Dissimilar high-energy beam(HEB)welding is necessary in many industrial applications.Different composition of heat-affected zone(HAZ)and weld metal(WM)lead to variation in mechanical properties within the dissimilar j...Dissimilar high-energy beam(HEB)welding is necessary in many industrial applications.Different composition of heat-affected zone(HAZ)and weld metal(WM)lead to variation in mechanical properties within the dissimilar joint,which determines the performance of the welded structure.In the present study,appropriate filler material was used during electron beam welding(EBW)to obtain a reliable dissimilar joint between reduced-activation ferritic-martensitic(RAFM)steel and 316L austenitic stainless steel.It was observed that the layered structure occurred in the weld metal with 310S filler(310S-WM),which had the inferior resistance to thermal disturbance,leading to severe hardening of 310S-WM after one-step tempering treatment.To further ameliorate the joint inhomogeneity,two-step heat treatment processes were imposed to the joints and optimized.δ-ferrite in the layered structure transformed intoγ-phase in the first-step normalizing and remained stable during cooling.In the second-step of tempering,tempered martensite was obtained in the HAZ of the RAFM steel,while the microstructure of 310S-WM was not affected.Thus,the optimized properties for HAZ and 310S-WM in dissimilar welded joint was both obtained by a two-step heat treatment.The creep failure position of two dissimilar joints both occurred in CLAM-BM.展开更多
The effect of Zr addition(0.005,0.013,and 0.054 wt.%)on the microstructure and toughness of simulated coarse-grained heat-affected zone in high-strength low-alloy steels was revealed using a Gleeble 2000 thermal simul...The effect of Zr addition(0.005,0.013,and 0.054 wt.%)on the microstructure and toughness of simulated coarse-grained heat-affected zone in high-strength low-alloy steels was revealed using a Gleeble 2000 thermal simulator.It was observed that elongated MnS inclusions were formed in the lowest Zr-containing steel,while only pure equiaxed ZrO2 existed in the 0.054Zr steel(Zr content of 0.054 wt.%).Complex oxide-sulfide inclusions(ZrO2+MnS)with size of(1.40±0.25)μtm were formed in 0.013Zr steel(Zr content of 0.013 wt.%).The complex inclusions refined the prior austenite grain,and the nucleation of acicular ferrite was promoted compared to those of 0.005Zr steel(Zr content of 0.005 wt.%)and 0.054Zr steel.Consequently,the 0.013Zr steel possessed superior low-temperature impact toughness in relation to 0.005Zr and 0.054Zr steels.Thus,moderate Zr addition can be considered as an effective method to refine the structure and improve the mechanical properties of the coarse-grained heat-affected zone.展开更多
The scanning electron microscope,transmission electron microscope,optical microscope,X-ray diffraction and hardness tests were used to investigate the effect of deformation parameters in unrecrystallization range on m...The scanning electron microscope,transmission electron microscope,optical microscope,X-ray diffraction and hardness tests were used to investigate the effect of deformation parameters in unrecrystallization range on microstructural characteristics in Al-bearing hot-rolled transformation-induced plasticity steel.The thermomechanical-controlled processing was carried out with thermomechanical simulation machine,and the samples were compressed to compression strains of 0,0.15,0.25 and 0.35 at compression temperatures of 850,900 and 950°C.The results showed that the volume fraction of polygonal ferrite increased with the increasing compression strain,while the volume fraction of retained austenite reached the maximum value at compression strain of 0.25.The volume fraction of polygonal ferrite decreased with the increasing compression temperature,whereas the volume fraction of retained austenite possessed the maximum value at compression temperature of 850°C.Some granular retained austenite was present in uncompressed samples,and some pearlite appeared at large compression strain,while the hardness of the samples exhibited the similar variation tendency to the volume fraction of retained austenite.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 52001034, 51871030)Changzhou Sci & Tech Program, China (No. CJ20200078)+2 种基金Natural Science Foundation of Jiangsu Higher Education Institutions of China (No. 20KJB430013)the Top-notch Academic Programs of Jiangsu Higher Education Institutions, China (TAPP)the Priority Academic Program Development of Jiangsu Higher Education Institutions, China (PAPD)
