Expandable Screen-based Works The Twip Steel Development And Performance Analysis

This paper adopts the design method of alloys which is based on stacking fault energy and processing mode of hot rolling after vacuum metling, projecting and preparing the steel which can be used in expandable screen shell with high product of strength and elongation, anti-acid crossion, large expansion ratio.The steel is consists of 0.1～0.3%C,25% Cr,4～10%Mn,2%Ni,2%Al,1%Si,0.5%Mo,the rest is Fe.In this paper, the mechanical property and plastic behavior of TWIP steel for expandable screen shell are studied by the means of tensile test at the temperature of 25℃～300℃and analyzing with OM,XRD,SEM,TEM and EDS. The anti-corrosion property and the electrochemical corrosion mechanism of the mentioned steel are researched by the electrochemical corrosion experiment of taking calomel electrode as reFerence electrode, 5%NaCl+0.5%CH3COOH as etchant solution, and 50mV/min as scanning speed, combined with analyzations of the corrosion potential Ecorr and corrosion current Icorr depending on CorrView. In addition,in this paper corrosion poplarization curves is determined by moving-potential method. Moreover,this artiCle discusses the mechanical property of TWIP steel-based expandable tube in the course of expansion and casing collapse by the ways of ANSYS10.0 which can work out the problem of large deformation and non-linear frictional contact.Studies show that the designed steel whose plastic behavior is twinning induced plasticity has high strength, high plasticity and anti-corrosion property.The anti-collapse capability of the designed steel-based expandable screen shell after expanding is better than 316L stainless steel.The corrosion resistance of designed steel has been reduced by the deformation. And the anti-corrosion capability after high temperature deformation is more superior than that after low temperature deformation.Furthermore,a theoretical formula of the relation of primary crystalline grown size and solid solution temperature with time is proposed based on the theory of recrystallization, shown below. Dt=K'e-Qm/2RT·t1/2 Similarly,a relation of the number and size of the annealing twins and solid solution time,shown as follows. Besides,a phenomenon is discovered that the annealing twins in grain could decrease the shortage of Cr in the grain boundary and contribute to anti-corrosion property.and the main reason of reducing performance after deformation is the mechanochemical efFect of corrosion.The synthesis result indicates that the designed steel is more suitable as materials of expandable screen shell than 316L strainless steel,especially encountering in thermal production wells of heavy oil,deep wells,superdeep wells, extradeep wells which has more need of large expansion.The studies in this paper have provided a method to design and choose the materials of expandable screen shell.This is of important significance to the expandable screen shell in wide using and the development of the oil and gas in theory and practice.