To continue my post from above, let's look at physics and chemistry of the metals commonly used. Below is the heat transfer rate of those metals. The higher the metal, the faster they lose aka dissipate heat. This assumes the metal at the same mass as one another.

Copper – 401
Aluminum – 273
Brass – 109
Stainless Steel – 16

So what this means is that stainless steel is the SLOWEST to lose its heat. In other words, it retains heat in itself.


Now, the flip side of this is that aluminum will heat up a tad quicker from a cold start than stainless steel, assuming the same mass and same heating intensity. However, as soon as the heat source stops or reduced, the temperature of aluminum will drop almost instantly. Steel or stainless steel however will stay closer to the temperature it was heated too MUCH longer than aluminium. So in a braking action, as you as you let off that brake pedal, the aluminum is already cooling down by the time you get to the next braking section, steel however, isnt, at least not as quickly. This is why on race cars at night, say nascar at bristol, you'll see the rotors glowing red almost entirely around the track. Because they take forever to cool.

You can test this youself, all you need is some aluminum and steel rods that are the same mass, a blow torch, a digital laser thermometer and some safety equipment. Heat both pieces up to the exact same temp, then use a stop watch to see which drops faster. But I'll save you the time, it'll be the aluminum one.

Hope that makes sense, I'm not always very good at explaining things via type.