308A Metal Types and Properties 5

Question 1

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

Accepted Answer

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

Answer

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.

Question 2

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

Accepted Answer

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

Answer

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.

Question 3

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

Accepted Answer

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

Answer

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.

Question 4

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

Accepted 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

Answer

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.

Question 5

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

Accepted Answer

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

Answer

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.

Red Seal Sheet Metal 308A Practice Test

Red Seal Sheet Metal 308A Practice Test

308A Metal Types and Properties 5