| Duplex stainless steel S32760 has exceptional toughness and weldability of the austenite phase and high strength,chloride resistance,and stress corrosion resistance of the ferrite phase due to its structure comprising austenite phase and ferrite phase.It can be better used in a highly corrosive marine environment and provide a powerful weapon for building a marine power.However,because S32760 has a viscous effect in lofty strain rates,the flow stress proliferates sharply as the strain rate piles up,making S32760 a knotty machining material.In the cutting process,the strain rate has reached a very high value.Material deformation should take into consideration not just the material's elasticity and plasticity,but also the effect of viscosity.Aiming at the viscous effect of cutting dual phase stainless steel S32760,starting with the theory of deformation essence,this paper analyzes the rejig of plastic deformation control mechanism,and establishes constitutive model of ferrite-austenite dual-phase material based on the coupling of mechanism transformation and two-phase viscous effect.Dynamic compression experiments are utilized to characterize the strain rate and temperature effect of S32760.The influence of strain rates on chip geometric and corporal characteristics is scrutinized.Finally,the viscosity effect of S32760 is verified by orthogonal cutting simulation.It has theoretical and practical significance to reveal the machinability of duplex stainless steel and realize the high-efficiency and high-precision machining of duplex stainless steel parts.To begin,the nature of plastic deformation is employed to investigate the alteration of the plastic deformation control mechanism as the material's strain rate varies.Based on the geometric characteristics of the cutting layer,after establishing the renewal phoney of strain rate and cutting speed,the upshot of cutting speed on the plastic deformation control machine-made is scrutinized,and a theoretical model of strain rate under the control of various mechanisms is developed.By comparing the flow stress model of duplex stainless steel material and Newtonian fluid,the fluid-like viscosity reaction of duplex stainless steel in the cutting process is elucidated,to show the plastic deformation connection mechanism of the two phases ferrite and austenite,and to erect the constitutive model of duplex stainless steel.Then,dynamic compression experiment were designed for S32760 of divergent strain rates and temperatures to obtain a stress-strain relationship diagram for S32760,discover the strain rate and temperature sensitivity of S32760,and the stress-strain curves at different strain rates are used to quantitatively divide and model the three stages of deformation.The diagnostic threshold temperature that causes the flow stresses to decline and the critical strain rate that causes the flow stresses to rise are determined.The validity of the flow stresses model is formed by comparing experimental features to the model.Then,the S32760 cutting experiment was then constructed,the microscopic morphology of the chips was analyzed using a scanning electron microscope,the microscopic changes in the ferrite phase and austenite phase in the chips were compared,and the internal mechanism of the strain rate effect was described.Combining the chip shape and calculating the degree of chip sawtooth at different cutting speeds,the effect of strain rate on chip geometric characteristics is studied.By measuring the hardness of S32760 chips at different positions at different cutting speeds,the variation law of chip hardness is analysed,and the effect of strain rate on chip bodily characteristics is studied.Finally,Abaqus is used to simulate the cutting process of duplex stainless steel S32760.The accuracy of the simulation model is verified by the sawtooth degree of chips,and the temperature effect and strain rate effect of S32760 are verified by simulating the chip stress at different temperatures and cutting speed,the viscous effect of S32760 owing to temperature reduction and strain rate increase is demonstrated. |
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