AWS WHC-4.04:2010

Tool and Die Steels
Scope : Tool steels are high-quality ferrous metals used to make industrial tools, dies, cutting and forming tools, and other tools used in highly demanding service conditions. These steels are specially designed to accommodate the specific mechanical properties required for particular applications. The processes used by manufacturers to produce tool steels enable them to deliver clean, homogeneous material made according to precise requirements for chemical composition and microstructure. The cost of precise production requirements and rigid quality control is justified by the high cost of constructing intricate tools, dies, and molds and the potential downtime associated with premature tool failure. Preserving the unique as-manufactured properties of these steels is a factor that always must be taken into consideration before welding. Because of the carbon and alloy content in tool steels and the heat treatment necessary to obtain the required mechanical properties, welding must be performed by highly skilled technicians using accepted methods and process controls. The welding process greatly affects the workpiece in the heat-affected zone (HAZ). Therefore, welders must have a good working knowledge of heattreating processes as well as the manipulative skills required for the welding operations.1, 2 This chapter discusses the classifications, metallurgy, and weldability of tool steels and the processes involved with welding them. Information on repair welding procedures for tool steels is coordinated with the order in which the tasks should be performed, and is supplemented by several detailed descriptions in the section on applications.