Effects of Oxygen,Nitrogen, and Carbon on The Ductility of Cast Molybdenum

High purity molybdenum ingots containing controlled amounts of a single impurity element (oxygen, nitrogen, or carbon) were prepared. These ingots were tested for ductility by bending test specimens at various temperatures. The relationship between the plastic behavior of the ingots and their chemical composition has been determined.     

有害杂质（Al,Ti）对铁基非晶磁性的影响及其改善方法

介绍了非晶合金中的微量元素Ａｌ和Ｔｉ对铁基非晶薄带磁性的影响及薄带表面结晶形态与磁性的关系，分析了有害杂质Ａｌ、Ｔｉ作用机理。指出可添加微量Ｓｎ和Ｓ来抑制Ａｌ和Ｔｉ的有害作用，能使合金磁性能得到恢复，达到可用低纯度原料来生产优质磁性非晶带材的目的。     

An X-ray photo-electron spectroscopic study on the role of molybdenum in increasing the corrosion resistance of ferritic stainless steels in HC1

X-ray photo-electron spectroscopy has been used to investigate the correlation between composition of surface films and the beneficial effects of molybdenum addition to high purity, 30Cr ferritic stainless steels in improving the corrosion resistance properties in HCI. It has been found that the passive films formed consist mainly of hydrated chromium oxy-hydroxide and the composition of the films on 30Cr and 30Cr-2Mo stainless steels is essentially the same, except for the existence of a small amount of hexavalent molybdenum on the latter steel. The surface film formed in the active region contains a large amount of hexavalent molybdenum. The beneficial effects of molybdenum have been interpreted as follows: molybdenum eliminates the active surface sites through the formation of molybdenum oxy-hydroxide or molybdate on these site, on which it is difficult to form the stable passive film. This leads to the appearance of a homogeneous steel surface and to the formation of a homogeneous passive film.     

2.25Cr-1Mo-0.25V钢焊缝冲击性能和显微组织分析

进行了2.25Cr-1Mo-0.25V钢的焊条电弧焊试验,测定其焊缝的成分和冲击吸收功,进行了金相及启裂源观察,对冲击吸收功较低的样品进行脱脆处理.结果表明,冲击吸收功较低的焊缝的Mn,Si,Mo及其杂质元素含量相对较高,Mn,Si,Mo等元素促进杂质元素在晶界上的偏聚,致使晶界性能变坏,断口以沿晶断裂为主,冲击吸收功降低,脱脆处理后,冲击韧性恢复说明焊缝存在高温回火脆性,导致高温回火脆性是由于杂质元素在晶界上的偏聚,因此研制焊条时要严格控制Mn,Si,Mo和杂质元素的含量.     

Influence of chromium,molybdenum and cobalt on the corrosion behaviour of high carbon steels in dependence of heat treatment

High chromium martensitic steels are designed to provide high corrosion resistance in combination with high strength. Some of these steel grades contain primary carbides for improving the wear resistance, e.g. the steel 440C. The present paper mainly deals with the effect of chemical composition and microstructure on the corrosion properties. Different experimental alloys were produced in the shape of small ingots. The influence of the alloying elements chromium, molybdenum, cobalt, and carbon on the corrosion properties was studied. The results can be summarized as follows: Chromium and molybdenum improve the corrosion resistance, however, only the content of these elements in solid solution in the steel matrix is effective. In case of cobalt the corrosion resistance decreases. The reason is the interaction between cobalt and carbon and its effect on the chromium content in the steel matrix. The calculated pitting resistant equivalent number of high chromium martensitic steels is only limited valid, because there is a major effect of carbide precipitation on the corrosion behaviour. Further investigations were focused on the heat treatment. Especially the effect of the tempering temperature of these steels was studied. The tempering temperature is most relevant for secondary hardening carbide precipitation, which lowers the chromium content of the matrix with detrimental influence on the corrosion properties. The carbide precipitation and chromium distribution was characterized by means of energy filtered transmission electron microscopy (EFTEM).     

Purification of niobium by multiple electron beam melting for superconducting RF cavities

In this work, purification of commercial grade (∼99.9 %) niobium by multiple Electron Beam Melting (EBM) is reported. Impurity removal of carbon, oxygen, nitrogen, aluminum, iron, molybdenum, zirconium and tungsten in niobium matrix is presented as a part of the ingot melting stages. The minor material loss of niobium during melting is attributed to the amount of decarburization based on the ratio of initial and critical content of oxygen to carbon. The analysis of nearly 60 impurity elements in niobium was carried out by glow discharge mass spectrometry. In the end, the purity of niobium after multiple electron beam meltings was found to be 4N while the purity enhanced from 99.9 % (3N) to 99.993 % (4N3), including gaseous impurities, and 99.98 % (3N8) to 99.998 % (4N8) without gaseous impurities. The glow discharge mass spectrometry analytical results of purified niobium indicated that the material is suitable as input material for further processing of fabricated superconducting radio-frequency cavities.     

