Effect Of Rare Earth Ce On Microstructure And Properties Of X100 Pipeline Steel

Natural gas in my country is gradually gaining popularity,but natural gas in my country is mainly in the western region and imported.Due to the long distance in the natural gas transmission process and the harsh environment,high performance is required for pipeline steel.Moreover,the exploitation of oil fields in our country is gradually emerging.Pipeline steel has already passed the seabed in various environments in the process of oil transportation,which puts great demands on the mechanical properties and corrosion resistance of pipeline steel.This article combines Inner Mongolia's natural advantage"rare earth"to add trace rare earth elements to pipeline steel,to explore the effect of rare earth on the mechanical properties of pipeline steel has been corrosion resistance.Use microstructure observation,mechanical performance test and other test methods to perform performance testing;and 3.5%NaCl solution was used to simulate seawater to conduct corrosion test on the experimental steel.The corrosion rate of the experimental steel was obtained by the weightlessness method,the microstructure,corrosion morphology,corrosion products of the experimental steel after corrosion were observed,and the electrochemical analysis system was used to study the effect of rare earth Ce on the corrosion performance of X100 pipeline steel.Concluded as follow:The metallographic microstructure observation results show that the addition of rare earth in the test steel can not only play a role in refining the grains,but also can transform the large-sized and sharp-angled Al₂O₃ and MnS inclusions into small-sized spherical rare earth compound inclusions,and the distribution is dispersed.In the steel base,it is beneficial to improve the performance of the test steel.The room temperature tensile and low temperature impact test results show that when Ce is added at 0.0049%,the tensile strength is increased by 20%and the yield strength is increased by 25%compared with 0#steel without rare earth.The mechanical properties of the test steel Have improved.After the test steel was immersed in the 3.5%NaCl corrosion solution for 45 days,the corrosion rate of the experimental steel added with rare earth was significantly lower than that of the experimental steel without added rare earth.It can be seen from the corrosion morphology of the sample steel that as the content of rare earth Ce increases,a continuous and dense inner rust layer is formed on the surface of the steel base of the test steel,effectively preventing the corrosion ions from contacting the surface of the steel base.Therefore,the rare earth contributes to the improvement of the corrosion resistance of the test steel.The content of FeOOH in the corrosion product of the rare earth test steel is higher than that of the test steel without the addition of rare earth,and the content of Fe₃O₄ is lower than that of the test steel without the addition of rare earth,so the content of FeOOH and Fe₃O₄ in the inner rust layer causes the corrosion resistance of the test steel Had an impact.The electrochemical test results of the test steel show that the corrosion current density of the test steel is inversely proportional to the amount of rare earth Ce added.When the rare earth Ce content is 0.0049%,the corrosion current density is the smallest;the test steel capacity arc resistance radius and Rp value It is directly proportional to the amount of rare earth Ce added.When the rare earth content is 0.0049%,its capacitive arc radius and Rp value are the largest.