Due to isothermal heat treatment or welding,duplex stainless undergoes a variety of decomposition processes at a temperature ranging from 300 - 1 100℃,which could form inter-metallic phases likeσ-phase and xphase,as...Due to isothermal heat treatment or welding,duplex stainless undergoes a variety of decomposition processes at a temperature ranging from 300 - 1 100℃,which could form inter-metallic phases likeσ-phase and xphase,as well as Cr2N and M23C6,etc.These processes are not only influenced by temperature and cooling speed, but also are affected by alloy element content.The purpose of the research was to work out the qualitative and quantitative analysis of precipitate phases in 2 205 duplex stainless steel with different isothermal heat treatment situation.After choosing the electrolyte and electrolytic systems,we use electrochemical method to extract precipitate phases from the matrix.Scanning electron microscope（SEM） and X-ray diffraction（XRD） were used to examine their modality and structure.Particle size distribution was performed by dynamic laser scattering sizer （DLS-Sizer）.Furthermore,oxygen-nitrogen analyzer and carbon-sulfur analyzer were applied to measure the content of nitrogen and carbon in precipitate phases.Separation and quantitative analysis of precipitate phases were carried out by wet chemical analysis and inductively coupled plasma spectrometry（ICP）.In a word,combining chemical and physical methods,our research reveals the transformation of precipitate phases’species,content, elemental composition and particle size distribution during different isothermal heat treatment situation.展开更多
介绍了10Cr21Mn16NiN钢线材成分设计、增氮原理、冶炼工艺、轧制和固溶工艺、Cr_(2)N相析出的生产工艺。采用30 t AOD精炼,吹氮气增氮,精炼后期加氮化锰。轧制时采用1240℃加热、控轧控冷,保证了盘条表面质量,避免了中心缩孔等问题;固...介绍了10Cr21Mn16NiN钢线材成分设计、增氮原理、冶炼工艺、轧制和固溶工艺、Cr_(2)N相析出的生产工艺。采用30 t AOD精炼,吹氮气增氮,精炼后期加氮化锰。轧制时采用1240℃加热、控轧控冷,保证了盘条表面质量,避免了中心缩孔等问题;固溶温度应控制在1100℃左右,且保温30 min后快冷,可防止Cr_(2)N相析出。成功生产出表面质量和性能优良的10Cr21Mn16NiN不锈钢线材。展开更多
Precipitation behavior of P550 steel for non-magnetic drill collars was investigated by microstructure characterization as well as thermodynamic calculation.The results demonstrate that the main precipitate formed at ...Precipitation behavior of P550 steel for non-magnetic drill collars was investigated by microstructure characterization as well as thermodynamic calculation.The results demonstrate that the main precipitate formed at 650–900℃was cellular Cr_(2)N,and its precipitation depended heavily on the aging temperature.The most sensitive precipitation temperature of cellular Cr_(2)N was 750℃.At 750℃,the cellular Cr_(2)N exhibited fast-slow precipitation kinetics with the aging time prolonging.The initial precipitation of cellular Cr_(2)N was governed by the short-range intergranular diffusion of Cr.During long-term aging,its growth was controlled by the long-range bulk diffusion of Cr.In addition,cellular Cr_(2)N induced the precipitation of r phase ahead of the cell after long period of aging.Increasing the nitrogen content resulted in the increment of both the nucleation site and the driving force for the cellular Cr_(2)N,which jointly promoted its precipitation.展开更多
Aiming at serious catastrophic oxidation problem of super-austenitic stainless steel S32654,the influence of different rare earth elements on its oxidation behavior was comparatively investigated at 1200℃.The mechani...Aiming at serious catastrophic oxidation problem of super-austenitic stainless steel S32654,the influence of different rare earth elements on its oxidation behavior was comparatively investigated at 1200℃.The mechanism of Y significantly improving high-temperature oxidation resistance of S32654 was unveiled.The results demonstrated that Y played much better beneficial roles than Ce and La in the initial formation of oxide layer:(1)Y promoted Cr segregation to steel surface to combine with O;(2)its preferential oxidation provided nucleation cores for Cr_(2)O_(3).Both roles jointly promoted the selective oxidation of Cr and then the formation of protective Cr-rich oxide layer.This provided good prerequisites for inhibiting the formation and volatilization of MoO_(3).Additionally,Y cation segregation to oxide grain boundaries further promoted the selective oxidation of Cr and Si to form more protective oxide layer.These beneficial roles of Y essentially eliminated the synergistic effects of MoO_(3) volatilization and lamellar Cr_(2)N precipitation on catastrophic oxidation.Accordingly,the oxidation resistance of Y-bearing S32654 was improved by 22%–45%.展开更多
文摘Due to isothermal heat treatment or welding,duplex stainless undergoes a variety of decomposition processes at a temperature ranging from 300 - 1 100℃,which could form inter-metallic phases likeσ-phase and xphase,as well as Cr2N and M23C6,etc.These processes are not only influenced by temperature and cooling speed, but also are affected by alloy element content.The purpose of the research was to work out the qualitative and quantitative analysis of precipitate phases in 2 205 duplex stainless steel with different isothermal heat treatment situation.After choosing the electrolyte and electrolytic systems,we use electrochemical method to extract precipitate phases from the matrix.Scanning electron microscope（SEM） and X-ray diffraction（XRD） were used to examine their modality and structure.Particle size distribution was performed by dynamic laser scattering sizer （DLS-Sizer）.Furthermore,oxygen-nitrogen analyzer and carbon-sulfur analyzer were applied to measure the content of nitrogen and carbon in precipitate phases.Separation and quantitative analysis of precipitate phases were carried out by wet chemical analysis and inductively coupled plasma spectrometry（ICP）.In a word,combining chemical and physical methods,our research reveals the transformation of precipitate phases’species,content, elemental composition and particle size distribution during different isothermal heat treatment situation.
