双相不锈钢高温微观变形行为

 利用共聚焦激光扫描高温显微镜(CSLM)等设备对双相不锈钢的高温拉伸变形行为进行了研究,分析了双相不锈钢的热塑性变形机理,得出影响双相不锈钢热塑性的主要因素有：相界结合力、组织形貌和两相力学性能的差异。指出在双相不锈钢热加工时,增强相界结合力、优化组织形貌或减小两相力学性能差异,可有效改善双相不锈钢的热塑性。     

2205双相不锈钢夹杂物控制与研究

2205双相不锈钢是一种性能非常优秀的不锈钢类型,属于第二类不锈钢,耐腐蚀性能较为优秀,一般在海水淡化、核设施等工作环境较为严苛的场所使用。但是其在热处理过程中易产生裂隙,这极大地限制了其应用范围,由此对于2205双相不锈钢夹杂物的控制研究具有重要的现实意义。本文首先阐述了不锈钢的发展历程及其分类,进而表达了不锈钢中的夹杂物的特点和性质,并对其进行了改进措施。然后分析了改进之后的不锈钢中的夹杂物含量和性质。     

奥氏体不锈钢高温变形行为的研究

作者采用“ＴＨＥＲＭＥＣＭＡＳＴＯＲ－Ｚ”热加工模拟试验进行了奥氏体不锈钢高温变形模拟试验，实测了热轧时钢的变形过程中温度，变形速度和应变量对变形抗力的影响。通过试验得到了热变形时钢的真应力－真应变曲线，利用计算机进了试验数据的优化处理，建立了计算热轧和体不锈钢的变形贽数学模型。     

酒钢不锈钢公司成功开发2205双相不锈钢

经过近半年的努力,2011年10月,酒钢不锈钢公司成功生产出200t合格的2205双相热轧酸洗卷。丰富了酒钢不锈钢公司的品种,增强了公司的市场竞争能力。     

2205双相不锈钢表面起皮缺陷分析

对2205双相不锈钢冷轧NO.1板表面起皮缺陷进行扫描电镜和能谱分析,并结合其冶炼-热轧-退火酸洗整个生产工艺,得出:缺陷的实质是热轧过程中咬入氧化铁皮经过退火酸洗后的表现形式。通过对2205双相不锈钢板坯加热后金相组织、热塑性、热轧板金相组织以及热轧板氧化铁皮结构的分析,得出:板坯边部柱状晶的存在以及热轧加热炉加热温度过高会影响材料的热塑性,导致轧制过程边部出现微裂纹,热轧完成后演变为咬入式氧化铁皮缺陷。提高2205双相不锈钢等轴晶率、控制加热温度在1260℃以下可以有效避免起皮缺陷的发生。     

双相不锈钢热塑性的研究

本文采用落锤试验法，研究了在不同试验温度下镍、氮合金元素含量和α／γ两相比例对高铬镍双相不锈钢热塑性的影响。     

双相不锈钢2205热轧钢带氧化铁皮显微分析

 应用OM、SEM、XRD技术,分析研究了双相不锈钢2205热轧钢带氧化铁皮显微结构特征,这是决定钢带酸洗效果的本质因素之一。结果表明：热轧后钢带表面氧化铁皮存在大量的裂纹以及局部伴有氧化铁皮部分脱落,有利于酸洗;氧化铁皮厚度一般为10 μm左右,但是存在局部区域氧化层增厚以及氧化铁皮向基体内部的嵌入;氧化铁皮中含有难以酸洗的铁橄榄石（Fe2SiO4）和尖晶石结构的Cr2O3·FeO等物相,增加了钢带表面氧化铁皮酸洗去除的难度。     

590℃时效处理对2205双相不锈钢组织及硬度的影响

通过对2205双相不锈钢590℃的时效行为进行研究,采用光学显微镜(OM)、环境扫描电镜(ESEM)和透射电镜(TEM),分析时效处理工艺对材料组织的影响规律.发现590℃时效48h,开始有中间相析出,析出相集中在α相以及α/γ相界.通过TEM物相分析,发现590℃时效析出相有R相.此外,还研究了时效处理对材料硬度的影...     

双相不锈钢2205的热加工性能研究

研究了双相不锈钢2205在1 000~1 200℃温度、应变速率0.01~30 s-1下压缩变形的热加工行为。讨论了该条件下的应力应变曲线的特征并根据sinh-Arrhenius方程计算了其形变激活能为519 KJ/mol。通过对试样的金相及TEM观察,讨论了双相不锈钢中的奥氏体相和铁素体相在热变形中的回复、再结晶机制。     

双相不锈钢2205铸态组织的热变形研究

研究了工业连铸双相不锈钢2205在不同温度和应变速率下的热变形过程。通过单道次热模拟压缩试验分析了铸态2205流变应力与温度和应变速率的关系,计算出铸态2205的热变形激活能Q=599 kJ/mol,说明铸态2205热加工性能较差。组织分析显示,两相之间变形不协调是相界微裂纹产生的根本原因。     

双相不锈钢热变形后的静态软化行为及组织分析

在MMS-200热模拟试验机上,采用不同道次压缩法研究了00Cr22Ni5Mo3N双相不锈钢的高温热变形行为,从双道次压缩试验数据中得到不同温度条件下的软化率曲线,并对变形显微组织进行了分析。结果表明：在1~400 s道次间隔时间内,软化率随时间延长而增加,在100 s之内基本完成静态软化。变形温度越高,静态软化行为越...     

