低镍不锈钢激光-电弧复合焊接头组织性能研究

低镍含氮奥氏体不锈钢强度高,韧性佳,在化工装备及建筑装饰等领域广泛应用。为揭示保护气体对低镍含氮奥氏体不锈钢焊接接头微观组织和力学性能的影响机制,分别采用92%Ar+8%N2与95%Ar+5%CO2两种混合比例的保护气体对08Cr19Mn6Ni3Cu2N低镍含氮奥氏体不锈钢进行了激光-MAG电弧复合焊。研究表明：氮气的加入使焊接接头平均显微硬度有所下降;电弧收缩明显,焊接飞溅增加且体积增大,电弧稳定性变差;焊缝中奥氏体含量增加约20%,而铁素体枝晶变细,二次枝晶臂变短。焊缝组织中未发现σ相及氮化物析出;从四个晶面观察奥氏体晶粒尺寸也是由于氮气的加入而减小;焊接接头拉伸性能略微下降,但耐腐蚀性能提高。     

拉伸变形对高氮奥氏体不锈钢显微组织和耐腐蚀性能的影响

对高氮奥氏体不锈钢QN1803和常规奥氏体不锈钢304进行了不同形变量的拉伸实验,通过EBSD、XRD和TEM分析了其形变组织和强韧化机制.采用电化学工作站、酸性介质腐蚀实验和OM、SEM分析了不同拉伸形变量下的耐腐蚀性能和腐蚀机理.随着拉伸形变量的增加,QN1803和304不锈钢的微观组织均出现由位错塞积到α马氏体的...     

高强度含N节Ni奥氏体不锈钢08Cr19Mn6Ni3Cu2N (QN1803)的显微组织及性能

借助Thermo-Calc热力学相图计算软件,设计了可用于替代06Cr19Ni10 (S30408)的高强度含N节Ni奥氏体不锈钢08Cr19Mn6Ni3Cu2N (QN1803),通过OM、SEM和电化学工作站等方法研究了其组织及性能。结果表明,当固溶温度从1040℃升至1120℃时,QN1803钢的晶粒尺寸均小于S30408,两者平均晶粒尺寸之差由1.8μm提高至16.27μm。N原子起到细晶和固溶强化的作用,使QN1803钢的屈服强度提高至400 MPa以上,达到S30408钢的1.3倍;N原子降低了奥氏体不锈钢的低温韧性,使QN1803钢在-60℃以下的冲击功显著低于S30408钢。经600～900℃敏化处理后,QN1803钢沿晶界析出富Cr的碳化物,析出的鼻尖温度为800℃;由于N原子抑制碳化物的形核和长大,QN1803钢发生晶间腐蚀需要更长的敏化时间,在700℃敏化处理时,QN1803钢发生晶间腐蚀所需要的时效时间是S30408钢的2倍。与S30408钢相比,QN1803钢钝化膜的N和Cr元素含量更高;QN1803钢属于稳态奥氏体不锈钢,具有与S30408钢相近的点蚀速率(4.72 g/(m~2·h))和更高的点蚀电位(327 mV);经60%冷轧压下变形后,QN1803钢的耐点蚀能力是S30408钢的1.15倍,制品应力开裂风险更低。由于添加了1.65%的Cu元素,使QN1803钢在5%H_2SO_4腐蚀溶液中,表面可生成一层保护基体的富铜膜,从而使其在稀H_2SO_4溶液中的耐腐蚀能力达到S30408钢的6.6倍。     

低镍和无镍奥氏体不锈钢的研究现状及进展

低镍和无镍奥氏体不锈钢以锰、氮等元素取代Cr-Ni不锈钢中的镍元素而具有较低的成本、优异的综合性能.综述了以锰代镍的Cr-Mn不锈钢,低镍Cr-Mn-Ni-N不锈钢,高氮无镍的Cr-Mn-N不锈钢及其在生物医用领域的研究和应用进展,并对低镍和无镍奥氏体不锈钢的发展进行了展望.     

