistance to deformation and creep
May experience intergranular corrosion after a long time of exposure
Resistant to scaling
Strength matches 304 stainless steel grade
Oxyacetylene welding is not suitable for 309 SS grade
Common applications include heat exchanger systems, boiler systems, fireboxes, furnace components, etc.
310
Resistant to high temperature and scaling
Highly resistant to oxidation
310S has a low carbon and excellent corrosion resistance in salty environments
Not suitable for regular liquid quenching due to the risk of thermal shock
Both 310 and 310s can be cold formed
Common applications include furnace systems, kilns, steam boilers, radiant tubes, heat exchanger systems, etc.
314
Resistant to scaling and high temperature
It is similar to 310S except for the extra silicon to enhance oxidation and carburization resistance properties
Suitable for making radiant tubes, furnace parts, heat treatment systems, etc.
316
Adding molybdenum increases corrosion resistance in seawater and acidic environments
After 304 SS, 316 is the next important austenitic stainless steel
Excellent resistance to pitting and crevice corrosion
Excellent welding properties and do not require post-weld annealing
Common applications include chemical tanks, machine components, medical equipment, etc.
316L
It shares the same properties as 316. However, it has low carbon thereby improving corrosion resistance after welding
316h has high carbon content making it suitable for extremely high-temperature applications
316Ti is a titanium-stabilized stainless steel grade. Stabilization help eliminate the possibility of losing excellent corrosion resistance properties in heat-affected zones
317
Better corrosion and creep resistance
Unlike the 316 with 2 to 3% molybdenum, 317 has more than 3% molybdenum
Tougher than 304 SS
317L has low carbon content than 317
Oxyacetylene not recommended
Suitable for the textile industry, chemical equipment, or pulping paper
321
Excellent performance in high-temperature applications
High titanium content
Excellent resistance to intergranular corrosion after heating
Excellent resistance to scaling
Perfect choice for applications with temperatures going above 900 °C
321H has higher carbon content, thereby improving strength in high-temperature applications
Not suitable for welding consumables hence you can choose 347 instead
If the performance requirement only requires resistance to intergranular corrosion, then 304L is a better alternative.
329
It is duplex austenitic stainless steel
Even at high temperatures, it is resistant to stress-crack and pitting
Exhibits improved machinability
Slightly difficult to weld
Best for centrifugal equipment
330
More nickel makes 330 SS resistant to oxidation even at high temperature
It is resistant to stress corrosion, thermal shock, or carburization
Specially designed for industrial applications at high temperatures such as heat treatment equipment, heat exchanges, gas turbines, etc.
GAW welding technique is highly recommended
High strength makes cold working difficult
347
Known for high creep-strength
Excellent intergranular corrosion resistance
A perfect choice for making jet engine components
It is a stabilized austenitic stainless steel with columbium and tantalum
348
Stabilized with columbium/tantalum
Excellent resistance to intergranular corrosion
Good choice for applications requiring intermittent heating
It is tougher than 304 SS grade
Avoid Oxyacetylene welding
Suitable for blanking, stamping, stamping, or drawing
It suitable for most nuclear applications
384
Has low tensile strength
Suitable for making bolts, screws
Best for forming wrought products
904L
Softer than 316L
Excellent resistance to crevice corrosion and pitting due to extra molybdenum
Processing 904L is difficult compared to 316L
904L is costly
Applications include heat exchanger systems, piping, bleaching systems, etc.
Ferritic Stainless Steel Chemical Composition – Photo credits: Wikipedia
Ferritic SS may be a better alternative in metal fabrication. However, austenitic stainless steels have better corrosion resistance than the Ferritic SS.
Although there are many Ferritic SS grades, the main characteristics are:
Low carbon content of about 2%
5% to 27% chromium content
Very little or no nickel content
Can be cold work hardened
Harding using heat treatment is not recommended
Cold working can increase the hardness
Resistant to temperature oxidation
Resistant to stress corrosion cracking
Fabrication properties tend to be poor which may require improvements
Some common grades include:
Ferritic Stainless Steel Grade
Description
405
It is a non-hardenable SS grade
Post-weld annealing improves the ductility
Don’t use oxyacetylene welding on this stainless steel grade
Common applications include partitions, steam nozzles, quenching boxes, etc.
Can be formed by drawing and spinning
429
Compared to 430 SS, 429 has better welding properties
It has good corrosion resistance
Applications include making household gadgets, internal decoration for architectural structures, mining equipment, bolts, nuts, automotive parts, etc.
430
Common applications are dishwashers, baskets, automotive trim, chimney liners, fasteners, etc.
Best for cosmetic application on both exterior and interior surfaces
Post-weld treatment is necessary to restore corrosion resistance
Corrosion resistance is almost the same as 304 and 304L
It does not work harden faster
Can resist nitric acid attack
There is the 430F, which is popular for free machining
434
It is simply the 430 SS grade but with molybdenum, which improves corrosion resistance
Excellent oxidation and heat resistance
436
Applications include automotive trim, forging wrought products
There is the 436L with better oxidation and corrosion resistance than the 409 SS
Polishing 436 results in an appearance similar to a chromium plate
442
Resistant to scaling and high temperature
Common applications include furnace components
A popular precipitation-hardening grade
It has high hardness
Generally, the strength is good
Excellent corrosion resistance properties
446
Suitable for intermittent use
Exhibit scaling and high-temperature resistance
It is non-heat treatable
Excellent resistance to corrosion and high-temperature oxidation
502
A perfect choice for petrochemical equipment
It has high strength with heat-resistant properties
As you can see, there are many stainless steel grades in the market. In fact, as technology advances, we may expect more grades for specialized applications.
Therefore, before starting any stainless steel fabrication process, ensure you choose the correct grade.
At TuoLian, we will help you choose the correct stainless steel material – contact us now.
