氮对新型无镍高氮奥氏体不锈钢塑性流变行为的影响

利用Ludw igson模型研究了两种氮含量不同的无镍奥氏体不锈钢18Cr-12Mn-0.55N（质量分数/%）和18Cr-18Mn-0.63N在室温快速拉伸时的塑性流变行为.结果表明,由于N含量的增大,实验钢18Cr-18Mn-0.63N的加工硬化能力明显强于实验钢18Cr-12Mn-0.55N.N促进CrMnN奥氏体不锈钢中的短程有序,使位错在更高的应变水平进行单系滑移和平面滑移,推迟位错的多系滑移和交滑移,因而提高CrMnN奥氏体不锈钢的加工硬化能力.     

Microstructural evolution and mechanical properties of aging high nitrogen austenitic stainless steels

The microstructural evolution of 18Cr18Mn2Mo0.77N high nitrogen austenitic stainless steel in aging treatment was investigated by optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results show that hexagonal intergranular and cellular Cr2N with a=0.478 nm and c=0.444 nm and body-centered cubic intermetallic χ phase with a=0.892 nm precipitate gradually in the isothermal aging treatment. The matrix nitrogen depletion due to the intergranular Cr2N pre...     

Preparation of high nitrogen and nickel-free austenitic stainless steel by powder injection molding

High nitrogen and nickel-free austenitic stainless steel has received much recognition worldwide because it can solve the problem of "nickel-allergy" and has outstanding mechanical and physical properties. In this article, 0Cr17Mn11Mo3N was prepared by powder injection molding (PIM) technique accompanied with solid-nitriding. The results show that the critical solid loading can achieve up to 64vol% by use of gas-atomized powders with the average size of 17.4 μm. The optimized sintering conditions are de-termined to be 1300°C, 2 h in flowing nitrogen atmosphere, at which the relative density reaches to 99% and the N content is as high as 0.78wt%. After solution annealing at 1150°C for 90 min and water quench, the 0.2% yield strength, ultimate tensile strength (UTS), elongation, reduction in area, and hardness can reach as high as 580 MPa, 885 MPa, 26.0%, 29.1%, and Hv 222, respectively.     

Effects of Ta addition on the microstructure and mechanical properties of Ti40Zr25Ni8Cu9Be18 amorphous alloy

The effects of Ta addition on the microstructure and mechanical properties of Ti₄₀Zr₂₅Ni₈Cu₉Be₁₈ bulk amorphous alloy were investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM), scan electron microscopy (SEM) and compressive testing. As a result, the addition of Ta (0-8at%) prompted the successive precipitation of quasicrystalline phase, CuTi₂ phase and bcc β-Ti solid solution. Additionally, the addition of less Ta content (3at%-5at%) led to the formation of amorphous matrix/nanoquasicrystal/CuTi₂ complex phase structure; and nanoquasicrystals, as reinforcement precipitates, improved the fracture strength of Ti-Zr-Ni-Cu-Be-Ta alloys, which led to the high compressive fracture strength 1856 MPa of Ta5 alloy. With increasing Ta content (5at%-8at%), although the ductile dendritic β-Ti solid solution was precipitated, the strength and plasticity decreased to a great extent resulting from the growth of quasicrystalline phase and CuTi₂ phase.     

Fabrication of high nitrogen austenitic stainless steels with excellent mechanical and pitting corrosion properties

A series of high nitrogen austenitic stainless steels were successfully developed with a pressurized electroslag remelting furnace. Nitride additives and deoxidizer were packed into the stainless steel pipes, and then the stainless steel pipes were welded on the surface of an electrode with low nitrogen content to prepare a compound electrode. Using Si3N4 as a nitrogen alloying source, the silicon contents in the ingots were prone to be out of the specification range, the electric current fluctuated greatly...     

Application of empirical electron theory of solids and molecules to composition design of multi-component medium-low-alloy steels

For austenitic octahedral segregation structure units, their pure mathematics statistic distributive probability is calculated by the empirical electron theory (EET) of solids and molecules and K-B formula. The practical distributive probability can be obtained only if the statistic distribution of austenitic octahedral segregation structure units and the interaction of the alloying elements in steel are considered. Based on 8 groups of experimental data of original steels, three empirical formulas revealing relationships between material macromechanics factor (Sm) and tensile strength (σb), or impact energy (AK), or hardness (HRC) of multi-component medium-low-alloy steels were established, respectively. Through the three empirical formulas, new supersaturated carburizing steel has been successfully designed and developed. The other 2 groups of the original experimental steels are used as the standard steel for testing the percentage error of the new steel. The results show that the calculated values are well consistent with those of measured ones and the new supersaturated carburized steel can meet the requirements of the die assembly of cold-drawn seamless stainless steel tube of Taiyuan Iron & Steel (Group) Company LTD.     

