Thermal deformation behavior and microstructure of nuclear austenitic stainless steel

Gleeble-1500D thermal simulation tester was employed in the hot-compression investigation of as-cast nuclear 304 austenitic stainless steel under conditions: deformation temperature 950―1200℃; deformations 30% and 50%; deformation rates 0.01 and 0.1 s?1. The results show that the flow stress decreases with temperature rise under the same strain rate and deformation, that the flow stress increases with deformation under the same temperature and strain rate, and that the flow stress increases with strain rate...     

Microstructural evolution and tensile properties of low-carbon steel with martensitic microstructure during warm deforming and annealing

For preparing large-scale nano-grained and ultrafine-grained steel sheets by warm rolling and annealing,the effects of de- forming temperature on both the flow stress and the microstructure evolution of 09MnNiD steel with lath martensitic microstructure were studied by warm-compression test and transmission electron microscopy(TEM)observation.Thereafter,the steel with the lath martensitic structure was multi-pass warm-rolled and then annealed.TEM results indicate that nano-grained and ultrafine-grained steel sheets are formed by warm rolling at 400℃and annealing at 400-600℃.In comparison with the as-warm-rolled specimen,the tensile strength at room temperature changes a little when the rolled samples are annealed below 450℃,and the tensile strength is greatly lowered as the annealing temperature increases to above 550℃.     

Antibacterial and corrosive properties of copper implanted austenitic stainless steel

Copper ions were implanted into austenitic stainless steel (SS) by metal vapor vacuum arc with a energy of 100 keV and an ions dose range of (0.5-8.0)×1017 cm-2. The Cu-implanted SS was annealed in an Ar atmosphere furnace. Glancing X-ray diffrac-tion (GXRD), transmission electron microscopy (TEM) and Auger electron spectroscopy (AES) were used to reveal the phase compositions, microstructures, and concentration profiles of copper ions in the implanted layer. The results show that the antibacterial property...     

热老化对核级316LN锻造控氮奥氏体不锈钢微观组织及性能的影响

研究了热老化对核级316LN锻造奥氏体不锈钢的位错组态、电阻率及显微硬度的影响规律。结果表明,随着热老化的进行,奥氏体基体中位错密度总体下降,而始于晶界向晶内延伸的扩展位错数量增多且宽度变窄,其中,固溶态的扩展位错宽度约为1．0μm,热老化5000h后约为0．2μm。分析认为,碳原子在晶界及其附近微区的偏聚是引起位错亚结构变化的主要原因：电阻率随热老化时间的延长、检测温度的升高而增大,且热老化5000h后电阻率随温度的增长速率高于固溶态;晶内和晶界处的显微硬度值随热老化的进行均有所升高,二者之间显微硬度的差值逐渐增加。     

含铜高氮无镍奥氏体不锈钢的时效处理工艺

采用00Cr18Mn18Mo2N高氮无镍奥氏体不锈钢作为试验材料,以铜作为其抗菌元素,研究了改性材料的时效处理工艺、显微组织、抗菌性能和耐蚀性.结果表明,含铜的高氮无镍奥氏体不锈钢在700~900℃进行1~24 h时效处理,氮化铬的析出量随着时效温度升高和时效时间延长而增加.该钢经800℃时效处理1 h后可改善细菌黏附状况,但抗菌性能较弱,同时析出的氮化铬会明显损害耐蚀性,时效时间越长,耐蚀性受损越严重.开发铜合金化高氮无镍奥氏体抗菌不锈钢时,应从抗菌性和耐蚀性两方面综合考虑以优化时效处理工艺.     

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...     