含氮奥氏体不锈钢在焊管领域中的应用前景

传统的304、316等奥氏体不锈钢焊管的焊缝很难保持全奥氏体组织状态,而含氮Cr-Ni奥氏体不锈钢既具有高奥氏体稳定性及由此带来的优良塑性、韧性和加工性能,又具有高强度及高耐腐蚀性,将是应用前景更为广泛的不锈钢焊管新品种。详细介绍了含氮奥氏体不锈钢的发展情况、氮在其中所起的作用、焊接特性及其在焊管生产上的应用,并对国内不锈钢及其焊管生产提出了建议。     

1Cr17Mn6Ni5N等离子弧焊接头的组织分析

采用等离子弧焊接方法对1Cr17Mn6Ni5N进行了焊接试验,并用金相、扫描电镜(SEM)分析了奥氏体不锈钢焊缝、热影响区显微组织的变化,最后用显微硬度计测试了接头的显微硬度,特别是对焊缝中δ-铁素体、马氏体和碳化物等的含量和分布形态进行了研究,为焊接生产中含氮奥氏体不锈钢焊接提供了试验依据.     

填充金属对08Cr19MnNi3Cu2N低镍含氮奥氏体不锈钢MAG焊接头组织性能的影响

采用熔化极活性气体保护焊(MAG焊)工艺,对2. 8 mm厚08Cr19MnNi3Cu2N低镍含氮奥氏体不锈钢试板进行焊接。选取ER308L和ER307Si两种焊丝,借助光学显微镜、力学性能测试及晶间腐蚀等分析方法,对焊接接头组织和性能进行系统评价和分析。结果表明:两种焊丝获得焊缝组织均为奥氏体+δ-铁素体,且奥氏体含量均在91%以上;ER307Si焊丝的焊接接头γ-固溶体含量较高,但是焊缝区域硬度略低;Ni元素含量的降低使得两种接头的抗点蚀能力下降,但抗晶间腐蚀性能表现优异。     

奥氏体不锈钢焊缝中的δ—铁素体特征

该文通过金相、Ｘ－射线衍射、扫描电镜（ＳＥＭ）和电子探针（ＥＰＭＡ）等实验方法，研究了铬－镍奥氏体不锈钢（１８－８）焊缝中的δ－铁素体形态，分析了δ－铁素体的形成和焊缝中铬、镍、钼等合金元素对δ－铁素体的影响，以期在实验基础上对铬－镍奥氏体不锈钢的焊接生产提供指导。     

厚板奥氏体不锈钢焊接技术研究现状

随着厚板奥氏体不锈钢应用的日益广泛,厚板奥氏体不锈钢焊接技术受到越来越多的关注。结合厚板奥氏体不锈钢的焊接性,对厚板奥氏体不锈钢焊接技术的研究成果及发展现状进行了详细分析,重点介绍了常规电弧焊、埋弧焊、窄间隙焊、电子束焊接和激光焊在焊接厚板奥氏体不锈钢时的研究情况,包括焊接工艺制定、焊材选择、焊接参数选取及焊接质量评价等,并提出了目前厚板奥氏体不锈钢焊接存在的问题及今后的发展方向,对厚板奥氏体不锈钢焊接技术的未来发展具有重要意义。     

18-8型奥氏体不锈钢焊接热裂纹的分析

正0前言18-8型奥氏体不锈钢,包括在其基础上增加Cr、Ni含量并加入Mo、Cu、Si、Nb、Ti等元素发展起来的高CrNi系列钢,铬、镍含量分别约为19%和10%,在氧化性介质中耐蚀性优良,在工业生产中应用量逐年递增,其在不锈钢的使用中占据主体地位,但焊接时易出现焊接热裂纹。1奥氏体不锈钢焊接热裂纹1.1结晶裂纹奥氏体不锈钢含镍量较高,液、固相线的温度区间较大,焊缝结晶时间较长,且单相奥氏体结晶方向性强,所以杂质偏析比较严重,易产生结晶热裂纹。这是     

Mo-Si-B系材料的性能及制备

综述了Mo-Si-B系材料的研究进展。主要就材料在各种环境中的氧化性能、单相和多相材料的力学性能、材料的电学性能和热学性能等方面的研究进展进行了介绍。通过无压烧结方法,在1600℃合成了7种不同原料配比的Mo-Si-B系材料。用X射线衍射仪分析了材料的物相组成,确定了最佳的B与Si的原子比为0．865。但是无压烧结法得到的材料致密度不够,还需要对合成工艺作进一步的研究。     

Elastic and optical properties of zinc-blende CrSb and its effective mass

The elastic, optical, and effective mass properties of CrSb in zinc-blende（ZB） phase were investigated.The calculations were carried out using the full-potential linearized augmented plane wave plus local orbital according to the density functional theory. The results of elastic calculations by generalized gradient approximation and local density approximation approximations indicate that ZB CrSb is a ductile material and its Debye temperature is rather low. Band structure and density of state calculations introduce the ZB CrSb as a half-metal with spin polarization of100 %. In metal state, 16 th and 17 th bands cut off the Fermi level. Calculations study the effective mass, Fermi velocity,and Fermi surface at 16 th and 17 th bands. In continue,optical quantities such as dielectric function, energy loss function, and optical conductivity were investigated.     

