FSW and TIG were conducted on 316L stainless steel.Variation during microstructure and properties in joints obtained by different welding methods was studied.The results show that the effect of severe mechanical stirr...FSW and TIG were conducted on 316L stainless steel.Variation during microstructure and properties in joints obtained by different welding methods was studied.The results show that the effect of severe mechanical stirring and intense plastic deformation creat a fine recrystallized grain in the welding joint during FSW.As for TIG,the temperature of welding joint exceeds the melting point of welded material itself.The entire welding process belongs to the solidification of a small molten pool;and the microstructure of the joint takes on a typical casting structure.When the welding parameters were selected appropriately,the average ultimate tensile strength of FSW joints can reach 493 MPa,which is 83.6%of base metal;the average elongation is 52.1%of base metal.The average ultimate tensile strength of TIG joints is 475 MPa, which is 80.5%of base metal;the average elongation is 40.8%of base metal.The tensile test of FSW joints is superior to the TIG joints.The microhardness of FSW joint compared to base metal and TIG joint having a significant improvement,which arel95.5 HV,159.7 HV and 160.7 HV,respectively;grain refinement strengthening plays an important role in enhancing the microhardness.The electrochemical corrosion tests show that the joint of FSW 316L austenitic stainless steel has a good corrosion resistance.展开更多
The surface spinning strengthening(3S)mechanism and fatigue life extension mechanism of 316L stainless steel welded joint were systematically elucidated by microstructural analyses and mechanical tests.Results indicat...The surface spinning strengthening(3S)mechanism and fatigue life extension mechanism of 316L stainless steel welded joint were systematically elucidated by microstructural analyses and mechanical tests.Results indicate that surface gradient hardening layer of approximately 1 mm is formed in the base material through grain fragmentation and deformation twin strengthening,as well as in the welding zone composed of deformedδ-phases and nanotwins.The fatigue strength of welded joint after 3S significantly rises by 32%(from 190 to 250 MPa),which is attributed to the effective elimination of surface geometric defects,discrete refinement ofδ-Fe phases and the appropriate improvement in the surface strength,collectively mitigating strain localization and surface fatigue damage within the gradient strengthening layer.The redistributed fineδ-Fe phases benefited by strong stress transfer of 3S reduce the risk of surface weak phase cracking,causing the fatigue fracture to transition from microstructure defects to crystal defects dominated by slip,further suppressing the initiation and early propagation of fatigue cracks.展开更多
Surface engineering technology is a suitable method for coatings on the metal surfaces or performing surface modification treatment, which can improve corrosion resistance and biocompatibility of metals. In this resea...Surface engineering technology is a suitable method for coatings on the metal surfaces or performing surface modification treatment, which can improve corrosion resistance and biocompatibility of metals. In this research, corrosion behavior of Nb coating on H2SO4 and HNO3 treated AISI stainless steel 316L （SS） was evaluated. Nb coating was carried out using physical vapor deposition process on the SS. Characterization techniques including scanning electron microscopy （SEM） and energy dispersive X-ray （EDX） technique were used to investigate the microstructure and morphology of the coated and treated SS. Electrochemical potentiodynamic tests were performed in two types of physiological solutions and compared with the pristine SS specimens. Cyclic polarization tests were performed to evaluate resistivity against pitting. Experimental results indicate that Nb coating and surface treatment of the SS had a positive effect on improvement of corrosion behavior. The decrease in corrosion current densities was significant for coated and treated specimens. The corrosion current density was much lower than the values obtained for pristine specimens.展开更多
The aim of this studies at simultaneous improvement of the corrosion behavior and biocompatibility of metallic implant and bone Osseointegration simultaneously. Stainless steel 316L （SS） was used as metallic substra...The aim of this studies at simultaneous improvement of the corrosion behavior and biocompatibility of metallic implant and bone Osseointegration simultaneously. Stainless steel 316L （SS） was used as metallic substrate and after surface treatment with 15 vol.% sulfuric acid, it was coated with hydroxyapatite coating employing plasma - spraying process. Structure characterization techniques including XRD, SEM and EDX were also utilized to investigate the microstructure, morphology, and crystallinity of the coating. Electrochemical potentiodynamic tests were performed in two types of physiological solutions in order to determine and compare the corrosion resistance behavior of the coated and uncoated specimens as an indication of biocompatibility. The results indicate that the surface treatment and hydroxyapatite coating improve the corrosion resistance behavior of SS. The corrosion current density of the surface treated and the hydroxyapatite coated SS also decrease. These also show that surface treated and hydroxyapatite coated SS can be used as human body implants with the goals of corrosion resistance improvement （biocompatibility） and bone osseointegration.展开更多
文摘FSW and TIG were conducted on 316L stainless steel.Variation during microstructure and properties in joints obtained by different welding methods was studied.The results show that the effect of severe mechanical stirring and intense plastic deformation creat a fine recrystallized grain in the welding joint during FSW.As for TIG,the temperature of welding joint exceeds the melting point of welded material itself.The entire welding process belongs to the solidification of a small molten pool;and the microstructure of the joint takes on a typical casting structure.When the welding parameters were selected appropriately,the average ultimate tensile strength of FSW joints can reach 493 MPa,which is 83.6%of base metal;the average elongation is 52.1%of base metal.The average ultimate tensile strength of TIG joints is 475 MPa, which is 80.5%of base metal;the average elongation is 40.8%of base metal.The tensile test of FSW joints is superior to the TIG joints.The microhardness of FSW joint compared to base metal and TIG joint having a significant improvement,which arel95.5 HV,159.7 HV and 160.7 HV,respectively;grain refinement strengthening plays an important role in enhancing the microhardness.The electrochemical corrosion tests show that the joint of FSW 316L austenitic stainless steel has a good corrosion resistance.
