Effect Of Re And Si,Mn Element On Microstructure And Mechanical Properties Of ZG06Cr13Ni4Mo Stainless Steel

In this paper,ZG06Cr13Ni4Mo low-carbon martensitic stainless steel produced in runner nozzle was taken as the research object,and several ZG06Cr13Ni4Mo martensitic stainless steels with different Re（La and Ce mixed rare earth）and Si and Mn element contents were designed.By means of microstructure detection and mechanical properties test,the influence and mechanism of Re and Si,Mn element on the microstructure and mechanical properties of this material were explored,which could provid alternative materials for the preparation and engineering application of high-strength low-carbon martensitic stainless steel for ultra-high-head water turbine.The main contents and conclusions of this paper are as follows:（1）Under the condition of vacuum and deoxidization by adding aluminum,the addition of 0.05wt%and 0.12wt%Re could greatly reduce the content of harmful elements such as gas,enhancing the mechanical properties of ZG06Cr13Ni4Mo martensitic stainless steel and improving its microstructure.Compared with 0.05wt%,the high dosage of 0.12wt%had a better effect.When the high dosage of 0.12wt%,the yields of Ce and La element were 43.06%and 16.67%respectively,and the contents of O,H,N,S and P were 145Jppm,2ppm,60ppm,24ppm and 19ppm respectively.The yield strength of the specimen was 727MPa,the tensile strength was 846MPa,elongation and shrinkage were18%and 65%.The number of inclusions in the microstructure was low and the size of inclusions in the microstructure was small,and the rating result was fine system grade 0.5;forming fine spherical oxide inclusions which were rare earth compounds wrapped with sulfides or oxygen sulfides;the size of martensitic laths and the number ofδ-ferritic phases were smaller,and the morphology ofδ-phase changed from irregular morphology such as long strips and triangles to fine lumps.（2）With the addition of Si element,the strength and hardness of ZG06Cr13Ni4Mo stainless steel first increased and then decreased,the plasticity and room temperature impact absorbed work decreased,and the carbide number andδ-ferrite distribution also changed.When the addition of Si element was 1.1 wt%,the material had the best strength and toughness,and the mechanical property indexes were:R_m=850MPa,R_p0.2=608MPa,A=19.5%,Z=59%,A_kv=72.5 J.（3）Mn element could enhance the tensile strength of ZG06Cr13Ni4Mo stainless steel,it had little effect on the yield strength,with the addition of Mn element,plasticity and room temperature impact absorbed work decreased,martensitic lath size reduced.When the addition of Mn element was 1.0 wt%,the material had the best strength and toughness,the mechanical properties indexes were:R_m=845MPa,R_p0.2=546 MPa,A=19%,Z=64%,A_kv=105 J.