Study On Magnetic Performance Of Austenitic Stainless Steel Guide Tube On Different Phase During Cold Processes And Welding

The electromagnetic flowmeter is a kind of measuring equipment commonly used in the industry.The fluid in the basin generates an induced electromotive force on both sides of the draft tube by cutting the magnetic induction line,and converts the volume of the water passage through a certain period of time by a known amount such as a cross-sectional area.flow.The processing of the largediameter draft tube is mainly made by welding after the coiled plate,and the composition of the cylinder material will undergo a phase change during the process to produce a magnetic conductive substance.The presence of an additional magnetic field in the draft tube in the working magnetic field causes interference with the original magnetic field distribution,which reduces the accuracy and reliability of the electromagnetic flowmeter.So,this paper firstly cold-processes the 304 and 310 S austenitic stainless steels commonly used in the industry,and measures the composition changes of the two materials after processing,and performs magnetic analysis.Based on this,the suitable cylinder materials are selected.Next,a welding process is performed to measure the composition change in the weld and perform magnetic analysis.Finally,the solution treatment is used to eliminate the magnetic properties of the processed material.Through some experiments,the main conclusions are as follows:(1)When austenitic stainless steel 304 and 310 S are cold-deformed,304 austenitic stainless steel will undergo martensitic transformation but 310 S steel is inconvenient,because 310 S steel has higher nickel content and lowers stretching.The free energy of austenite in the state makes the phase stable and stable in the tensile state of austenite.When the shape variable is large enough,the austenite grains are shattered under tension.(2)The cold-processed 304 austenitic stainless steel is a ferromagnetic material with a magnetic permeability of 1.2,which is due to the formation of bodycentered cubic martensite and ferrite during plastic deformation,resulting in magnetic permeability of the material.Therefore,this topic selects 310 S austenitic stainless steel as the material of the electromagnetic flowmeter guide tube.(3)The 301 S austenitic stainless steel after welding also has a certain magnetic permeability,and the size is 1.0~1.2.This is because the main components of the weld are austenite and ferrite.When the weld is initially formed,it is mainly austenite.If it is slowly cooled,the composition of the weld is austenite,ferrite and a mixed structure of carbides of Cr and Fe.(4)Reheating the weld can re-austenite the internal components of the weld,and maintain the austenite structure at room temperature after solution heat treatment,so that the weld can maintain the austenite structure and reduce the magnetic permeability of the material.,providing a good material basis for improving the accuracy of the electromagnetic flowmeter(5)The deviation of the magnetic induction B distribution and the air in the untreated 310 S austenitic stainless steel guide tube is in the order of 102,and the deviation after the solution treatment is in the order of 103,after the heat treatment,the guide tube The deviation value is reduced by an order of magnitude.The solution treatment improves the signal-to-noise ratio of the flowmeter and has a positive impact on the accuracy of the equipment.