Medium carbon steel is an important engineering material used extensively where hardness, wear resistance and strength are required. A major consideration when welding medium carbon steels is the likelihood of formation of martensite in the heat affected zone (HAZ). This renders the weldment susceptible to cracking. Therefore, special precautions such as proper joint design and preparation; low hydrogen processes and consumables; and postweld heat treatment have to be taken when welding these steels to produce sound quality welds. This book discusses the result of a research conducted to investigate the effect of weld joint geometry and postweld heat treatment on the mechanical properties of weld in a medium carbon steel.