Combination of aluminum and stainless steel
04-20-2021, 12:13 PM,
 davehetfield Newbie Posts: 1 Threads: 1 Joined: Apr 2021 Reputation: 0
Combination of aluminum and stainless steel
Hi everyone, after reading quite a bit about the thermal expansion of different materials, I still have some questions. Aluminum and stainless steel have a very different CTE, aluminum almost twice as much. How are they fused together and maintain their bond through heating and cooling cycles?
 Vadim Verlotski SuperMember Posts: 205 Threads: 0 Joined: Sep 2014 Reputation: 13
RE: Combination of aluminum and stainless steel
The stresses that arise in the junction of two metals depend not only on the difference in their thermal expansion coefficients. If we write down Hooke's law for these stresses, then it will look like this:
σ1 = E1ΔTΔα, where σ1 is the stress in one of the layers, E1 is the elastic modulus of this layer, ΔT is the temperature difference, Δα is the difference in the coefficients of linear thermal expansion.
Since the modulus of elasticity of aluminum is relatively small, and the softening temperature is low (there simply cannot be a large ΔT due to the transition of the material into a plastic state), the resulting stresses are also small. In addition, the difference in linear thermal coefficients between austhenic stainless steels (α = 17-18 x10-6K-1) and aluminum alloys (α = 20-23 x 10-6K-1) is not at all that significant.