基金financially supported by the Science and Technology Cooperation Project between Jilin Province and Chinese Academy of Sciences under grant No.2020SYHZ0017the Fundamental Research Funds for the Central Universities under Grant No.N2202003+1 种基金also partially supported by the National Natural Science Foundation of China(NSFC)under Grant Nos.52100003,52171108 and 52321001the Liaoning Revitalization Talents Program under Grant No.XLYC1808027.
文摘The surface spinning strengthening(3S)mechanism and fatigue life extension mechanism of 316L stainless steel welded joint were systematically elucidated by microstructural analyses and mechanical tests.Results indicate that surface gradient hardening layer of approximately 1 mm is formed in the base material through grain fragmentation and deformation twin strengthening,as well as in the welding zone composed of deformedδ-phases and nanotwins.The fatigue strength of welded joint after 3S significantly rises by 32%(from 190 to 250 MPa),which is attributed to the effective elimination of surface geometric defects,discrete refinement ofδ-Fe phases and the appropriate improvement in the surface strength,collectively mitigating strain localization and surface fatigue damage within the gradient strengthening layer.The redistributed fineδ-Fe phases benefited by strong stress transfer of 3S reduce the risk of surface weak phase cracking,causing the fatigue fracture to transition from microstructure defects to crystal defects dominated by slip,further suppressing the initiation and early propagation of fatigue cracks.
基金support of this research by Isfahan University of technology
文摘Surface engineering technology is a suitable method for coatings on the metal surfaces or performing surface modification treatment, which can improve corrosion resistance and biocompatibility of metals. In this research, corrosion behavior of Nb coating on H2SO4 and HNO3 treated AISI stainless steel 316L （SS） was evaluated. Nb coating was carried out using physical vapor deposition process on the SS. Characterization techniques including scanning electron microscopy （SEM） and energy dispersive X-ray （EDX） technique were used to investigate the microstructure and morphology of the coated and treated SS. Electrochemical potentiodynamic tests were performed in two types of physiological solutions and compared with the pristine SS specimens. Cyclic polarization tests were performed to evaluate resistivity against pitting. Experimental results indicate that Nb coating and surface treatment of the SS had a positive effect on improvement of corrosion behavior. The decrease in corrosion current densities was significant for coated and treated specimens. The corrosion current density was much lower than the values obtained for pristine specimens.
文摘The aim of this studies at simultaneous improvement of the corrosion behavior and biocompatibility of metallic implant and bone Osseointegration simultaneously. Stainless steel 316L （SS） was used as metallic substrate and after surface treatment with 15 vol.% sulfuric acid, it was coated with hydroxyapatite coating employing plasma - spraying process. Structure characterization techniques including XRD, SEM and EDX were also utilized to investigate the microstructure, morphology, and crystallinity of the coating. Electrochemical potentiodynamic tests were performed in two types of physiological solutions in order to determine and compare the corrosion resistance behavior of the coated and uncoated specimens as an indication of biocompatibility. The results indicate that the surface treatment and hydroxyapatite coating improve the corrosion resistance behavior of SS. The corrosion current density of the surface treated and the hydroxyapatite coated SS also decrease. These also show that surface treated and hydroxyapatite coated SS can be used as human body implants with the goals of corrosion resistance improvement （biocompatibility） and bone osseointegration.