Sn改性Ti-Zr-Cu-Ni钎料的微观组织和力学性能

采用自制Ti-Zr-Cu-Ni-Sn钎料钎焊TA2钛合金,研究了不同Sn元素含量改性Ti-Zr-Cu-Ni钎料的熔化特性、微观组织及物相、润湿及熔蚀性、接头拉伸强度。研究表明,Sn含量增加,Ti-Zr-Cu-Ni-Sn钎料固、液相线温度基本升高,但温度差值基本变窄,可更好地抑制钎焊界面脆性化合物形成。Ti-Zr-Cu-Ni-5Sn钎料组织由Ti、Zr基体和晶体相构成,Sn倾向与Ti、Zr结合形成Ti₂Sn₃、Ti₆Sn₅、Zr₅Sn₃等低熔点共晶相。Sn≤1.5%时,随Sn含量增加,钎料对TA2钛合金的润湿性逐渐变差;继续增加Sn,钎料润湿性改善,添加5%Sn的钎料对基体润湿最佳。添加5%Sn并降低Cu、Ni总量的改性钎料对TA2钛合金熔蚀减弱。相同钎焊工艺下,添加5%Sn接头的强度和塑性均有提升。钎焊温度升高,Ti-Zr-Cu-Ni钎料产生更多强化物相,致接头强度大幅提升,而Ti-Zr-Cu-Ni-5Sn钎料产生的含Sn物相强化作用对接头强度提升有限;相...     

Structural and optical characterizations of pyronine B thin films and its photovoltaic applications

In this work, the organic thin films of pyronine B (PYR.B) were deposited by thermal evaporation technique under high vacuum (∼10⁴ Pa). The crystal structure, examined by X-ray powder diffraction, indicates that the films are single phase with strong preferred (4 0 0) orientation. Scanning electron micrographs of the films indicate a clearly almost uniform distribution with large grain sizes in the range 5-10 μm. The molecular structure and electronic transitions of PYR.B were investigated by Fourier-transform infrared (FTIR). Fluorescence characteristic of PYR.B at room temperature (300 K) exhibits visible band peak located at 569.65 nm. The color parameters were extracted from the reflectance spectrum of PYR.B. The optical constants such as refractive and extinction indices were determined from the measured transmittance and reflectance spectra using the spectrophotometric method. The dependence of absorption coefficient on the photon energy was determined and the analysis of the result showed that the optical transition in PYR.B is allowed and direct. The current density-voltage (J-V) characteristics in dark show the rectification effect due to the formation of Schottky barrier at Al/PYR.B interface. The photovoltaic parameters were calculated from the J-V characteristics under illumination through ITO and discussed in detail.     

Effect of sintering temperature and composition on microstructure and properties of PMS-PZT ceramics

The piezoelectric ceramics xPb（Mn1/3Sb2/3）O3-（1-x）Pb（Zr1/2Ti1/2）O3 （abbreviated as PMS-PZT） were synthesized by traditional ceramics process. The effect of sintering temperature and the amount of Pb（Mn1/3Sb2/3）O3 （abbreviated as PMS） on phase structure, microstructure, piezoelectric and dielectric properties of PMS-PZT ceramics was investigated. The results show that the pure perovskite phase is in all ceramics specimens, the phase structure of PMS-PZT ceramics changes from tetragonal phase to single rhombohedral phase with the increasing amount of PMS. The dielectric constant εr, Curie temperature Tc, electromechanical coupling factor kp and piezoelectric constant d33 decrease, whereas the mechanical quality factor Qm and dielectric loss tanδ increase with the increasing amount of PMS in system. The optimum sintering temperature is 1 200-1 250 ℃. It is concluded that the PMS-PZT （x=0.07） ceramics sintered at 1 250 ℃ is suitable for high-power piezoelectric transformer. These properties include εr=674.8, tanδ =0.005 25, kp=0.658, Qm= 1 520, d33=230 pC/N, Tc=275 ℃.     

