What are the different grades of stainless steel strip metal stock available?

2025-11-10 08:03:53

Grades of Stainless steel strip Metal Stock: A Comprehensive Guide

stainless steel strip metal stock is widely used in various industries due to its corrosion resistance, durability, and versatility. Different grades of stainless steel offer unique properties, making them suitable for specific applications. This guide explores the most common grades of stainless steel strip metal stock, their compositions, properties, and typical uses.

1. Introduction to Stainless Steel Grades

Stainless steel is an alloy primarily composed of iron, chromium (at least 10.5%), and varying amounts of other elements such as nickel, molybdenum, manganese, and carbon. The addition of chromium forms a passive oxide layer that provides corrosion resistance.

Stainless steel grades are categorized into five main families:

1. Austenitic Stainless Steel

2. Ferritic Stainless Steel

3. Martensitic Stainless Steel

4. Duplex (Ferritic-Austenitic) Stainless Steel

5. Precipitation-Hardening Stainless Steel

Each family has distinct mechanical and chemical properties, making them suitable for different applications.

2. Austenitic Stainless Steel Strip Grades

Austenitic stainless steel is the most widely used type due to its excellent corrosion resistance, formability, and weldability. These grades are non-magnetic in the annealed condition and can be hardened only through cold working.

Common Austenitic Grades for Strip Metal Stock

A. 304 / 304L (UNS S30400 / S30403)

- Composition: 18% Cr, 8% Ni, low carbon (304L has ≤0.03% C)

- Properties:

- Excellent corrosion resistance

- Good formability and weldability

- Non-magnetic when annealed

- Applications:

- Kitchen equipment, food processing, chemical tanks, architectural trim

B. 316 / 316L (UNS S31600 / S31603)

- Composition: 16-18% Cr, 10-14% Ni, 2-3% Mo

- Properties:

- Superior corrosion resistance (especially against chlorides)

- Better high-temperature strength than 304

- Applications:

- Marine environments, pharmaceutical equipment, surgical instruments

C. 321 (UNS S32100)

- Composition: Similar to 304 but with titanium (Ti) addition

- Properties:

- Resists carbide precipitation (sensitization) during welding

- Good high-temperature strength

- Applications:

- Aerospace, exhaust systems, heat exchangers

D. 347 (UNS S34700)

- Composition: Similar to 304 but with niobium (Nb) and tantalum (Ta)

- Properties:

- Excellent intergranular corrosion resistance

- High-temperature stability

- Applications:

- Welded components, chemical processing equipment

3. Ferritic Stainless Steel Strip Grades

Ferritic stainless steels are magnetic, have good corrosion resistance, and are less expensive than austenitic grades due to their lower nickel content. However, they are less ductile and cannot be hardened by heat treatment.

Common Ferritic Grades for Strip Metal Stock

A. 430 (UNS S43000)

- Composition: 16-18% Cr, low carbon

- Properties:

- Good corrosion resistance (weaker than 304)

- Magnetic and less formable than austenitic grades

- Applications:

- Automotive trim, kitchen appliances, decorative applications

B. 409 (UNS S40900)

- Composition: 10.5-11.75% Cr, titanium-stabilized

- Properties:

- Lower cost, moderate corrosion resistance

- Good weldability

- Applications:

- Automotive exhaust systems, heat exchangers

C. 439 (UNS S43035)

- Composition: 17-19% Cr, titanium-stabilized

- Properties:

- Better corrosion resistance than 430

- Improved weldability

- Applications:

- Water heaters, exhaust components

4. Martensitic Stainless Steel Strip Grades

Martensitic stainless steels are magnetic, hardenable by heat treatment, and offer moderate corrosion resistance. They are commonly used where high strength and wear resistance are required.

Common Martensitic Grades for Strip Metal Stock

A. 410 (UNS S41000)

- Composition: 11.5-13.5% Cr, low carbon

- Properties:

- Can be hardened by heat treatment

- Moderate corrosion resistance

- Applications:

- Cutlery, fasteners, turbine blades

B. 420 (UNS S42000)

- Composition: 12-14% Cr, higher carbon than 410

- Properties:

- Higher hardness and wear resistance

- Lower toughness than austenitic grades

- Applications:

- Surgical instruments, knife blades

C. 440C (UNS S44004)

- Composition: 16-18% Cr, high carbon (0.95-1.20%)

- Properties:

- Exceptional hardness and wear resistance

- Lower corrosion resistance than austenitic grades

- Applications:

- Bearings, high-end cutlery

5. Duplex Stainless Steel Strip Grades

Duplex stainless steels combine austenitic and ferritic structures, offering high strength and excellent corrosion resistance, particularly against stress corrosion cracking.

Common Duplex Grades for Strip Metal Stock

A. 2205 (UNS S32205)

- Composition: 22% Cr, 5% Ni, 3% Mo, 0.15% N

- Properties:

- High strength and toughness

- Excellent resistance to chloride-induced stress corrosion

- Applications:

- Chemical processing, oil & gas pipelines

B. 2507 (UNS S32750)

- Composition: 25% Cr, 7% Ni, 4% Mo, 0.27% N

- Properties:

- Superior pitting and crevice corrosion resistance

- Higher strength than 2205

- Applications:

- Desalination plants, marine environments

6. Precipitation-Hardening Stainless Steel Strip Grades

These grades can be hardened through heat treatment, offering a combination of high strength and corrosion resistance.

Common Precipitation-Hardening Grades for Strip Metal Stock

A. 17-4PH (UNS S17400)

- Composition: 15-17.5% Cr, 3-5% Ni, 3-5% Cu

- Properties:

- High strength after heat treatment

- Good corrosion resistance

- Applications:

- Aerospace components, nuclear reactors

B. 15-5PH (UNS S15500)

- Composition: Similar to 17-4PH but with lower carbon

- Properties:

- Better toughness and impact resistance

- Applications:

- High-stress aerospace and defense components

7. Conclusion

Selecting the right stainless steel strip grade depends on factors such as corrosion resistance, mechanical properties, weldability, and cost. Austenitic grades (304, 316) are ideal for general-purpose applications, while ferritic (430, 439) and martensitic (410, 420) grades are used where cost or hardness is a priority. Duplex (2205, 2507) and precipitation-hardening (17-4PH) grades are chosen for high-performance applications requiring strength and corrosion resistance.

Understanding these grades ensures optimal material selection for industrial, automotive, medical, and construction applications.