高钢级输氢管线钢L415MH组织性能研究OA

To meet the demand for high-grade hydrogen pipeline steel in the Kangbao—Caofeidian long-distance hydrogen pipeline project,L415MH steel is taken as the research object.The steel adopts a chemical composition system with low carbon,low manganese,low phosphorus and low sulfur,and is incorporated with appropriate contents of chromium,nickel and molybdenum,as well as niobium,vanadium and titanium for microalloying.The steel plates and corresponding pipes are manufactured via high-purity smelting combined with the thermomechanical control process(TMCP).Tests on microstructure,mechanical properties and hydrogen embrittlement sensitivity are carried out.The results indicate that the microstructure of the L415MH pipe base metal is dominated by acicular ferrite and polygonal ferrite.The heat-affected zone(HAZ)is composed of polygonal ferrite,acicular ferrite and granular bainite,and the weld metal consists of acicular ferrite and granular bainite.The overall properties of the steel plate are better than those of the steel pipe,and all mechanical indicators comply with relevant standards.No hydrogen-induced cracks are observed.The base metal presents excellent hydrogen resistance under the environment of 7.2 MPa high-pressure pure hydrogen.Although the hydrogen embrittlement sensitivity of the weld metal and HAZ rises slightly,it still stays within the limit values for engineering design.In summary,the composition design,production process,microstructure,mechanical properties and hydrogen compatibility of this L415MH steel can meet the service requirements of high-pressure long-distance hydrogen pipelines.It can also provide theoretical basis and technical reference for the research,development and engineering application of similar hydrogen pipeline steels.