A short demonstration at BCIT's open house on riveting together steel together. It was a main type of connection for steel structures until the invention and adoption of the bolt. A lot of bridges you see, are still riveted together. Next time you are about, take a look around you.
The process begins heating up the pin. After the pin was cherry hot, they would literally through the red hot pin to another Ironworker whom would then place the pin a the hole and another two Ironworkers would then come behind (all will still cherry red) and use pneumatic hammers to form the "head' of the rivet. As the pin cooled, the steel shrinks, compressing the joint, thus holding it together.