文摘介绍了10Cr21Mn16NiN钢线材成分设计、增氮原理、冶炼工艺、轧制和固溶工艺、Cr_(2)N相析出的生产工艺。采用30 t AOD精炼,吹氮气增氮,精炼后期加氮化锰。轧制时采用1240℃加热、控轧控冷,保证了盘条表面质量,避免了中心缩孔等问题;固溶温度应控制在1100℃左右,且保温30 min后快冷,可防止Cr_(2)N相析出。成功生产出表面质量和性能优良的10Cr21Mn16NiN不锈钢线材。
基金the National Natural Science Foundation of China(Grant Nos.U1960203 and 51774074)Shanxi Municipal Major Science&Technology Project(Grant No.20181101014)+2 种基金Fundamental Research Funds for the Central Universities(Grant Nos.N172512033 and N2024005-4)Talent Project of Revitalizing Liaoning(XLYC1902046)State Key Laboratory of Metal Material for Marine Equipment and Application(Grant No.HG-SKL(2019)13).
文摘Precipitation behavior of P550 steel for non-magnetic drill collars was investigated by microstructure characterization as well as thermodynamic calculation.The results demonstrate that the main precipitate formed at 650–900℃was cellular Cr_(2)N,and its precipitation depended heavily on the aging temperature.The most sensitive precipitation temperature of cellular Cr_(2)N was 750℃.At 750℃,the cellular Cr_(2)N exhibited fast-slow precipitation kinetics with the aging time prolonging.The initial precipitation of cellular Cr_(2)N was governed by the short-range intergranular diffusion of Cr.During long-term aging,its growth was controlled by the long-range bulk diffusion of Cr.In addition,cellular Cr_(2)N induced the precipitation of r phase ahead of the cell after long period of aging.Increasing the nitrogen content resulted in the increment of both the nucleation site and the driving force for the cellular Cr_(2)N,which jointly promoted its precipitation.
基金the National Natural Science Foundation of China(Nos.U1860204 and 52004061)the Talent Project of Revitalizing Liaoning(No.XLYC1802101)+2 种基金the China Postdoctoral Science Foundation(No.2020M670777)the Northeastern University Postdoctoral Funds(No.20200321)the Fundamental Research Funds for the Central Universities(No.N2125017)。
文摘Aiming at serious catastrophic oxidation problem of super-austenitic stainless steel S32654,the influence of different rare earth elements on its oxidation behavior was comparatively investigated at 1200℃.The mechanism of Y significantly improving high-temperature oxidation resistance of S32654 was unveiled.The results demonstrated that Y played much better beneficial roles than Ce and La in the initial formation of oxide layer:(1)Y promoted Cr segregation to steel surface to combine with O;(2)its preferential oxidation provided nucleation cores for Cr_(2)O_(3).Both roles jointly promoted the selective oxidation of Cr and then the formation of protective Cr-rich oxide layer.This provided good prerequisites for inhibiting the formation and volatilization of MoO_(3).Additionally,Y cation segregation to oxide grain boundaries further promoted the selective oxidation of Cr and Si to form more protective oxide layer.These beneficial roles of Y essentially eliminated the synergistic effects of MoO_(3) volatilization and lamellar Cr_(2)N precipitation on catastrophic oxidation.Accordingly,the oxidation resistance of Y-bearing S32654 was improved by 22%–45%.
