"Zillah bore Tubal-Cain; he was the forger of all instruments of bronze and iron."
Genesis 4:22
Metallurgy is one of the most ancient fields of technology and also one of the most important. The use of metals has been so essential to humankind that long periods of history—the Bronze Age and the Iron Age—have been named after the metals that were used most predominantly in those times.
Being able to join pieces of metal together has always been essential in making metal artifacts. The joining can be done in a number of different ways, including welding, brazing, and soldering. Metal items to be joined by welding must themselves be partly melted before the joining can take place.
Brazing or soldering—which are sometimes called "hard" and "soft" soldering respectively, with brazing carried out at a higher temperature—are processes whereby pieces of metal are joined together by the introduction of a metal melted into liquid form. This "filler" metal acts like glue in joining the pieces of metal together. The temperature required to melt the filler metal is lower than that required to melt the metals to be joined. This factor allows metal items to be joined together without themselves ever having to undergo whole or partial melting.
Brazing was discovered before either welding or soldering. It may have occurred as early as 4000 B.C.E., and samples of work where brazing was used to integrate pieces of metal have been dated to 2500 B.C.E. The techniques of brazing and soldering have been refined over thousands of years. They continue to be important today, having applications in a variety of metallurgical fields, most notably engineering and electronics.
