Study on process of roll bonding stainless and carbon steel under non-vacuum condition

The non-vacuum roll bonding method of nickel plating on the base materials is put forward in accordance with the primary problems existed in the roll bonding of stainless/carbon steel. After nickel plating test on the base materials, the microstructure of nickel cladding is observed by scanning electron microscopy （SEM） at high, and room temperature, and the results show that the nickel cladding on base material can be protected from oxidation in the high temperature. Non-vacuum roll bonding tests of nickel plating on base materials are done by the roll bonding equipment, and the roll bonding plates of stainless/carbon steel are obtained. The microstructure and the elements distribution of non-vacuum roll bonding interface are analyzed by optical microscope （OM） and SEM. The results reflect that the nickel plating layer and the base materials bond well.     

The Oxidation and Carburisation of a 20/25/Nb Steel in Carbon Dioxide,in Carbon Monoxide and in Carbon Dioxide-Carbon Monoxide Mixtures

Abstract

The oxidation and carburisation of a 20% Cr/25% Ni/Nb austenitic steel has been investigated between 600° and 850° in carbon dioxide, carbon monoxide and their mixtures at pressures within the range 0·04–760 cm.

Under all conditions the oxide formed markedly inhibits the attack of the steel. In carbon dioxide, the major reaction is M + CO₂ = MO + CO with the reaction 2M + CO₂ = 2MO + C contributing less than 7% to the total weight gain. All the carbon deposition appears to take place within the first few hours of the oxidation. Detailed studies show that the deposited carbon diffuses into the steel.

In carbon monoxide, the reaction is essentially M + CO = MO + C, the carbon passing through the oxide film into the steel. Carbon is also deposited in varying amounts on the surface of the oxide by the reaction 2CO = C + CO₂. This carbon is present as a filamentary growth and diffuses only slowly into the steel.

In carbon dioxide-carbon monoxide mixtures containing up to 75 vol.-% carbon monoxide, the steel reacts mainly with the carbon dioxide at 650° and 725°. At 800°, however, significant reaction occurs between the steel and the carbon monoxide.

The distribution of the carbon which enters the steel depends upon the temperature of oxidation. Below 750° the carbon concentration steadily decreases as the penetration into the steel increases. At 750° and above, the carbon concentration-penetration curves are anomalous: a maximum carbon concentration is obtained within the body of the steel.     

Effect of Metal Cations on Corrosion Behavior and Surface Structure of Carbon Steel in Chloride Ion Atmosphere

In order to better understand why the corrosion behavior of carbon steel exposed in Nansha atmospheric environment is very serious, the effect of sodium, potassium and magnesium chlorides deposited on carbon steel surface has been studied under atmosphere conditions by wet/dry accelerated test. The difference of corrosion behavior and surface structure in Na⁺, K⁺, and Mg²⁺ containing atmosphere has been investigated by thickness loss, scanning electron microscope, X-ray diffraction and electrochemical techniques. The results indicate that the thickness loss of carbon steel exposed in different metal cations containing atmospheric environment increases in the order of Na⁺, K⁺, Mg²⁺. The hard metal cation can promote the dissolution of the steel to a certain extent. In Mg²⁺ containing atmosphere, the relative content of β-FeOOH is rather higher and the protective ability index α*/γ* decreases in the order of Na⁺, K⁺, Mg²⁺. The corrosion current density of both bare carbon steel and the rusted carbon steel increases in the order of Na⁺, K⁺, Mg²⁺. The polarization resistance and the charge transfer resistance decreases in the order of Na⁺, K⁺, Mg²⁺.     

Influence of post-weld heat treatment on microstructure and properties in heat-affected zone of KMN steel joint

The influence of temperature during post-weld heat treatment on the microstructure and properties of KMN steel joints was investigated. The results reveal that after heat treatment, the martensite transformed to tempered sorbite, causing the softening of the resultant joints. XRD test shows that the residual austenite content decreased obviously when the joint was heattreated at 550 ℃ and 580 ℃, which degraded the impact toughness of heat-affected zone （ HAZ）. When the heat treatment temperature increased further, the dispersion strengthening from the precipitation of alloying elements improved the impact toughness of HAZ. The aggregation and coarsening of carbide also contributed to the improvement of impact toughness of HAZ.     

Pulsed TIG welding-brazing butt joints of aluminum-stainless steel thin plates with different fillers

Aluminum and stainless steel plates with 1.5 mm thickness are joined by pulsed TIG welding-brazing process with ER1100, ER4043 and ER2319 fillers, separately. Good weld formation can be obtained by adjusting appropriate pulse parameters. The effects of the fillers on that the thickness of the intermetallic compound （ IMC ） and tensile strength of the joints are investigated. SEM results indicate layer with ER2319 filler is about 2 ~m, which is thinner than 2. 5 p~m of ER1100 filler and 3.5 txm of ER4043 filler. Moreover, the element distribution in both IMCs and welded seams with three fillers are different because of the different compositions of fillers. The results of mechanical property tests suggest that the joint strength with ER2319 filler is the highest, while the joint impact energy is the lowest. The joint with ERllOO filler exhibits the best comprehensive mechanical pet.formanee.     

