Metal Types and Properties Flashcards

What is the primary reason for specifying a particular 'temper' of aluminum sheet for a sheet metal project?

Answer: To ensure the aluminum has the correct combination of strength and formability for the intended application

Aluminum temper designations (O, H, T series) define the material's hardness, strength, and formability. Softer tempers (O, H12) are easier to form but weaker; harder tempers (H16, H18) are stronger but harder to form.

What does the designation '3003-H14' mean for aluminum sheet?

Answer: Alloy 3003, half-hard temper — a general-purpose alloy that has been strain-hardened to half the maximum hardness

3003 is the alloy designation (aluminum-manganese alloy, general purpose). H14 indicates it is strain-hardened to half-hard temper (H1=strain hardened only, 4=half hard). This is a common specification for HVAC and general sheet metal.

What is 'lead-coated copper' and what is it used for?

Answer: Copper sheet coated with lead to provide enhanced corrosion resistance and a uniform grey patina for architectural use

Lead-coated copper has a thin lead coating that provides enhanced corrosion resistance and weathers to a uniform grey colour instead of copper's green patina. It is used for architectural roofing and flashing applications.

What is the coefficient of thermal expansion and why is it important for sheet metal installations?

Answer: It indicates how much a metal expands or contracts with temperature change, which must be accommodated in design to prevent buckling or joint failure

The coefficient of thermal expansion defines how much a material changes length per degree of temperature change. Sheet metal installations must include expansion joints or slip connections to accommodate this movement.

What is the purpose of a 'mill test report' (MTR) for sheet metal materials?

Answer: To certify the chemical composition, mechanical properties, and specifications of the metal as manufactured

A mill test report (MTR or mill cert) is an official document from the manufacturer certifying the exact chemical composition, mechanical properties, and compliance with specified standards for a specific batch of material.

What is the difference between hot-rolled and cold-rolled steel sheet?

Answer: Hot-rolled is formed at high temperature with a rougher finish; cold-rolled is further processed at room temperature with tighter tolerances and smoother finish

Hot-rolled steel is formed above the recrystallization temperature, resulting in a scaled, rougher surface. Cold-rolled steel is further processed at room temperature, producing a smoother surface, tighter thickness tolerances, and increased hardness.