基金supported financially by the National Magnetic Confinement Fusion Program of China (Nos.2014GB120000 and2014GB104003)the National Natural Science Foundation of China (No.51571026)
文摘Dissimilar high-energy beam(HEB)welding is necessary in many industrial applications.Different composition of heat-affected zone(HAZ)and weld metal(WM)lead to variation in mechanical properties within the dissimilar joint,which determines the performance of the welded structure.In the present study,appropriate filler material was used during electron beam welding(EBW)to obtain a reliable dissimilar joint between reduced-activation ferritic-martensitic(RAFM)steel and 316L austenitic stainless steel.It was observed that the layered structure occurred in the weld metal with 310S filler(310S-WM),which had the inferior resistance to thermal disturbance,leading to severe hardening of 310S-WM after one-step tempering treatment.To further ameliorate the joint inhomogeneity,two-step heat treatment processes were imposed to the joints and optimized.δ-ferrite in the layered structure transformed intoγ-phase in the first-step normalizing and remained stable during cooling.In the second-step of tempering,tempered martensite was obtained in the HAZ of the RAFM steel,while the microstructure of 310S-WM was not affected.Thus,the optimized properties for HAZ and 310S-WM in dissimilar welded joint was both obtained by a two-step heat treatment.The creep failure position of two dissimilar joints both occurred in CLAM-BM.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.51671149)Wuhan Science and Technology Program(Grant No.2019010701011382)+1 种基金Major Technology Innovation of Hubei Province(2016AAA022)111 Project.R.D.K.Misra gratefully acknowledges continued collaboration with WUST as Guest Professor.
文摘The effect of Zr addition(0.005,0.013,and 0.054 wt.%)on the microstructure and toughness of simulated coarse-grained heat-affected zone in high-strength low-alloy steels was revealed using a Gleeble 2000 thermal simulator.It was observed that elongated MnS inclusions were formed in the lowest Zr-containing steel,while only pure equiaxed ZrO2 existed in the 0.054Zr steel(Zr content of 0.054 wt.%).Complex oxide-sulfide inclusions(ZrO2+MnS)with size of(1.40±0.25)μtm were formed in 0.013Zr steel(Zr content of 0.013 wt.%).The complex inclusions refined the prior austenite grain,and the nucleation of acicular ferrite was promoted compared to those of 0.005Zr steel(Zr content of 0.005 wt.%)and 0.054Zr steel.Consequently,the 0.013Zr steel possessed superior low-temperature impact toughness in relation to 0.005Zr and 0.054Zr steels.Thus,moderate Zr addition can be considered as an effective method to refine the structure and improve the mechanical properties of the coarse-grained heat-affected zone.
基金the support from National Natural Science Foundation of China(No.51504063).R.D.K.Misra,an honorary professor,also acknowledges the continued collaboration with Northeastern University by providing guidance to students in research.
文摘The scanning electron microscope,transmission electron microscope,optical microscope,X-ray diffraction and hardness tests were used to investigate the effect of deformation parameters in unrecrystallization range on microstructural characteristics in Al-bearing hot-rolled transformation-induced plasticity steel.The thermomechanical-controlled processing was carried out with thermomechanical simulation machine,and the samples were compressed to compression strains of 0,0.15,0.25 and 0.35 at compression temperatures of 850,900 and 950°C.The results showed that the volume fraction of polygonal ferrite increased with the increasing compression strain,while the volume fraction of retained austenite reached the maximum value at compression strain of 0.25.The volume fraction of polygonal ferrite decreased with the increasing compression temperature,whereas the volume fraction of retained austenite possessed the maximum value at compression temperature of 850°C.Some granular retained austenite was present in uncompressed samples,and some pearlite appeared at large compression strain,while the hardness of the samples exhibited the similar variation tendency to the volume fraction of retained austenite.
