Choosing the right metal is a critical decision for engineers. The decision affects how easily a part can be fabricated, how long it will last in its environment, whether it meets safety or regulatory requirements, as well as the project’s cost. As a metal fabrication shop with extensive experience, we frequently assist engineers in evaluating material options to ensure the final product performs as intended while keeping costs under control. This guide provides general information on performance tradeoffs, common grades, and design considerations for various metals, helping engineers select the best material for their project.
Questions to Ask Before Choosing a Metal
Before selecting a material for fabrication, engineers should answer several key questions to avoid premature failures, corrosion issues, or unnecessary costs:
Will the metal be exposed to moisture, chemicals, or corrosive environments? For example, stainless steel resists corrosion well, but if chlorides are present (like saltwater), 316 stainless is needed over 304.
Will it be in contact with abrasive materials or surfaces? If the metal faces frequent wear (e.g., chutes, guards, or hoppers with granular flow), hardness and surface treatments should be evaluated to prevent rapid thinning or gouging.
Is the part used outdoors or indoors? Outdoor exposure demands corrosion-resistant metals, like aluminum, stainless steel, or galvanized steel, or protective coatings on mild steel.
Will it contact dissimilar metals? Galvanic corrosion can occur when metals like aluminum and steel are joined in the presence of moisture. Design solutions may require isolators or coatings to prevent degradation.
What fabrication processes are required? Consider if the metal must be formed into tight bends, welded extensively, or machined to tight tolerances. Not all metals handle forming or welding equally well, impacting design feasibility.
Are there aesthetic or hygiene requirements? Food processing applications require specific stainless finishes for cleanability. Architectural features may require painted, polished, or specialty metals for visual appeal.
Answering these questions ensures your metal fabrication shop can recommend the optimal material for durability, performance, and ease of fabrication.
Performance and Design Tradeoffs of Common Metals Used by Metal Fabrication Shops
Mild Steel: Strength at Low Cost
Our capabilities: 20 gauge to 1 inch
Common grades:
- ASTM A36 – General-purpose structural steel; welds easily and is widely available.
- SAE 1018 – Cold-rolled; offers better machinability and surface finish for precision parts.
Design considerations:
- Requires protective coating (paint or powder) to prevent rust.
- Thinner sections can distort under welding heat without proper fixturing.
- Machines cleanly with standard tooling.
Applications: Structural frames, brackets, supports, and fabricated components not exposed to moisture.
Stainless Steel: Corrosion Resistance and Cleanability
Our capabilities: 26 gauge to 1 inch
Common grades:
- 304 – General-purpose; good corrosion resistance and formability.
- 316 – Superior resistance to chlorides (marine and chemical environments).
Design considerations:
- Grade selection is critical based on the environment.
- Thermal expansion is higher than that of carbon steel; design allowances are needed in assemblies.
- Finish specifications (e.g., 2B, #4, mirror) affect cost and cleanability.
Applications: Food processing equipment, washdown areas, exterior architectural features.
Galvanized Steel: Affordable Corrosion Protection
Our Capabilities: 26 gauge to 10 gauge
Grades relate to coating thickness, such as G60 or G90 (zinc weight per square foot).
Design considerations:
- Welding burns off the zinc coating, requiring post-weld re-coating to maintain corrosion resistance.
- Tight bends can crack the coating; follow the supplier’s minimum bend radius guidelines.
- Surface prep is needed if painting over galvanized steel to ensure adhesion.
Applications: Ductwork, exterior enclosures, structural components exposed to weather.
Aluminum: Lightweight with Corrosion Resistance
Our Capabilities: 0.32 inch to 1 inch
Common grades:
- 5052 – High formability, decent weldability; marine applications.
- 6061 – Stronger, heat-treatable, good machinability; harder to form tight bends.
Design considerations:
- Weldability differs by grade; 6061 requires careful filler choice to avoid cracking.
- High thermal expansion can impact mixed-material assemblies.
- Galvanic corrosion risk when contacting steel or copper in wet environments; design isolators if needed.
Applications: Platforms, guarding, enclosures, where reduced weight improves ergonomics and installation.
Painted Metals: Aesthetic and Protective Finish
Our Capabilities: 26 gauge to 22 gauge
Base metal is typically galvanized or Galvalume with a factory-applied paint system.
Design considerations:
- Tight bends may crack paint coating, exposing metal to corrosion; follow minimum bend radius recommendations.
- Field touch-ups on cut edges or scratches are essential to maintain protection.
Applications: Architectural trim, flashing, and enclosure panels with color-matching requirements.
Specialty Metals: Copper, Bronze, Brass, and More
Our Capabilities: Custom ordered per project
Common uses:
Copper (C110, C122): Electrical conductivity, plumbing, architectural cladding.
Brass: Decorative fixtures, fittings requiring corrosion resistance and machinability.
Bronze: Bearings, marine fittings.
Design considerations:
- Significantly higher material cost; justify with required performance or aesthetics.
- Form well but require sharp tooling to avoid surface damage.
- Galvanic compatibility must be checked when joined with other metals.
Applications: Architectural details, electrical components, specialty mechanical fittings.
Contact Us for Your Metal Fabrication Needs
Ready to choose the right material for your next project? Contact us today to review your designs to help you get the best performance and value.