Effects of the lanthanum content on the microstructure and properties of the molybdenum alloy

The effects of the lanthanum content on the microstructure and properties of molybdenum alloy were investigated. The molybdenum powders with various lanthanum contents were prepared by a solid-liquid doping method and reduction under hydrogen atmosphere, which could be processed into sintered molybdenum and rotary swaged molybdenum. The results indicated that the grain sizes of the alloys became finer and the tensile strength increased with increasing La content. The La₂O₃ particles could adsorb impurity elements that existed on the grain boundary and generate the amorphous structure around the particle. The rotary swaged Mo with 0.1 wt.% La was the highest tensile strength, and the rotary swaged Mo with 0.03 wt.% La possessed the highest elongation to failure of 42%. In addition, the electrical resistivity of the rotary swaged Mo increased at first and later decreased with increasing La content.     

Influence of nickel and molybdenum on the phase stability and mechanical properties of maraging steels

The effect of nickel and molybdenum concentrations on the phase transformation and mechanical properties of conventional 18Ni(350) maraging steel has been investigated. Both of these elements act as strong austenite stabilizers. When the concentration of molybdenum or nickel is greater than 7.5 or 24 wt %, respectively, the austenite phase remains stable up to room temperature. In both molybdenum- and nickel-alloyed steels, the austenite phase could be transformed to martensite by either dipping the material in liquid nitrogen or subjecting it to cold working. When 7.5 wt% Mo and 24 wt% Ni were added in combination, however, the austenite phase obtained at room temperature did not transform to martensite when liquid-nitrogen quenched or even when cold rolled to greater than 95% reduction. The aging response of these materials has also been investigated using optical, scanning electron, and scanning transmission electron microscopy.     

合金元素对T/P91钢焊缝组织及性能的影响

通过T/P91钢焊条的研制,研究了不同合金元素种类及含量对焊缝组织及性能的影响,结果表明,在其它合金元素含量相近的情况下,钼元素能够明显降低焊缝的相变点,熔敷金属中的钼含量应当按照标准要求的上限选取.     

标准加入法测定纯钯中的杂质元素

高纯金属纯度分析时为了克服基体效应的影响,常采用分离基体、基体匹配等方法对其中杂质元素进行分析测定,但是存在基体难分离、易造成样品污染,而且还会消耗昂贵基体等问题。以王水溶解纯钯样品,通过选择合适的谱线克服光谱干扰,采用标准加入法绘制校准曲线,在不分离基体或者不使用基体匹配的前提下消除了钯基体对杂质元素测定的基体效应影响,实现了ICP-AES对纯金属钯中30多种杂质元素的直接定量测定。将实验方法应用于纯钯样品的实际样品分析,加标回收率为92.1%~106.8%,相对标准偏差(RSD,n=7)不大于10%。     

超细晶粒钢HAZ晶粒长大的规律

研究了低碳钢、普通市售Ｘ６５钢和高洁净度Ｘ６５钢三种超细晶粒钢焊接ＨＡＺ的晶粒长大倾向。试验结果表明,这些超细晶粒钢都具有严重的晶粒长大倾向;低碳超细晶粒钢比Ｘ６５超细晶粒钢有更为严重的晶粒长大,这是因为前者不含有能阻碍晶粒长大的稳定碳、氮化物形成元素Ｎｂ和Ｔｉ,而后者中含有这些元素;高洁净度Ｘ６５超细晶粒钢的ＨＡＺ晶粒长大倾向小于普通市售Ｘ６５超细晶粒钢。这是因为钢中杂质元素含量越多,α→γ转变温度越低,即Ａｃ３点越低,在同样的焊接热循环条件下,普通市售Ｘ６５超细晶粒钢中的γ晶粒在高温停留时间就越长,晶粒长大的程度也就越大。     

稀土在硅锰铸钢件上的应用

对硅锰铸钢添加稀土后的铸态组织、断口、热处理组织进行了观察分析，认为硅锰铸钢中添加稀土后，对铸态组织、夹杂物、淬火组织产生良好的影响，从而使铸钢的冲击韧度有较大幅度的提高。在保证硅锰铸钢淬火、低温回火后，吼值大于200KJ／m^2的前提下，可提高硅锰铸钢的含碳量，使其耐磨性提高，为扩大硅锰铸钢的应用范围创造了有利条件。     

The influence of copper, molybdenum and silicon on the corrosion electrochemical behavior of austenite chromium-nickel steel

The role of copper, molybdenum and silicon in the anodic behavior of a X16H14 type steel in a sulfuric acid solution is investigated with the use of tracer technique. It is shown that molybdenum and copper enhance its corrosion resistance by slowing down active dissolution and faclitating the steel passivation. With regard to these characteristics, copper, especially if combined with silicon, is superior to molybdenum. Silicon does not affect these properties in the absence of copper and molybdenum but enhances the susceptibility of a copper-containing steel to intergranular corrosion. The iron-chromium-nickel base of steels, in turn interacting with the solution, activates the dissolution of the alloying copper and molybdenum. The results are interpreted in terms of active centers causing the surface reactivity.     