2205双相不锈钢板带生产工艺

简述了2205双相不锈钢的基本特性,详细介绍了2205双相不锈钢的轧制、退火及酸洗工艺,给出了2205双相不锈钢生产中的注意事项。     

Investigation of the Hot Plasticity of Duplex Stainless Steel

Hot plasticity of a nitrogen alloyed 25Cr 7Ni-4Mo duplex stainless steel was investigated. The results indicate that the main factors affecting the hot plasticity of duplex stainless steel are listed as follows： coalescent force of phase interface, microstructure, and the phase ratio and difference between the mechanical properties of ferrite and austenite. The heat treatment and sulphur contents have a notable effect on the hot plasticity. The reasonable heat treatments and the increased interfacial coalescent force will effectively enhance the hot plasticity of duplex stainless steel.     

Effects of Sulphate-reducing Bacteria on Corrosion Behaviour of 2205 Duplex Stainless Steel

The effects of sulphate-reducing bacteria(SRB)on the 2205 duplex stainless steel in the sea water and oil industry environments were studied by electrochemical impedance spectroscopy(EIS),potentiodynamic polarization and microorganism analysis.The results showed that the detected SRB was the non-spore bacillus of about 0.8μm×(1.8-2.2)μm in size and the content of S was about 7.59% in the corrosion products.SRB contributed to the corrosion evolution which caused the corrosion failure of 2205 duplex stainless steel pipe in the liquid hydrocarbon cooler.During the corrosion process,the produced H2S could significantly influence the anodic process and finally accelerate the corrosion.SEM observation indicated that the distribution of SRB on the surface of 2205 duplex stainless steel was nonuniform.X-ray photoelectron spectroscopy analysis revealed that the surface film was composed of Cr2O3,MoO3,FeS,FeS2,Fe(OH)2 and FeO after immersing the sample in the SRB medium for 14d.     

Properties of Laser Welded SAF 2205 Duplex Stainless Steel Sheet

High rate welding methods for sheet material can offer significant cost reduction for mass production application in comparison with more conventional arc processes. Therefore, in this research, laser welds in SAF 2205 duplex stainless steel (DSS) sheets welded using different welding speeds were investigated. Metallography, texture measurements and mechanical testing were carried out on the weld joints. The corrosion properties were not evaluated. The base material was characterised by a bamboo‐like morphology and a ferrite volume fraction of 53 %. For all welding speeds, the ferrite level in the weld zone was higher than 85 % and the austenite showed an acicular morphology. Whereas in the base material a clear element partitioning existed between ferrite and austenite, no partitioning was observed in the welded zone. This is due to the very high cooling rates, which limit the amount of diffusion that can take place. Electron backscattering diffraction revealed that the texture of the cold rolled material was destroyed by the welding process. While the hardness of the base material was about 265 HV, the maximal hardness in the fusion zone exceeded 310 HV and increased with an increase of the welding speed. Yield and tensile stength were however not dramatically influenced. On the other hand, the formability properties were deteriorated by an increase of the welding speed. This behaviour can also be observed on the fracture surfaces of tensile specimens. The tensile tests on the welded sheet resulted in ductile fracture surfaces, but an easier void formation was observed in the laser welds. However, it has to be pointed out that formability of the laser welded DSS sheets is acceptable when a lower welding speed is used. This is also confirmed by the crack propagation observed during the Erichsen test. Therefore, the laser welding can be used as a joining operation for DSS sheet materials providing the corrosion requirements are fulfilled.     

Effects of Temperature and Strain Rate on Flow Behavior and Microstructural Evolution of Super Duplex Stainless Steel under Hot Deformation

Hot compression tests were carried out in the temperature range of 1 223-1 473 Kand strain rate range of0.01-30s-1 to investigate the flow behavior and microstructural evolution of super duplex stainless steel 2507(SDSS2507).It is found that most of the flow curves exhibit a characteristic of dynamic recrystallization(DRX)and the flow stress increases with the decrease of temperature and the increase of strain rate.The apparent activation energy Qof SDSS2507 with varying true strain and strain rate is determined.As the strain increases,the value of Qdeclines in different ways with varying strain rate.The microstructural evolution characteristics and the strain partition between the two constituent phases are significantly affected by the Zener-Hollomon parameter(Z).At a lower lnZ,dynamic recovery(DRV)and continuous dynamic recrystallization(CDRX)of the ferrite dominate the softening mechanism during the compression.At this time,steady state deformation takes place at the last stage of deformation.In contrast,a higher lnZ will facilitate the plastic deformation of the austenite and then activate the discontinuous dynamic recrystallization(DDRX)of the austenite,which leads to a continuous decline of the flow stress even at the last deformation stage together with CDRX of the ferrite.