LNG用镍基合金焊条熔敷金属的组织与性能

目前国产LNG用镍基低温焊条存在的主要问题是无法同时满足强韧性要求。采用金相显微镜和扫描电镜对自主生产的3种ENiCrMo-6焊条熔敷金属的显微组织进行观察,应用硬度、冲击和拉伸试验对接头力学性能进行测试分析。结果表明:焊缝金属主要由奥氏体以及析出物构成,晶界间存在的低熔点共晶物,易形成沿晶裂纹,降低熔敷金属的拉伸、冲击和弯曲性能。随着合金含量的升高,强度和硬度总体呈上升趋势,对塑性和韧性有所损害,Nb的碳化物析出对裂纹扩展具有阻碍作用,有利于提高韧性。新研制的镍基焊条满足LNG设备对焊缝金属的性能要求。     

La/CeO_2对熔敷金属组织与力学性能的影响

基于现有钛铁矿型电焊条(E4301)抗裂性较差的问题,在新型E4301焊条药皮配方开发研制中采取药皮过渡适量的镧(La)及氧化铈(CeO2)。通过冲击韧度、拉伸、硬度、金相等试验,分析研究La/CeO2对钛铁矿型焊条熔敷金属组织和力学性能的影响。研究结果表明:加入适量的La/CeO2能够细化熔敷金属显微组织,提高熔敷金属的冲击韧度。当药皮中过渡La为0.5%,CeO2为0.1%时,熔敷金属综合力学性能最好。和现有E4301型焊条相比,保持了原焊条优良的焊接工艺性能,而且冲击功提高了50%~54.4%,延伸率提高了20%~25.1%,抗拉强度提高了3.3%~6.3%,屈服强度提高了6.4%~9.2%,性价比高。     

稀土对焊条工艺性和熔敷金属组织性能的影响

本文通过焊条药皮过渡微量稀土的方法，全面研究了稀土对焊条工艺性、熔敷金属中夹渣的分布与形态和熔敷金属组织与性能的影响，为进一步推广和应用稀土焊条得出了有益的实验依据。     

稀土氧化物对焊缝金属抗高温氧化腐蚀性能的影响

本文通过在焊条药皮中分别添加微量稀土氧化物Ｌａ２Ｏ３及ＣｅＯ２,研究其对焊条熔敷金属在空气中和含硫气氛中抗高温氧化及腐蚀性能的影响。结果表明：微量稀土氧化物在焊条药皮中的加入,对其熔敷金属抗高温氧化性能有所提高,对在含硫气氛中的抗高温腐蚀性能有显著提高,添加Ｌａ２Ｏ３的焊条熔敷金属比添加ＣｅＯ２的焊条具有更好的抗高温硫腐蚀性能。     

稀土氧化物对熔敷金属热塑性的影响

研究了焊条药皮中添加稀土氧化物对熔敷金属热塑性的影响，结果表明，稀土氧化物能提高熔敷金属的伸长率和断面收缩率，并细化一次结晶组织，使一次结晶组织的方向性明显减弱，促进等轴晶的发展。     

高锰钢表面激光熔覆Fe-WC复合涂层的组织与性能

采用激光熔覆技术在高锰钢基体上制备了不同WC含量的Fe-WC复合熔覆层,研究了WC添加量对熔覆层组织和性能的影响.试验结果表明,不同WC含量的Fe-WC熔覆层均含有马氏体、M7C3碳化物和未熔WC颗粒,当加入20wt.％的WC时,熔覆层中出现了残余奥氏体,共晶碳化物呈鱼骨状沿晶界析出.Fe-WC熔覆层的硬度和耐磨性随着...     

铌对9%Ni钢用镍基焊条熔敷金属组织和性能的影响

研制9%Ni钢用镍基焊条的难点在于满足熔敷金属强度和塑性指标的前提下提高其低温韧性.在力学性能分析的基础上,采用彩色金相分析、扫描电镜及能谱分析、X射线衍射分析技术研究了铌对9%Ni钢用镍基焊条熔敷金属组织和性能的影响.试验结果表明,熔敷金属中铌的加入能明显提高其强度和塑性.但铌的质量分数达到3.5%后,虽然熔敷金属的强度进一步提高,但形成了脆性的金属间化合物Laves相,导致熔敷金属低温韧性下降.     