TIG welding-brazing joint of aluminum to stainless steel with hot wire

TIG welding-brazing process with high frequency induction hot wire technology was presented to create joints between 5A06 aluminum alloy and SUS32! stainless steel using ER1100 filler wire with different temperature. The joints were evaluated by mechanical test and microstructural analyses. The welding procedure using hot fiUer wire （400 ℃ ） significantly increases strength stability by 71% and average value of tensile strength by 30. 8 % of the joints, compared with cold wire. The research of microstructures in interfaces and welded seams reveals that using 400 ℃ hot filler wire can decrease the thickness of intermetallic compounds （ IMCs ） from 6 to 3.5 txm approximately, which is the main reason of mechanical property improvement.     

Microstructure and properties of SAF2507 superduplex stainless steel welded joints

SAF2507 plates （ 12 mm thickness ） were welded using shield metal arc welding （SMAW） process with E2594 electrode. The microstructure, o-phase, and impact fraetograph of the welded joints were analyzed using optical microscope and scanning electron mieroseope. The results show that the fusion zone consists of ferrite, chromium nitride, and secondary aastenite precipitation when welding is performed at low heat input （0. 5 kJ/mm）. However, the increase in heat input causes precipitation of brittle o＂ phase at the y/c~ interface in weld metal and heat-affected zone, as well as a brittle fracture along the grain boundary. Heat input in the range of O. 5 kJ/mm to 1.5 kJ/mm is suitable for joining SAF2507 plates.     

Welding deformation control of medium-thickness structures made by advanced high strength steel

In order to investigate the residual angular deformation in fillet welding of T-joint of HG785 high strength steel with a medium thickness plate, both detailed thermo-mechanical finite element simulation and conventional gas metal arc welding experiment were carried out in the present study. In-process deformation control method using backheating method to reduce the residual deformation was discussed.     

FEM simulation on residual stress distribution during diffusion bonding between Ti （ C,N） metallic ceramic/interlayer/40Cr steel

Based on ANSYS FEM software, the distribution of residual stress in the diffusion bonding joints between Ti（ C,N） metallic ceramic/interlayer/4OCr steel was calculated and experimentally ver~ed. The results showed that the trend on the distribution of residual stress field in the joints was not changed with the use of interlayer. The maximum residual stress was always located in metallic ceramic with area ranging from 1 mm to 4 mm to the interlayer. The maximum residual stress in the joints was also affected by diffusion temperature. The satellite pulse current during the initial stage on diffusion bonding can promote the formation of liquid film at the interface, by which diffusion temperature and loading pressure can be greatly decreased. The crack initiation was easily produced at the corner of Ti （ C, N） metallic ceramic close to the interlayer. If a higher residual stress produced in the joints, the crack was propagated into the whole ceramic.     

Ni-P-PTFE镀层表面黏液形成菌的污垢特性

目的 研究Ni-P-PTFE镀层改性换热面对微生物污垢的抑制作用.方法 调整化学镀工艺,在换热器常用的低碳钢表面制备不同性能的复合镀层,获取镀层厚度、镀速和表面能等参数.对低碳钢和Ni-P-PTFE复合镀层进行微观形貌对比,并进行黏液形成菌污垢静置实验,测量菌悬液中的细菌数量变化及试样质量变化.分析复合镀层表面在黏液形成菌污垢实验前后的宏观和微观形貌,与低碳钢试样进行对比,研究复合镀层试样表面能和镀层表面污垢沉积的关联性.结果 Ni-P-PTFE复合镀层改变了换热面的表面性能,接触角明显增大,表面能由改性前的49.16 mJ/m2降低到7.54 mJ/m2.与低碳钢的静置结果 相比,悬挂复合镀层试样的菌悬液中黏液形成菌数量显著减少,复合镀层试样表面平均污垢沉积量减少到2.3 g/m2(低碳钢表面为12.1 g/m2).结论 Ni-P-PTFE镀层可以有效抑制黏液形成菌的生长,低表面能有效减少了微生物污垢的沉积,使其表现出良好的耐蚀性和抗垢性.     

Synthesis and characterization of carbon nanotubes reinforced Al-Si-Cu brazing powder

In this paper, an approach to synthesizing carbon nanotubes （ CNTs ） reinforced A1-Si-Cu brazing powder was studied, which was accomplished by in-situ growth of the CNTs on the Al-Si-Cu powder at a relatively low temperature by plasma enhanced chemical vapor deposition （ PECVD ）. The synthesis parameters were optimized. The component of brazing powder was analyzed by X-ray diffraction （ XRD ）. The microstracture and dispersity of as-grown CNTs were investigated by scanning electron microscopy （SEM）. The graphitization and defects were characterized by Raman spectroscopy. The asgrown CNTs on Al-Si-Cu powder disperse uniformly and have moderate length and density, meanwhile its sp2 structure dominates minor quantity of amorphous carbons and defected carbon structures.     

