Upsetting is a forging process that makes for a thicker wall on the tube ends. The tube ends are heated to a near liquid state. The heated end is then placed in the upsetter machine and held in a clamp. The machine is engaged and it strikes the end of the tube with so much force that the metal to flows backwards a few inches. The exact new wall thickness and the location of this extra metal is set depending on which die and punch are placed in the upsetter.
Tempering is most often performed on steel that has been heated above its upper critical (A3) temperature and then quickly cooled, in a process called quenching, using methods such as immersing the hot steel in water, oil, or forced-air.
