Research On Texture And Residual Stress Of 0Cr21Ni6Mn9N Austenitic Stainless Steel Pipe

0Cr21Ni6Mn9N(21-6-9N)steel is a kind of Cr-Ni-Mn austenitic stainless steel strengthened by Nitrogen.Owing to its high strength-toughness,excellent resistance to corrosion and high pressure,and good high temperature oxidation resistance,21-6-9N steel becomes a suitable candidate material for large size aerospace tubes.This steel has been used in fabricating the air-conditioning duct system,exhaust tail pipe,and hydraulic system conduit of various planes in the western developed countries.Although the domestically-made 21-6-9N steel tube has reached the standard requirements of the mechanical properties and batch production,the domestically-made tubes are more easy to crack during the flaring comparing to the imported-made tubes.Considering that the residual stress and texture are important parameter in influencing the flaring cracks,there are important values of theory and application to research the residual stress and texture of the 21-6-9N steel tubes and its effects on the flaring properties of tubes.The residual stress and texture of domestically-made and imported-made tubes with different specifications were tested by X ray diffraction technique,and its influences on the flaring properties of the tubes are analyzed.The results show that the tubes processing has some influence on texture intensity,but little influence on texture types,which has no significant influence on the flaring property.However,the tubes processing has significant influence on residual stress,which effects the flaring property of 21-6-9N steel tubes.Domestically-made tubes exist circumferential and axial residual tension stress,resulting in poor performance of plastic deformation and flaring process.The reason is that the residual tension stress will be superimposed with flaring stress,which changes the stress state at the maximum diameter of flaring region from one tension stress to two tension stress.Imported-made tubes exist circumferential and axial residual compression stress,resulting in decreasing of circumferential tension stress and increasing of axial compress ion stress at the maximum diameter during the flaring process,which is helpful to the flaring performance of the tubes.the tubes processing has influence on the texture and residual stress with different influence degree.