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通过金相、扫描及系列冲击等试验方法研究了洁净度对38CrMoAl钢韧脆转变的影响。结果表明,低洁净度电炉钢与高洁净度双真空钢的韧脆转变温度都是-60℃。但是,在整个连续冲击试验温度范围内,DV钢的冲击韧性均高于EF钢。在连续冲击的上平台区,前者比后者高25 J左右,随着温度下降两者的差距随之降低,在上下平台之间区域内,前者比后者高5~10 J,随着温度继续下降进入到下平台区域,两者差距越来越小,直至差距为零。低的S、P元素含量,较少的MnS、AlN夹杂物是洁净度较高的DV钢韧性较好的主要原因。     

Metal dusting in CCR platforming unit

The mechanism of metal dusting of 9Cr-1Mo steel in CCR platforming unit, based on examinations of a charge heater tube, is presented. The tube operated for 10 years, and the metal skin temperature was about 600 °C. The feed was composed of hydrotreated naphtha and hydrogen gas. The mechanism of the corrosion was elucidated using scanning electron microscopy, electron probe microanalysis and X-ray diffraction technique. It has been found that the carbon deposition on the steel surface and its inward diffusion into the steel is accompanied by the outward diffusion of carbide forming elements, i.e. chromium and molybdenum. At an advanced stage of the metal dusting process a thin layer of fine chromium-rich carbides beneath the steel surface exists. The layer is followed by a porous zone composed of big degraded primary carbides and fine carbides instead of alloy ferrite, with chromium and molybdenum content higher than the ferrite inside the tube wall. On the steel surface, a layer of coke composed of graphite, iron and M₇C₃ carbides is formed and the uniform wastage of the steel takes place. Possible influence of some sulphur additions to the CCR platformer feed during the future service on degradation of the subsurface material has been considered.     

Remarkable effect of Ce base element purity upon glass forming ability in Ce–Ga–Cu bulk metallic glasses

Raw Ce element materials of eleven different purities are used to prepare bulk metallic glasses with the same nominal composition of Ce₇₀Ga₈Cu₂₂ (at.%). In the high-purity regime of Ce (98.13–99.87wt.%), three distinct peaks are observed in the curve plotting the purity vs. the glassy rod critical diameter (D_c); and with ∼0.11 wt.% decrease in purity, the D_c can increase sharply from 1 to 10 mm. In the relatively low-purity regime of 96.15–98.13 wt.%, the low material purity is found to be beneficial for glass formation; and with a ∼0.61 wt.% decrease in purity, the D_c increases dramatically from 1.5 mm to at least 20 mm. Such a sensitive and systematic purity-dependent glass-forming ability has rarely been reported before in metallic glasses. It is also suggested that the high stability of the competing crystalline phases results from the mixture effect via addition of multiple impurity elements into the matrix glass-forming alloys, and that this addition of impurity elements may be the dominant factor responsible for their intrinsic glass-forming ability of these alloys. The results provide systematic evidence for the strong purity and composition effects that are present in glass formation, and can be used to shed light on scientific research and industrial applications in the field of metallic glasses.     

On the Possibility of Replacing Vanadium and Molybdenum in Alloy VT16 with Iron

The mechanical properties of alloys of the Ti – Al – V – Mo system equivalent in phase composition to alloy VT16 are studied with the aim of determining the possibility of replacing the expensive alloying elements with iron. It is shown that the ductility of an alloy of type VT16 in which molybdenum has been replaced with iron is somewhat higher than in the case of replacement of vanadium with iron. The conclusion is that vanadium and molybdenum in alloy VT16 can be partially replaced with iron without a deterioration in the mechanical properties.     

铁液纯净度对铸铁件质量的影响

综述了微量元素Pb、Te、As、Ti对灰铸铁件组织和性能的影响规律以及对球铁件质量的影响情况;介绍了Ti、V、Pb、Te等元素含量与铸件加工性能的关系;认为可通过使用高纯生铁、优质铸造材料,优质废钢+增碳工艺的感应炉熔炼、冲天炉+感应电炉双联熔炼,利用RE消除微量元素的不利影响等措施来提高铁液的纯净度。     

改变铬和钼的含量对38CrMoAl钢性能的影响

研究了常规38CrMoAl钢和提高铬含量、降低钼含量的38CrMoAl钢在调质态力学性能和渗氮层深度、耐磨性和组织结构方面的差异,探索通过改变成分来降低38CrMoAl钢成本的可行性。结果发现,钼含量降低,铬含量提高,使材料的强度提高,韧性和塑性稍稍降低,而渗氮层变厚,表面硬度和耐磨性提高。     

熔炼方法对银熔体材料纯度、组织和电性能的影响

分析了熔炼方法对银熔体材料纯度、微观组织和电阻率的影响。对比普通熔炼方法,二次熔炼方法得到的银材料由II号银(99.95%)变成I号银(99.99%);氧含量降低至少85%以上,纯银熔体材料电阻率降低约1.54%。杂质元素主要集中在晶界处,纯银熔体材料电阻率随杂质含量的减少而减小,二次熔炼方法可有效提高纯银熔体材料质量、稳定其电学性能。