Grain orientation evolutions and texture formation based on the Taylor principles offer important references to reveal crystallographic mechanisms of deforma- tion behaviors. Strain equilibrium between grains is achie...Grain orientation evolutions and texture formation based on the Taylor principles offer important references to reveal crystallographic mechanisms of deforma- tion behaviors. Strain equilibrium between grains is achieved in Taylor theory, however, stress equilibrium has not yet been reached perfectly even in many modifications of the theory though the textures predicted become very close to those of experimental observations. A reaction stress model is proposed, in which mechanical interactions between grains are considered in details and grain deformation is conducted by penetrating and non-penetrating slips. The new model offers both of the stress and strain equilibria and predicts the same textures indicated by Taylor theory. The rolling texture simulated comes very close to the experimental observations if the relaxation effect of the non-penetrating slips on the up-limits of reaction stresses is included. The reaction stress principles open theoretically a new field of vision to consider deformation behaviors of poiycrystaliine materials, whereas the Taylor principles become unnecessary both theoretically and practically. Detailed engineering conditions have to be included in simulations if the deformation textures of industrial products should be predicted.展开更多
The original Taylor principles offer identical intergranular strain equilibrium without stress equilibrium in metals during deformation. In reality, however, the stress and strain equilibria are maintained individuall...The original Taylor principles offer identical intergranular strain equilibrium without stress equilibrium in metals during deformation. In reality, however, the stress and strain equilibria are maintained individually for different grains. As key points, the principles have become a prerequisite predominantly in the current theories, which unreasonably indicate that strains instead of stresses induce grain deformation despite reaching the stress equilibrium by complicated combinations of the activation of slip systems or other crystallographic mechanism via different approaches. Real intergranular equilibria can be traced if mechanical interactions together with the external loading are considered step by step. In this work, several penetrating and non-penetrating slips were used to obtain the necessary elastic and plastic strain tensors of different grains in a natural manner. Without the Taylor principles, the stress and strain equilibria can be reached naturally, simply, easily, reasonably, and individually without complicated calculations. Results of the experimental observation conformed with the predicted deformation texture when certain important engineering stress conditions are included in the simulation. Therefore, the Taylor principles for plastic deformation of polycrystalline metals should now be disregarded.展开更多
The equilibrium of intergranular stress and strain can be realized simultaneously,whereas five independent slip systems of the Taylor principle and the criterion of minimal internal work are unnecessary.In fact,the Ta...The equilibrium of intergranular stress and strain can be realized simultaneously,whereas five independent slip systems of the Taylor principle and the criterion of minimal internal work are unnecessary.In fact,the Taylor principle applied in current theories is incorrect both in practice and theory,in which the activation mechanism of plastic deformation systems must violate the Schmid’s law and deviate from the elastic-plastic characteristics of deformed matrix.The intergranular reaction stress(RS)during deformation can be calculated according to Hooke’s law and elastic limit without additional subjective presupposition,therefore the RS theory is established intuitively.Under the combination of the RS(the intergranular elastic effect)and the external loading the slips penetrating grains are activated and produce deformation texture,but certain non-penetrating slips near grain boundaries will become active(the intergranular plastic effect)and produce some random texture when a RS reaches the yield strength of grains.The RS theory is simple,intuitive and reasonable,based on which the texture simulation can well reproduce the texture formation of various metals under different external loadings and under different crystallographic mechanisms.展开更多
文摘Grain orientation evolutions and texture formation based on the Taylor principles offer important references to reveal crystallographic mechanisms of deforma- tion behaviors. Strain equilibrium between grains is achieved in Taylor theory, however, stress equilibrium has not yet been reached perfectly even in many modifications of the theory though the textures predicted become very close to those of experimental observations. A reaction stress model is proposed, in which mechanical interactions between grains are considered in details and grain deformation is conducted by penetrating and non-penetrating slips. The new model offers both of the stress and strain equilibria and predicts the same textures indicated by Taylor theory. The rolling texture simulated comes very close to the experimental observations if the relaxation effect of the non-penetrating slips on the up-limits of reaction stresses is included. The reaction stress principles open theoretically a new field of vision to consider deformation behaviors of poiycrystaliine materials, whereas the Taylor principles become unnecessary both theoretically and practically. Detailed engineering conditions have to be included in simulations if the deformation textures of industrial products should be predicted.
基金This work was financially supported by the National Natural Science Foundation of China （Grant No. 51571024）.
文摘The original Taylor principles offer identical intergranular strain equilibrium without stress equilibrium in metals during deformation. In reality, however, the stress and strain equilibria are maintained individually for different grains. As key points, the principles have become a prerequisite predominantly in the current theories, which unreasonably indicate that strains instead of stresses induce grain deformation despite reaching the stress equilibrium by complicated combinations of the activation of slip systems or other crystallographic mechanism via different approaches. Real intergranular equilibria can be traced if mechanical interactions together with the external loading are considered step by step. In this work, several penetrating and non-penetrating slips were used to obtain the necessary elastic and plastic strain tensors of different grains in a natural manner. Without the Taylor principles, the stress and strain equilibria can be reached naturally, simply, easily, reasonably, and individually without complicated calculations. Results of the experimental observation conformed with the predicted deformation texture when certain important engineering stress conditions are included in the simulation. Therefore, the Taylor principles for plastic deformation of polycrystalline metals should now be disregarded.
基金support given by the National Natural Science Foundation of China(Grant No.51571014).
文摘The equilibrium of intergranular stress and strain can be realized simultaneously,whereas five independent slip systems of the Taylor principle and the criterion of minimal internal work are unnecessary.In fact,the Taylor principle applied in current theories is incorrect both in practice and theory,in which the activation mechanism of plastic deformation systems must violate the Schmid’s law and deviate from the elastic-plastic characteristics of deformed matrix.The intergranular reaction stress(RS)during deformation can be calculated according to Hooke’s law and elastic limit without additional subjective presupposition,therefore the RS theory is established intuitively.Under the combination of the RS(the intergranular elastic effect)and the external loading the slips penetrating grains are activated and produce deformation texture,but certain non-penetrating slips near grain boundaries will become active(the intergranular plastic effect)and produce some random texture when a RS reaches the yield strength of grains.The RS theory is simple,intuitive and reasonable,based on which the texture simulation can well reproduce the texture formation of various metals under different external loadings and under different crystallographic mechanisms.
