Welded componants for machines. Materials weldability

This article looks at the problems posed by the use of welding on the various alloy grades offered by the two main categories of materials: steels and aluminium alloys.

After a brief review of the metallurgical problems posed by the application of thermal cycles to locally melt the steel, the author describes the methods used to study cooling transformations, which have led to the characterization of the behavior of steel grades during arc welding, and then presents the current codified approaches used to prevent cold cracking. By means of a functional classification of the various families of steels used in mechanical engineering, the article reviews the characteristics of steels that can be supplied in accordance with current normative documents, as well as their behavior during welding. The article also discusses the potentially brittle behavior of certain ferritic and martensitic grades, and describes simplified methods for preventing this mode of failure.

A similar approach is adopted for aluminum alloys, and selection criteria are examined for both categories. Tables summarizing the various standardized grades for steel and aluminum alloys can be found in the article "Welded mechanical parts – Grade characteristics" [BM 5 188] .