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Materials
Published in Ansel C. Ugural, Youngjin Chung, Errol A. Ugural, Mechanical Engineering Design, 2020
Ansel C. Ugural, Youngjin Chung, Errol A. Ugural
Hot working reduces the strain hardening of a material but avoids the ductility and toughness loss attributed to cold working. However, hot-rolled metals tend to have greater ductility, lower strength, and a poorer surface finish than cold-worked metals of the identical alloy. Examples of hot-working processes are rolling, forging, hot extrusion, and hot pressing, where the metal is heated sufficiently to make it plastic and easily worked. Forging is an automation of blacksmithing. It uses a series of hammer dies shaped to gradually form the hot metal into the final configuration. Practically any metal can be forged. Extrusion is used mainly for nonferrous metals and it typically uses steel dies.
Mechanical deformation of metals
Published in William Bolton, R.A. Higgins, Materials for Engineers and Technicians, 2020
A hot-working process is one which is carried out at a temperature well above the recrystallisation temperature of the metal or alloy. At such a temperature, recrystallisation will take place simultaneously with deformation and so keep pace with the actual working process (Figure 6.10). For this reason, the metal will not work-harden and can be quickly and continuously reduced to its required shape, with the minimum of expended energy. Not only is the metal naturally more malleable at a high temperature, but it remains soft, because it is recrystallising continuously during the working process.
Engineering Materials
Published in Leo Alting, Geoffrey Boothroyd, Manufacturing Engineering Processes, 2020
Leo Alting, Geoffrey Boothroyd
The term cold working refers to deformations carried out at temperatures below the recrystallization temperature, and the term hot working refers to deformations carried out at temperatures above the recrystallization temperature. Some metals recrystallize at room temperature (lead, tin, and zinc), which means that these metals are normally hot-worked. Strain hardening induced only in the surface layers of the component will often increase its fatigue strength as well as its hardness.
Novel robot arm design and implementation for hot forging press automation
Published in International Journal of Production Research, 2019
Chu A. My, Chi Hieu Le, Michael Packianather, Erik L.J. Bohez
Hydraulic hot forging press is the process of shaping a hot workpiece that is placed in a die by applying hydraulic pressure. This type of forging is usually done in a forging press machine that applies gradual pressure on the forging die. A manufacturing cell of hot forging press usually consists of two main components: a heating furnace and a forging press machine. The hot forging press process includes two main steps: the workpiece heating and the workpiece forging.
Accelerating the precipitation kinetics of nano-sized T1 and S’ phases in Al-Cu-Li alloys by hot-deformation and creep-aging
Published in Philosophical Magazine, 2023
Xinghai Yang, Junsheng Wang, Chengpeng Xue, Shuo Wang, Guangyuan Tian, Xingxing Li, Yuxuan Zhang, Xiaoxue Chang, Xiaoguang Liu
Plastic deformation in polycrystalline metallic materials is of fundamental importance in linking deformation micro-mechanisms and mechanical performance. Hot working is generally considered an effective method to improve the mechanical properties of metallic materials due to the refinement of the original microstructure. In the hot extrusion process, different extrusion ratios will produce not only various grain sizes but also precursors for nucleation since these precursors are completely facilitated by dislocation motions [22]. Moreover, due to the high stacking fault energy, dynamic recovery is the main softening mechanism in the hot deformation of aluminum alloys [23]. This process is also controlled by the interactions of the internal dislocations during the hot deformation. At present, the studies on the effects of hot deformation mainly focused on the grain (phase) internal structure/ interface [24], crystal plasticity [25], and dynamic recrystallization [26], which profoundly revealed the underlying mechanisms of the deformation process on material microstructure and damage behaviour. For example, more recent crystal plasticity investigations have emphasised the role of local strain energy in more accurately correlating grain boundary (GB)-induced heterogeneous deformation with initial damage event [27, 28]. In a recent study, Tang et al. [29] developed the multiple static softening mechanisms following multi-stage hot deformation of Al-Zn-Mg-Cu alloys by an integrated physically based model. They found that the complex precipitation behaviours have a considerable influence on recovery, recrystallization, and coupled static softening process. While the solid solution atoms remaining in the matrix contributed to grain boundaries mobility and then slow the recrystallization process. As described earlier, the creep aging combining both the aging treatment and forming process has drawn much researchers’ attention in recent years for the age-hardening Al-Cu-Li alloys. Creep deformation in alloys is generally induced by dislocation generation, motion, and annihilation. Basirat et al. [30] developed a micromechanical model for the creep deformation of the P91 steel. The dislocation evolution was modelled by considering dislocation generation and annihilation. In addition to dislocation motion, the significant factors of precipitate coarsening, and solid solution depletion during creep were also considered by including continuum damage terms in Orowan's equation.