Welding Inspection & Metallurgy API ICP Self Study Notes

10.3.2 Thermal Conductivity
The thermal conductivity of a material is the rate at which heat is transmitted
through a material by conduction or thermal transmittance.
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In general, metals with high electrical conductivity also have high
thermal conductivity.
Materials with high thermal conductivity require higher heat inputs to
weld than those with lower thermal conductivity and may require a
pre-heat.
Steel is a poor conductor of heat as compared with aluminum or copper. As a
result it takes less heat to melt steel.
Aluminum is a good conductor of heat and has the ability to transfer heat
very efficiently. This ability of aluminum to transfer heat so efficiently also
makes it more difficult to weld with low temperature heat sources.