Type 18 SR® Stainless Steel (UNS S43035)

In Coil Form and Precision Processed Strip

18 SR is a titanium-stabilized ferritic stainless steel developed for elevated-temperature service. The addition of aluminum provides excellent resistance to oxidation and scaling, allowing the alloy to perform in dry air at temperatures up to 2000°F. Compared to common heat-resistant grades such as Types 409, 430, and 304 stainless steel, 18 SR offers superior high-temperature scaling resistance.

In addition to its heat-resistant properties, Type 18 SR provides corrosion resistance, formability, and weldability similar to Types 439 and 441 stainless steel. These characteristics make it a reliable choice for a wide range of industrial and thermal processing applications.

Designed for High-Temperature Service

Type 18 SR is engineered for environments where prolonged exposure to extreme heat can degrade conventional stainless steels. Its combination of oxidation resistance, thermal stability, and fabrication characteristics allows it to maintain performance in demanding high-temperature applications.

This combination of heat resistance, durability, and fabricability makes 18 SR a popular choice for thermal processing equipment, industrial heating systems, and exhaust applications.

Benefits of Type 18 SR

  • Excellent oxidation and scaling resistance
  • Designed for service temperatures up to 2000°F in dry air
  • Superior high-temperature scaling resistance compared to Types 409, 430, and 304
  • Good corrosion resistance
  • Good formability and weldability
  • Titanium-stabilized for improved high-temperature performance
  • Cost-effective alternative to higher-alloy heat-resistant materials in suitable applications

Common Applications for Type 18 SR

  • Industrial ovens
  • Furnace components
  • Heat exchangers
  • Thermal processing equipment
  • Automotive exhaust systems
  • Exhaust manifolds
  • Heat shields
  • Combustion system components
  • Flue liners
  • Industrial heating equipment
  • Commercial electrical resistors
  • Edge-wound resistor assemblies
  • Flat resistor banks
  • High-speed rail motors and braking systems

Why Choose Type 18 SR?

Type 18 SR is often selected when applications require long-term exposure to elevated temperatures and resistance to oxidation and scaling. Its ability to perform in temperatures up to 2000°F makes it well suited for thermal processing, combustion, and exhaust environments where standard stainless steels may experience accelerated degradation.

In commercial electrical resistor applications, Type 18 SR is used in both edge-wound and flat resistor bank designs because it can withstand sudden temperature increases approaching 2200°F. These resistor systems are commonly used to protect DC motors and are frequently found in high-speed rail motor and braking applications.

For manufacturers seeking a combination of heat resistance, fabrication ease, and long service life, Type 18 SR offers a dependable solution for demanding thermal environments.

Available Forms

Rolled Metal Products supplies Type 18 SR in coil, sheet, and precision processed strip forms. Material can be processed to customer requirements using our in-house slitting, oscillate winding, tempering/re-rolling, and edging capabilities.

As a preferred distributor of 18 SR, Rolled Metal Products stocks nine standard thicknesses to support a wide range of industrial, thermal processing, and electrical resistor applications. Available gauges, widths, tempers, and processing options vary based on inventory and application requirements.

Chemical Composition

Chemical composition (wt%) limits of 18 SR*

Element 18 SR
Carbon 0.015
Chromium 18.0
Manganese 0.30
Silicon 0.60
Aluminum 2.0
Titanium 0.25
* Maximum, unless range is indicated

Mechanical Properties

Typical room temperature mechanical properties for annealed product

Property 18 SR
Yield Strength, min. (ksi) 56
Tensile Strength, min. (ksi) 78
Elongation, min. (%) 30
Hardness, max. (Rb) 84
18 SR® is a registered trademark of AK Steel Corporation

Physical Properties

Physical properties for 18 SR stainless steel

Property 18 SR
Density, lb/in3 0.27
Modulus of Elasticity, psi 29 x 106
Coefficient of Thermal Expansion, 68-212˚F, /˚F 5.9 x 10-6
Thermal Conductivity, Btu/ft hr ˚F 13.2
Specific Heat, Btu/lb ˚F 0.11
Electrical Resistivity, Microohm-in 37.40-41.34

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Data are typical, are provided for informational purposes, and should not be construed as maximum or minimum values for specification or for final design, or for a particular use or application. The data may be revised anytime without notice. We make no representation or warranty as to its accuracy and assume no duty to update. Actual data on any particular product or material may vary from those shown herein.
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