Pitting corrosion and crevice corrosion behaviors of high nitrogen austenitic stainless steels

Pitting corrosion and crevice corrosion behaviors of high nitrogen austenitic stainless steels(HNSS) were investigated by electrochemical and immersion testing methods in chloride solution,respectively.The chemical constitution and composition in the depth of passive films formed on HNSS were analyzed by X-ray photoelectron spectrum(XPS).HNSS has excellent pitting and crevice corrosion resistance compared to 316L stainless steel.With increasing the nitrogen content in steels,pitting potentials and critical ...     

氮含量和环境温度对316L不锈钢耐腐蚀性的影响

研究低温条件下腐蚀溶液温度以及钢中氮含量对316L奥氏体不锈钢耐腐蚀性能的影响,在1mol／L H2SO4＋0．5mol／L NaCl的腐蚀液中,对氮含量为0．0095％～0．5575％的316L奥氏体不锈钢进行阳极极化曲线及电化学阻抗测量。结果表明,提高氮含量,316L奥氏体不锈钢耐蚀性增强;腐蚀液温度升高,316L奥氏体不锈钢耐蚀性减弱。     

镍对07Cr17Ni12Mo2N奥氏体不锈钢组织和高温拉伸性能的影响

利用Gleeble-1500D热模拟机对07Cr17Ni12Mo2N奥氏体不锈钢试样分别在950,1000,1 050,1 100℃以0.05 s-1的应变速率进行了高温拉伸试验,通过分析试验钢组织、断面收缩率曲线、抗拉强度曲线、断口形貌,研究镍对试验钢高温拉伸性能的影响.结果表明：降镍后试验钢仍为单一的奥氏体组织;热塑性有所降低,断面收缩率平均下降了18.87％;抗拉强度平均提高了12.39％.     

双相不锈钢表面奥氏体高氮层的制备技术

高温渗氮是在奥氏体/铁素体双相不锈钢表面形成奥氏体高氮层的一种有效方法.为了获得氮含量高、组织均匀且适合于后续加工的表面高氮不锈钢层，必须确定合理的高温渗氮工艺.通过优化高温渗氮工艺参数，研究了双相不锈钢高温渗氮过程中加热温度、保温时间、氮气压力等对渗氮效果的影响.结果表明，通过高温高压渗氮可使不锈钢表面形成高氮氮化层，可使双相不锈钢通过渗氮发生表面奥氏体转变，获得组织梯度变化的多相复合不锈钢材料.     

真空热轧不锈钢复合板界面结合行为的研究

为了研究真空热轧不锈钢复合板的结合行为,本文以热轧304不锈钢／Q345低碳钢复合板为研究对象,通过剪切试验及组织分析等手段研究了变形量及真空度对不锈钢复合板结合性能的影响规律．结果表明,轧制总变形量从35％增加到75％之后复合板的剪切强度大约可增加100MPa．真空度降低会导致结合界面氧化程度增加,进而降低复合板的结合性能,当真空由0.1Pa变为20Pa时,界面氧化物的比例由约10％提高到约50％,剪切强度由440MPa降低到了350MPa左右．最后根据试验结果提出了热轧不锈钢复合板的结合行为．     

Lamella Multiple Grained Structure Making 2205 Duplex Stainless Steel with Superior Strength and Ductility

We demonstrate a 2205 duplex stainless steel (DSS) synthesized by aluminothermic reaction and followed two-step rolling which had a superior yield strength of 863 MPa,ultimate tensile strength of1 103 MPa and an elongation of 21% at room temperature.The phase,grain size and distribution of the steel were characterized by optical microscope,X-ray diffraction,electron back-scatter diffraction and transmission electron microscope.The results show that the steel consists of lamellar ferrite and austenitic phase with multiple grain size distribution from nanoscale to microscale.The high strength is attributed to strengthening of high back stress arising from laminated dual-phase heterogeneous ultrafine grained structure and distribution.The high ductility originates from back-stress hardening and dislocation hardening.     

Bonding mechanism of X10CrNi18-8 with Ni/Al_2O_3 composite ceramic by pressureless infiltration

An alloy steel/alumina composite was successfully fabricated by pressureless infiltration of X10CrNi18-8 steel melt on 30%(mass fraction) Ni-containing alumina based composite ceramic(Ni/Al2O3) at 1 600 ℃.The infiltration quality and interfacial bonding behavior were investigated by SEM,EDS,XRD and tensile tests.The results show that there is an obvious interfacial reaction layer between the alloying steel and the Ni/Al2O3 composite ceramic.The interfacial reactive products are(FexAly)3O4 intermetallic phas...     