不锈钢表面激光熔敷层组织与耐磨性研究

不锈钢表面激光熔敷层组织是以焊条为基础材料,并采用激光基础材料新技术,并通过变化焊条的成分来实现不锈钢结构和耐磨性的。在此进行了对激光熔敷层组织的分析和研究,并发现以焊条为基础材料制备的不锈钢表面激光熔敷层组织具有很好的耐磨性;如果钛元素的含量越高,其耐磨性也越好;此外,钴元素的使用量增大,对其耐磨性有很大程度地改善作用。     

卷取机助卷辊表面堆焊研制

采用埋弧堆焊工艺在20CrNiMo表面堆焊6-8mm的Cr13系列新型马氏体不锈钢熔覆材料，分析熔覆金属的组织形貌，并进行耐磨性和硬度测定。研究结果表明，熔覆金属的焊态组织主要为板条状马氏体和大量的残余奥氏体，并伴有少量的回火马氏体，同时在马氏体间可见少量较小的碳化物。经500℃回火后其组织为回火马氏体和少量残余奥氏体，碳化物析出相增多。焊态硬度值为46-50HRC,回火后硬度值为54-58HRC,磨损失重是45#淬火钢的0.31倍。经过六个月的使用后，助卷辊的单边磨损量1.13mm,辊面平均硬度值在54.2HRC,说明该熔覆金属具有优异的耐磨性能。     

铌对9%Ni钢焊条熔敷金属组织和性能的影响

 研制9%Ni钢焊条的难点在于满足熔敷金属强度和塑性指标的前提下提高其低温韧性。本文在9%Ni钢焊条熔敷金属力学性能分析的基础上,采用彩色金相分析、扫描电镜分析、X射线衍射分析技术研究了Nb对9%Ni钢焊条熔敷金属组织和性能的影响。试验结果表明,熔敷金属中Nb的加入,形成了共格有序的金属间化合物γ'相(Ni3Nb)作为强化相,使熔敷金属得到有效的强化,但当Nb含量过高时,会形成是脆性的金属间化合物Laves相,导致熔敷金属低温韧性下降。Nb含量较低时,随着Nb含量的增加,熔敷金属强度和塑性显著提高,同时低温韧性下降很少。当Nb含量达到3.5(wt%)时,熔敷金属的强度和塑性继续提高,但低温韧性指标明显下降。     

Influence of Rare Earth Elements on Microstructure and Mechanical Properties of Cast High-Speed Steel Rolls

The influence of rare earth （RE） elements on the solidification process and eutectic transformation and mechanical properties of the high-V type cast, high-speed steel roll was studied. Test materials with different RE additions were prepared on a horizontal centrifugal casting machine. The solidification process, eutectic structure transformation, carbide morphology, and the elements present, were all investigated by means of differential scanning calorimetry （DSC） and scanning electron microscopy energy dispersive spectrometry （SEM-EDS）. The energy produced by crack initiation and crack extension was analyzed using a digital impact test machine. It was found that rare earth elements increased the tensile strength of the steel by inducing crystallization of earlier eutectic γ-Fe during the solidification process, which in turn increased the solidification temperature and thinned the dendritic grains. Rare earth elements with large atomic radius changed the lattice parameters of the MC carbide by forming rare earth carbides. This had the effect of dispersing longpole M C carbides to provide carbide grains, thereby, reducing the formation of the gross carbide and making more V available, to increase the secondary hardening process and improve the hardness level. The presence of rare earth elements in the steel raised the impact toughness by changing the mechanism of MC carbide formation, thereby increasing the crack initiation energy.     

金刚石复合片中稀土硬质合金基片的制备

采用共沉淀法制备含稀土的碳化物粉或含稀土的钴粉，通过真空烧结制成金刚石复合片用稀土硬质合金基片，并进行了性能的测定；研究了真空烧结过程中真空度对合金组织结构的影响。结果证明，稀土元素的加入使合金的平均抗弯强度提高了27％，而对硬度、密度无明显影响；可以通过控制硬质合金真空烧结过程中的真空度来调整合金的组织结构。     

Effect of Rare Earths on Microstructure and Properties of TiC-based Cermet／Cu Alloy Composite Wear Resistant Materials

The effect of rare earth (RE) oxide on the microstructure and properties of TiC-based cermet/Cu alloy composite hardfacing materials was investigated by using scanning electron microscope (SEM), transmission electron microscope(TEM), impact test and wear test. The mechanism of RE oxide for improving the phase structure and the impact toughness was also discussed. The experimental results indicate that the microstructure of the matrix can be refined, and the micro- porous defects can be eliminated by adding RE oxide into the composite materials. The polycrystalline and amorphous phase structure is formed at the interface of cermet and matrix metal. The formed structure enhances the conjoint strength of interface. The frictional wear resistance can be improved obviously, although the microhardncss of the matrix metal can not be effectively increased by adding RE oxide.     