Physico-chemical properties and microstructure of hydroxyapatite-316L stainless steel biomaterials

Sintering shrinkage, compressive strength, bending strength, metallurgical morphology, microstructure and chemical composition diffusion of hydroxyapatite-316L stainless steel(HA-316L SS) composites were investiga-ted. The results show that the sintering shrinkage of HA-316L SS composites decreases from 27.38O/6o to 8.87% for cylinder sample or from 27.18% to 8.62% for cuboid sample with decreasing the volume ratio of HA to 316L SS,which leads to higher sintering activity of HA compared with that of 316L SS. The compressive strength of HA-316L SS composites changes just like parabolic curve (245.3→126.3→202.8 MPa) with reducing the volume ratio of HA to 316L SS. Bending strength increases from 86.3MPa to 124. 2 MPa with increasing the content of 316L SS. Furthermore, comprehensive mechanical properties of 1.0：3.0 (volume ratio of HA to 316L SS) composite are optimal with compressive strength and bending strength equal to 202. 8 MPa and 124. 2 MPa, respectively. The microstructure and metallurgical structure vary regularly with the volume ratio of HA to 316L SS. Some chemical reaction takes place at the interface of the composites during sintering.     

高温下不锈钢螺栓的材料性能试验研究

为了给建筑钢结构螺栓连接的抗火性能分析与抗火设计提供依据,对不锈钢螺栓高温下的力学性能进行试验研究,开展了两组不同等级不锈钢螺栓高温下的拉伸试验,得到了不同温度下不锈钢螺栓的全应力-应变曲线。对不锈钢螺栓高温下的弹性模量、屈服强度和极限强度进行分析,将试验结果与不锈钢母材和耐火钢螺栓在高温下力学性能进行了对比,并对比相关规范关于不锈钢母材的推荐值,提出了不锈钢螺栓高温下弹性模量、屈服强度和极限强度的折减模型。研究结果表明：不锈钢螺栓高温下的极限强度折减系数与欧洲规范EC3中对不锈钢母材的推荐值相近,弹性模量折减系数差距较大。温度低于650 ℃时,不锈钢螺栓相比不锈钢母材屈服强度下降更慢;温度在500～900 ℃时,不锈钢螺栓相比耐火钢螺栓强度和弹性模量下降更慢。     

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％.     

钢丝增强AZ91复合材料的力学性能

为了提高AZ91镁合金的力学性能,采用浸入铸造法制备了体积分数为3.3%的不锈钢纤维增强AZ91复合材料,并在相同条件下对AZ91及其复合材料进行了热挤压处理.采用扫描电镜（SEM）和力学性能试验机分别对铸态和挤压态材料的显微组织、断口和拉伸性能进行了研究.结果表明：铸态AZ91及其复合材料的抗拉强度分别为250和240MPa.然而经过挤压后,钢丝增强AZ91镁合金的屈服强度和抗拉强度分别达到了375和428.6MPa,与挤压态AZ91和铸态AZ91复合材料相比,分别提高了50%、20%和57.6%、78.6%.同时挤压态复合材料的塑性变形量也显著提高.     

Effect of tin addition on the microstructure and properties of ferritic stainless steel

This article reports the effects of Sn on the inclusions as well as the mechanical properties and hot workability of ferritic stainless steel. Precipitation phases and inclusions in Sn-bearing ferritic...     

Intergranular corrosion behavior of high nitrogen austenitic stainless steel

The intergranular corrosion (IGC) behavior of high nitrogen austenitic stainless steel(HNSS) sensitization treated at 650-950℃ was investigated by the double loop electrochemical potentiodynamic reactivation(DL-EPR) method.The effects of the electrolytes,scan rate,sensitizing temperature on the susceptibility to IGC of HNSS were examined. The results show that the addition of NaCl is an effective way to improve the formation of the cracking of a passive film in chromium-depleted zones during the reactivation scan. Decreasing the scan rate exhibits an obvious effect on the breakdown of the passive film. A solution with 2 mol/L H2_SO_4+1 mol/L NaCl+0.01 mol/L KSCN is suitable to check the susceptibility to IGC of HNSS at a sensitizing temperature of 650-950℃ at a suitable scan rate of 1.667 mV/s. Chromium depletion of HNSS is attributed to the precipitation of Cr_2N which results in the susceptibility to IGC. The synergistic effect of Mo and N is suggested to play an important role in stabilizing the passive film to prevent the attack of IGC.     

