Search Results for working

This chapter discusses the effects of hot working on the structure and properties of steel. It explains how working steels at high temperatures promotes diffusion, which helps close cavities and pores, and how it changes the shape and distribution of segregates, offsetting their effect. It describes the effect of hot working on nonmetallic inclusions and the many properties influenced by them. It discusses the recrystallization mechanism by which hot working produces microstructural changes and explains how to control it by adjusting temperature, degree of reduction, and cooling rates. It describes special cases of segregation, including banding and why it occurs, and the application of closed die forging. The chapter also presents several examples of hot working defects, including forging laps, cracks, and overheated or burned steel.

With cold work, mechanical strength (measured either by yield strength or ultimate tensile strength) increases and ductility (measured by elongation, reduction of area, or fracture toughness) normally decreases. This chapter discusses the mechanisms that produce these changes and the factors that influence them. It explains how cold working increases dislocation density and how that affects the stress-strain characteristics of steel, particularly the onset of deformation. It describes the effects of deformation on ferrite, austenite, cementite, and pearlite, and how to optimize their microstructure for various applications through controlled deformation. It also provides information on subcritical annealing, the examination and control of texture, the use of optical microscopy to monitor the effects of recrystallization, and the effect of cold working on threaded fasteners, nails, and filaments used to manufacture cords.

Most integrated titanium mills have primary working equipment designed specifically for titanium. This chapter describes the forging, rolling, and extruding equipment used to produce titanium mill products and sheds light on the corresponding process, structure, property relationships.

This chapter discusses the equipment and processes used to convert titanium billet and bar into useful shapes or more refined product forms. These secondary working operations include open-die, closed-die, hot-die and isothermal forging as well as ring rolling and extruding. The chapter describes each method in detail and how it affects the microstructure and mechanical properties of various titanium alloys. It also discusses the propensity of titanium to react with oxygen and hydrogen when heated and explains how to mitigate the effects.