Do you know " How to evaluate workability of a material"

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From "Handbook of workability and process control"

Workability refers to the relative ease with which a metal can be shaped through plastic deformation. In this chapter, consideration is restricted to the shaping of materials by such bulk deformation processes as forging, extrusion, and rolling. The evaluation of workability of a material involves both the measurement of the resistance to deformation (strength) and determination of the extent of possible plastic deformation before fracture (ductility). Therefore, a complete description of the workability of a material is specified by its flow stress dependence on processing variables (for example, strain, strain rate, preheat temperature, and die temperature), its failure behavior, and the metallurgical transformations that characterize the alloy system to which it belongs.
However, the major emphasis in workability is on measurement and prediction of the limits of deformation before fracture. The emphasis in this chapter is on understanding the factors that determine the extent of deformation a metal can withstand before cracking or fracture occurs. It is important, however, to allow for a more general definition in which workability is defined as the degree of deformation that can be achieved in a particular metalworking process without creating an undesirable condition. Generally, the undesirable condition is cracking or fracture, but it may be another condition, such as poor surface finish, buckling, or the formation of laps, which are defects created when metal folds over itself during forging. In addition, in the most general definition of workability, the creation by deformation of a metallurgical structure that results in unsatisfactory mechanical properties, such as poor fracture toughness or fatigue resistance, can be considered to be a limit on workability.
Generally, workability depends on the local conditions of stress, strain, strain rate, and temperature in combination with material factors, such as the resistance of a metal to ductile fracture. In addition to a review of the many process variables that influence the degree of workability, the mathematical relationships that describe the occurrence of room-temperature ductile fracture under workability conditions are summarized in this chapter. The most common testing techniques for workability prediction are discussed in Chapter 4, “bulk workability testing” in this handbook. Much greater detail on these tests and on workability tests specific to a particular bulk forming process, such as forging, are given in subsequent chapters of this handbook.

hotpie

已经在别的帖子加分
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bluevincent

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