Fe-Co软磁合金磁性能及机械性能的研究

Fe-Co合金是重要的软磁材料,应用广泛.本文综述了化学成分、合金元素、有序度、晶粒尺寸、磁场、杂质和应力对其磁性能和机械性能的影响.并分析了Fe-Co合金的应用前景和发展趋势.     

FeCuNbSiB非晶纳米晶带材软磁性能和压磁性能研究

本文主要研究了Fe73.5Cu1Nb3Si13.5B9纳米晶带材在不同的热处理工艺和压应力条件下的软磁性能变化情况.结果表明:带材在550℃×1h热处理工艺时将晶化成纳米晶材料,此时带材软磁性能最好;纳米晶带材的|μ|,受压应力影响大,尤其是在小于0.2MPa压应力作用下,软磁性能变化非常敏感,|μ|随压力增加而迅速下降;带材Q值在小于0.2MPa压应力作用下变化非常敏感,Q值随压力增加而迅速下降.当压应力大于0.2MPa时,Q值随压应力变化不明显,压应力不影响带材Q值随频率的变化规律.     

层压复合材料的工艺性能及使用性能

层压复合材料是由若干层薄金属板与粘弹性树脂通过胶接固化而形成的一种特殊的复合材料,是近几年在国外迅速发展的一种新材料.主要研究和讨论层压复合材料的减振性能、成形性能、耐久性能和焊接性能等工艺性能以及其使用性能,重点分析了其减振性能和成形性能,并在此研究基础上,提出了此种复合材料今后研究的内容和方向.     

Synthesis and thermoelectric properties of the quaternary type-I Si clathrates K8-δGaxAlySi46-x-y

The effects of substituting Ga atoms with Al on the thermoelectric properties of the ternary Si clathrate K₈Ga₈Si₃₈ were assessed over the temperature range of 10–700 K. For this purpose, the series of quaternary Si clathrates K_8-δGa_xAl_ySi_46-x-y (x + y ≈ 8; 0 ≤ y < 8) was synthesized by heating mixtures of K, Ga, Al and Si at temperatures between 1223 and 1353 K. The lattice constant of K_8-δGa_xSi_46-x was found to increase with the Al content, y, and Al substitution also significantly changed the transport properties of the clathrate, even though Al and Ga are isovalent. Electrical resistivity measurements showed that the conduction mechanism changed from variable range hopping conduction to metallic conduction with increasing y. The Seebeck coefficient, S, was negative for all of the samples, indicating that the dominant carriers were electrons, while the absolute value of S decreased with y. All specimens had approximately the same value of thermal conductivity, κ, on the order of 1.4 W/Km at 300 K, except for K_7.7Al_7.5Si_38.8. K_7.5Ga_4.8Al_3.0Si_38.7 exhibited the largest power factor, and therefore the highest thermoelectric dimensionless figure of merit, ZT, with a value of 0.066 at 550 K. This value is approximately six times that of the ternary Si clathrate K_7.4Ga_7.7Si_38.9.     

Effect of chromium additions on the mechanical and physical properties and microstructure of Fe-Co-Ni-Cr-Mo-C ultra-high strength steel: Part I

The effect of chromium additions to an Fe-14Co-10Ni-0.1Mo-0.16C (AF1410 based) secondary hardening steel was evaluated by mechanical and physical properties and by microstructural examination. This unique behavior was extended to encompass a large range of aging temperatures and times that may be encountered during commercial thermal treatment and/or welding. In the aging range of 482 to 550 °C, an increase in chromium from 2 to 3% in the AF1410 based steel resulted in a substantial strength decrease concomitant with an increase in toughness. This behavior is related to a peak hardening shift, early M₂C carbide coarsening, and an increase in reverted austenite for the 1 wt% Cr increase. The increased aging kinetics resulting from the 3Cr steel caused a faster dissolution of Fe₃C and rapid changes in chromium partitioning in the (Mo,Cr)₂C carbide resulting in a coherency loss with a corresponding decrease in lattice parameter. The kinetics of the secondary hardening reaction, for the two steels, was determined by resistivity data for changes in aging parameters (time/temperature).