INTRODUCTION

The various metallurgical phenomena involved in welding—melting, freezing, diffusion, precipitation, solid-state transformations, thermal strains, and shrinkage stresses—can cause many practical concerns. These problems can be addressed by applying the appropriate metallurgical principles to the welding process. Welding metallurgy differs from conventional metallurgy in certain important respects. However, a broad knowledge of physical metallurgy is necessary in order to understand welding metallurgy. For this reason, the topic of physical metallurgy is addressed first in this chapter. This discussion is followed by an examination of the specifics of welding metallurgy.