异步轧制对316L不锈钢组织与性能的影响

研究了形变量分别为50％和80％的异步轧制（速比1．28）对316L不锈钢显微组织与性能的影响．结果表明：异步轧制后显微组织中出现大量机械孪晶;样品表面粗糙度显著降低,硬度明显提高．由于粗糙度降低和孪晶界的贡献,在腐蚀介质（c（H2SO4）=0．05mol／L,c（NaCl）=0．5mol／L的水溶液）中,样品表现出良好的耐腐蚀性能．     

奥氏体不锈钢活性屏低温离子渗碳工艺研究

利用活性屏离子热处理技术对奥氏体不锈钢进行低温离子渗碳（ASPC）处理,可以在不锈钢表面形成一层无碳化铬析出的碳的过饱和固溶体（Sc相）。ASPC可以在不降低奥氏体不锈钢耐蚀性能的前提下大幅度提高其表面硬度,并解决了不锈钢直流离子渗碳温度均匀性差、工件存在边缘效应等问题,渗碳试样表面基本可以保持不锈钢原色。通过对活性屏上溅射下来的纳米粒子进行显微分析表明,这些粒子是Fe3C、Fe2C5中性粒子,其在ASPC中起到渗碳载体的作用,ASPC是一个溅射-吸附-脱附的过程。     

Film-induced stress enhancing stress corrosion cracking of austenitic stainless steel

A constant deflection device designed for use within a transmission electron microscopy (TEM) was used to investigate the change in dislocation configuration ahead of a crack tip during stress corrosion cracking (SCO of type 310 austenitic stainless steel in a boiling MgCI2 solution, and the initiation process of stress corrosion microcrack. Results showed that corrosion process during SCC enhanced dislocation emission, multiplication and motion. Microcracks of SCC were initiated when the corrosion-enhanced dislocation emission and motion reached critical state.A passive film formed during corrosion of austenitic stainless steel in the boiling MgCI2 solution generated a tensile stress. During SCC, the additive tensile stress generated at the metal/passive film interface helps enhance dislocation emission and motion.     

轧制及退火工艺对301B不锈弹簧钢力学性能影响分析

针对高硬不锈钢用作弹簧时弹性不足、疲劳寿命短等问题,本文结合现场实际生产,以301B奥氏体不锈钢带为研究对象,通过轧制工艺和热处理工艺优化,对其进行了拉伸试验和硬度测试。结果表明,增加变形率,采用低轧制油温度和低轧制速度的轧制工艺,并在冷轧后进行一次400℃低温去应力退火,可以提高带材强度和硬度。同时也说明,适当的轧制工艺和热处理工艺可以改善不锈弹簧钢带的力学性能,从而提高弹簧的弹性极限和疲劳极限。     

Ratcheting boundary of 316LN austenitic stainless steel under thermal aging

Science China Technological Sciences - Previous studies, including ASME and RCC-MR standards, did not consider the influence of environmental factors on the ratcheting boundary of the material, and...     

Q235钢CSP过程组织及性能的转变

对包钢CSP线生产的Q235钢连铸坯及不同道次轧制后空冷的试样进行了组织观察,测定了硬度及力学性能.分析了CSP线生产的Q235钢组织、性能变化的原因.研究表明,随轧制道次的增加,变形后轧件的室温组织细化;沿铁素体晶界分布的珠光体变得均匀、弥散;力学性能较采用传统工艺制备的Q235钢有显著提高.     

退火温度对冷轧304不锈钢带力学性能和残余应力的影响

为得到退火温度对冷轧304不锈钢板形及力学性能的影响,利用拉伸机对不同退火温度下带的力学性能进行了测定,采用盲孔法对钢带表面残余应力进行了测定,得到了退火温度对钢带力学性能和残余应力的影响规律.试验结果表明,随着退火温度的升高,屈服强度和抗拉强度先升高后下降,当退火温度为500℃,退火张力在9 kgf/mm2时,304不锈钢带的屈服强度和抗拉强度最大;且在该温度下残余应力分布最均匀,说明304不锈钢在500 ℃退火时力学性能最佳且板形最好.