Analysis Of Processing Map Theory And The Implementation Of Processing Map Technology

Workability refers to the relative ease with which a material can be shaped through plastic deformation. In recent decades, several models and instability theories have been proposed for the evaluation of hot workability. One of the most promising methods is the approach of processing map based on Dynamic Materials Model (hereafter DMM) which have been widely applied to design and optimize materials hot working process with the aim of realizing the control of microstructures and properties of hot worked materials.However, there is no unique criteria basd DMM that is applicable for all the materials in identifying the regions of instabilities in the respective processing maps. Under these circumstances, the process designers need to examine the applicability of the estabilished theories for the intended materials. Hence, much inconvenience has been brought to the research and production of materials. Besides, the construction pocess of processing maps is complicated, and thus a accurate, reliable and convenient method is needed for the application of the processing map technology.Based on the problems discussed above, the main work and results in this thesis are summarized as follows:(1) Another form of Prasad’s instability criterion based on Ziegler plastic flow theory is obtained: ξ(ε,T)=(?)m/(?)lnε+m2+m3<0(2) The comparative analysis of the applications of various exisiting instability theories on different materials has been carried out. Through theoretical analysis and experimental study, it is proved that Prasad’s instability criterion and Murty’s instability criterion, which are developed on the basis of Ziegler plastic flow theory, are similar. The up-movement between the instability maps based on the two criteria are also disscussed, and it is pointed out that it is the different physical significance and calculate methods of efficiency of power dissipation η and strain rate sensitivity m that lead to the up-movement. Besides, the verification of the uniformity of Gegel’s stability criterion and Malas’s stability criterion, based on Lyaponov theory, is also carried out. The research results may be helpful to provide a theoretical basis and guidance for the selection of instability theories of processing maps.(3) Processing Map Software (PMS) bas been developed on the basis of MATLAB GUI.(4) A comparative study is made between the processing maps for Ni-16Cr-8Fe alloy (IN600), powder metallurgy nimonic AP-1superalloy, as-cast magnesium Mg-11.5Li-Al, a new austenite-ferrite duplex stainless steel00Cr22NilMo017N, powder metallurgy2124Al-20Vol.Pct SiCp Metal Matrix Composite, aluminium alloy Al-Mg-Si, titanium alloy Ti53311S in the published literatures and constructed on the basis of PMS. It is demonstrated that the processing maps constructed by PMS can indicate exactly the evolving law of structures of materials under different hot deformation conditions. PMS provides a more convenient and effective tool for hot deformation of materials and has a general applicability and high accuracy. Besides, the similarity of Prasad’s instability criterion and Murty’s instability criterion are also further confirmed.