General Review 上产克大睾 SHEAMGHAI DUD TONO UHTVEREETTY Techniques of mechanical processing Modelling techniques address the t following design and manufacturing issues. o The design requirements are: Arriving at optimum processing conditions Controlling the microstructure in the component Designing optimum die shapes or perform geometry without resorting to shop floor trials >Obtaining the process limits for the design of control systems The manufacturing issues revolve around: The reduction of lead time in manufacturing Increasing the productivity without sacrificing the product quality Reducing the rejects to improve yield Ensuring the repeatability in manufacturing Institute of Forming Technology Equipment
General Review Institute of Forming Technology & Equipment Techniques of mechanical processing 7 Modelling techniques address the following design and manufacturing issues. The design requirements are: Arriving at optimum processing conditions Controlling the microstructure in the component Designing optimum die shapes or perform geometry without resorting to shop floor trials Obtaining the process limits for the design of control systems The manufacturing issues revolve around: The reduction of lead time in manufacturing Increasing the productivity without sacrificing the product quality Reducing the rejects to improve yield Ensuring the repeatability in manufacturing
General Review 上产克大睾 SHEAMGHAI DUD TONO UHTVEREETTY Workability Formability Workability refers to the relative ease with which a metal can be shaped through plastic deformation. This general term includes all other terms like forgeability, rollability,extrudability and formability (sheet metal working). A complete description of the workability of a material its flow stress dependence on processing variables(for example, strain,strain rate,preheat temperature and die temperature), stress state in the deformation zone,its failure behavior,and the metallurgical transformations that characterize the alloy system to which is belongs. Institute of Forming Technology Equipment 8
General Review Institute of Forming Technology & Equipment Workability & Formability 8 Workability refers to the relative ease with which a metal can be shaped through plastic deformation. This general term includes all other terms like forgeability, rollability, extrudability and formability (sheet metal working). A complete description of the workability of a material : its flow stress dependence on processing variables (for example, strain, strain rate, preheat temperature and die temperature), stress state in the deformation zone, its failure behavior, and the metallurgical transformations that characterize the alloy system to which is belongs
General Review 上清充通大￥ SHEAMGRAI DUD TONO UHTVEREETTY Reviews ● Frost Ashby Frost and Ashby,first of all,proposed Deformation Mechanism Map based on creep mechanisms applicable to lower strain rates. Temperature(°Cl Temperature [C) -200 200 400 00 800 -2000 200 400600.800 100012001400 104 Pure nickel d=1mm 10 10 10 Theoretical shear stress Ideal strength 10N 1/Sec Distocation glide H.T.creep 10 102 102 lattice ditfusion)、 101o5e Dislocation creep 102 10 10-3 D Power law- 102 10 (edw) L.T.creep core diffusion) eep、 104 10 10 10- Diffusional ftow 10 Coble 10 10T 10- 10 10 10- creep 108 10 Elastic regime Diffusional flow 107 10 10 Boundary diftusion Bulk diffusion 103 (Coble creep) (Nabarro-Herring 10a creep) 103 .4 .7 .89 1.0 10 .1 2 3 .3 4.5 .6.7 9 1.0 Homologous temperature (T/T) Homologous temperature(/Tm (a} Deformation mechanism map for(a)pure silver (b)nickel,showing stress-temperature space where different deformation mechanisms are rate controlling. Institute of Forming Technology Equipment 9
General Review Institute of Forming Technology & Equipment Reviews 9 Frost & Ashby Frost and Ashby, first of all, proposed Deformation Mechanism Map based on creep mechanisms applicable to lower strain rates. Deformation mechanism map for (a) pure silver (b) nickel, showing stress‐temperature space where different deformation mechanisms are rate controlling
General Review 上清充通大￥ SHEAMGRAI DUD TONO UHTVEREETTY Reviews ●Rishi Raj Extended the concept of Ashby's Map,using an atomistic method. Suitable to pure metal and dilute alloys. For many commercial alloys,difficult to determine the material parameters. TTM 10 0.4 0.6 0.8 102 Adiabatic 102 10 heating Ductile rupture Ductile fracture 4 3 Ductile 10-2 Melting uiens fracture Dynamic 10-1 Safe recrystal- Fail lization 10-4 10-2 Cavitation Fail 10-6 10-3 Wedge cracking 10-8 10-4 0.5TM TM 300 400500 600 700 800 900 Absolute temperature T(K) Institute of Forming Technology Equipment 10
General Review Institute of Forming Technology & Equipment Reviews 10 Rishi Raj Extended the concept of Ashby’s Map, using an atomistic method. Suitable to pure metal and dilute alloys. For many commercial alloys, difficult to determine the material parameters