Influence of Rare Earth on Property of Low Chromium Semi-Steel

Itisnoticeablethatthelowchromiumsemi steelhashighhardnessandabrasionresistance[1] .However,thematerialhaslowductility ,owingtothereticulatedistributionofcarbide ,whichrestrictsitsapplications .Therefore ,itisnecessarytoim provethecomprehensivepropertiesforpotentialap plications .Thecomprehensive propertiesoflowchromiumsemi steelcanbeimprovedbyaddingrareearths (RE)becauseREcanchangethemorphologyofcarbideandnon metallicinclusions ,refinegrainsize,purifyandstrengthen grainboundaryandsoon[2 -5] …     

添加微量稀土元素对Sn-Ag-Cu系无铅焊料性能的影响

以Sn-3．0Ag-0．5Cu（质量分数，％）焊料为母合金，探讨了微量稀土元素Ce、Er、Y和Sc对Sn—Ag—Cu合金物理性能、润湿性能以及力学性能的影响。试验结果表明：稀土元素对焊料的性能有不同的影响，添加微量Ce元素可以更好地改善焊料综合性能。     

Mechanism of Cracking Resistance of Hardfacing Specimens of Steel 5CrNiMo Improved by Rare Earth Oxide

The cracking morphology of the hardfacing specimens taken from steel 5CrNiMo was observed. Meanwhile, the residual stress fields were measured and simulated. Based on experiment mentioned above, the improved structure and modified inclusion in hardfacing metal with rare earth （RE） oxide were analyzed. The results show that, the hardfacing crack is initiated from the coarse dendritic crystal grain boundary, inclusions and coarse austenite grain boundary in the HAZ and propagated by the residual stress existing in the center of the hardfacing metal and HAZ. The primary columnar grain structure can be refined by adding RE oxide in the coating of the electrode. The inclusion in the hardfacing metal can be modified as well. Meanwhile, if the martensite transformation temperature is decreased, the largest value of the residual tensile stress in the dangerous region can be reduced.     

Effects of Rare Earth Elements on Properties and Structure of WC－14TiC－8Co Cemented Carbide

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Effect of Rare Earth Elements on Thermal Fatigue Property of Low Chromium Semi-Steel

The effect of rare earth elements on eutectic carbide‘s morphology of low chromium semi-steel in as-cast state and after heat treatment was investigated, and accordingly, the thermal fatigue property of this material was studied. The results show that RE can improve the eutectic carbide‘s morphology, inhibit the formation and propagation of thermal fatigue cracks, therefore, promote the thermal fatigue property, which is more noticeable in case of the RE modification in combination with heat treatment. The optimal thermal fatigue property can be obtained when treated with 0.2% RE modification as well as normalization at 950℃ for 3h.     

Effect of Rare Earth on Thermal Shock Resistance of Steel 9Cr2Mo

Ｒａｒｅｅａｒｔｈｅｌｅｍｅｎｔｓｈａｖｅｂｅｅｎａｄｄｅｄｉｎｔｏｈｏｔｒｏｌｌｅｒｓｔｅｅｌ.ＲＥｅｌｅｍｅｎｔｓｃａｎｉｍｐｒｏｖｅｔｈｅｒ ｍａｌｆａｔｉｇｕｅ[1] ,ｌｏｗｆｒｅｑｕｅｎｃｙｆａｔｉｇｕｅ[2 ] ,ｐｌａｓ ｔｉｃｉｔｙａｎｄｔｏｕｇｈｎｅｓｓ[3] ,ｒｅｆｉｎｅａｕｓｔｅｎｉｔｉｃｇｒａｉｎｓｉｚｅ[4] ａｎｄｍｏｄｉｆｙｉｎｃｌｕｓｉｏｎｓ[5 ] ｏｆｈｏｔｒｏｌｌｅｒｓｔｅｅｌ 6 0ＣｒＭｎＭｏ .Ｓｔｅｅｌ 9Ｃｒ2Ｍｏｉｓａｔｒａｄｉｔｉｏｎａｌｃｏｌｄｒｏｌｌｅｒｓｔｅｅｌ.Ｗｈｅｎ…     

Effect of Rare Earth Elements on Carbide Morphology and Phase Transformation Dynamics of High Ni-Cr Alloy Cast Iron

ＥｆｅｃｔｏｆＲａｒｅＥａｒｔｈＥｌｅｍｅｎｔｓｏｎＣａｒｂｉｄｅＭｏｒｐｈｏｌｏｇｙａｎｄＰｈａｓｅＴｒａｎｓｆｏｒｍａｔｉｏｎＤｙｎａｍｉｃｓｏｆＨｉｇｈＮｉＣｒＡｌｏｙＣａｓｔＩｒｏｎＹａｎｇＱｉｎｇｘｉａｎｇ（杨庆祥），ＬｉａｏＢｏ（廖波...