三种不锈钢在含Cl^—衣康酸介质中的腐蚀行为

研究了３种不锈钢在衣康酸／氯化钠水溶液中的腐蚀和电化学特性并探讨了介质组成和温度的影响。结果表明,在一定范围内,随衣康酸浓度,氯化钠浓度和温芳的提高,不锈钢的腐蚀速率、致钝电流密度和维钝电流密度也有所增大,不锈钢的点蚀电位与衣康酸介质中Ｃｌ＾－浓度的对数间存在线性关系;     

低温氮化316奥氏体不锈钢在H2S环境下的静态腐蚀行为

为研究低温液体氮化奥氏体不锈钢在H₂S环境下的静态腐蚀机理,在430 ℃对316奥氏体不锈钢低温液体氮化8 h。模拟H₂S腐蚀环境,通过X射线衍射分析仪(XRD)、扫描电子显微镜(SEM)、分析天平、EPMA电子探针、X射线光电子能谱衍射仪研究低温液体氮化对奥氏体不锈钢在H₂S腐蚀环境下的静态腐蚀行为。结果表明,在静态腐蚀条件下,低温氮化后奥氏体不锈钢表面形成的含氮过饱和扩展奥氏体层(S-相)能够有效地阻止腐蚀介质向材料基体浸入,使得材料的腐蚀失重下降了34%,减缓了材料的腐蚀程度,显著提高了材料的表面性能。     

Z3CN20-09M铸造不锈钢的热老化机理研究

为了研究Z3CN20-09M铸造不锈钢长期服役后的热老化机理,采用硬度法和透射电子显微分析法研究了国产Z3CN20-09M铸造不锈钢在400℃加速老化1×104h后的性能和组织变化.试验结果表明：与原始态相比,热老化1×104h后Z3CN20-09M钢的洛氏硬度上升了21.37%,同时由于铁素体内调幅分解形成的富Cr的α′相和富Fe的α″以及奥氏体相内的析出物导致铁素体相和奥氏体相的显微硬度分别上升了70.81%和25.15%.调幅分解所引起的铁素体脆化是材料脆性增大的主要原因.     

Thermal shock resistances of FeMnCr/Cr<Subscript>3</Subscript>C<Subscript>2</Subscript> coatings deposited by arc spraying

Arc spraying with the cored wires was applied to deposit FeMnCr/Cr₃C₂ coatings on low carbon steel substrates, namely FM1, FM2 and FM3. Thermal shock resistances of the coatings were investigated to assess the influence of Cr₃C₂ content on thermal shock resistance. Characteristics of the coatings under thermal cycling test were studied by optical microscopy, field emission scanning electron microscope (FE-SEM) and energy dispersion spectrum (EDS), X-ray diffraction (XRD). The experimental results show that hardness of the coatings increases, bonding strength decreases slightly with increase of the Cr₃C₂ content of the coatings. As a result, FM2 coating possesses the best thermal shock resistance, attributing to its better thermal expansion matches and wettability than those of FM3 coating, less oxide rate than that of FM1 coating restraining from cracks formation and propagation in coatings.     

18—8不锈钢钝化膜的光电化学研究

本文研究了18—8不锈钢钝化膜在硼酸/硼酸钠溶液中的光电化学特性,并和相同条件F纯铁、铬、镍以及铁铬合金钝化膜的光电化学行为进行了比较。结果指出,不锈钢钝化膜主要由Cr_2O_3和Fe_2O_3的固溶体组成,并具有非晶态n型半导体特性。其平带电位为-0.30V(SCE),禁带宽度为2.1eV。     

温度、应变率和晶粒对Mn18Cr18N钢高温塑性的影响

通过拉伸热模拟试验研究了温度、应变率和晶粒尺寸对Mn18Cr18N高氮奥氏体不锈钢高温塑性的影响。结果表明：在800℃~1 200℃温度范围内,Mn18Cr18N高氮奥氏体不锈钢的塑性随温度升高而升高,1 200℃时达到最好,然后开始下降;应变率通过再结晶的作用而影响塑性;当温度低于1100℃时,细晶粒尺寸材料的塑性优于粗晶粒尺寸,而温度高于1 100℃时中等晶粒尺寸材料塑性最好。     

Microstructure and mechanical properties of FGBA/BG air cooling bainitic steels containing niobium

The effect of different Nb additions on the mechanical properties and microstructure evolution of grain boundary allotriomorphic ferrite(F_(GBA)) / granular bainite(B_G) air cooling bainitic steels was investigated.The results indicate that the tensile strength and yield strength increase by 157 and 97 MPa,respectively with the addition of 0.02wt%Nb.The steel acquires superior strength and toughness with the addition of 0.06wt%Nb.The results of scanning electron microscopy and transmission electron micro...