重碳酸盐溶液中SO_4~(2-)和Cl~-对低碳钢活化/钝化腐蚀行为的影响

在除O_2的0.1 mol/L NaHCO_3,0.1 mol/L NaHCO_3+0.1 mol/L Na_2SO_4以及0.1 mol/L NaHCO_3+0.1 mol/L NaCl溶液中,用恒电位法在低碳钢电极表面制备腐蚀产物,并原位监测低碳钢的开路电位,用SEM观察腐蚀形貌,用XRD确定腐蚀产物的相组成.结果表明.在0.1 mol/L NaHCO_3溶液中,低碳钢的开路电位最终处于再钝化区间,其表面未观察到明显的腐蚀现象;在0.1 mol/L NaHCO_3+0.1 mol/L Na_2SO4溶液中,低碳钢的开路电位最终处于再活化区间,其表面发生均匀腐蚀;在0.1 mol/L NaHCO_3+0.1 mol/L NaCl溶液中,低碳钢的开路电位最终亦处于再活化区间,而其表面却发生局部腐蚀,XRD结果表明,低碳钢表面的腐蚀产物主要为Fe_3O_4和α-FeOOH.     

低碳钢基体上电沉积聚苯胺膜及耐蚀性研究

在草酸溶液中．采用恒电流阳极电解法在低碳钢上制备了聚苯胺膜层，该电解过程主要包含金属活性溶解-钝化-聚苯胺膜聚合沉积等三个先后发生的步骤。所得聚苯胺膜呈蓝绿色，均匀致密，与低碳钢基体的结合较好。在氯化钠溶液中的电化学测试表明，聚苯胺膜的存在可以显著地提高低碳钢的耐腐蚀性和抗点蚀能力。     

氯离子和电偶腐蚀对碳钢在热钾碱溶液中腐蚀的影响

研究了Cl-对碳钢和不锈钢在(K2CO3+KHCO3+ V2O5)溶液中腐蚀的影响,结果表明Cl-对阳极钝化曲线所示的腐蚀电位、钝化区间、过钝化电位和析氧过程无明显影响,未见试样有孔蚀的迹象.但随着Cl-离子浓度增大,其维钝电流密度也增大.90℃时,不锈钢-碳钢在此溶液中构成电偶腐蚀时,测得碳钢腐蚀速率为0.064 mm/a,比未成偶对时碳钢的腐蚀速率大一倍.90℃时,将已钝化的不锈钢-碳钢在(K2CO3+KHCO3)溶液中构成电偶腐蚀时,测得碳钢腐蚀速率为4.0 mm/a,比含有V2O5溶液中碳钢的腐蚀速率大64倍.     

氧化铈对低合金钢焊条力学性能的影响

在低合金钢焊条药皮过渡微量的稀土氧化铈,通过用MATLAB函数辅助计算、曲线拟合,得出氧化铈与熔敷金属力学性能的定量关系公式.结果表明,定量关系公式误差较小,抗拉强度误差由原来的44MPa降为1MPa,下屈服强度误差由原来的100MPa降为2MPa.把稀土元素换算成碳当量,引入低合金钢焊条配方设计公式中,减少了试验次数,降低了焊条设计成本.     

Evaluation of four commercially produced surface treatments

The paper reports the results of characterization of four commercial surface treatments on M2 tool steel substrates. The treatments characterized were (a) TiN deposited by physical vapor deposition (PVD), (b) TiCN/TiN multilayer also deposited by PVD, (c) diamond-like carbon (DLC) deposited by an ion-assisted technique, and (d) vanadium carbide (VC) produced by a thermal diffusion process. The surface treatments were evaluated for characteristics relevant to their tribological performance, such as thickness, roughness, chemical composition, micro- and nanohardness, coating-substrate adhesion, and wear resistance. In addition, a hardness model developed at the University of Newcastle upon Tyne (United Kingdom) to correct for substrate effects was successfully applied. Nanohardness tests also yielded the elastic modulus values of the surface treatments, while scratch testing used for determining coating-substrate adhesion provided qualitative information on their ductility.     

马氏体不锈钢堆焊层组织和耐冲蚀性能

采用2Cr13和经过V、Ti、Nb、N微合金化改性处理的1Cr13马氏体不锈钢进行埋弧堆焊试验,分析微合金元素和热处理工艺对马氏体不锈钢堆焊层显微组织和耐冲蚀性能的影响。研究结果表明:微合金元素V、Ti、Nb与C、N在奥氏体形核初期形成大量颗粒细小、弥散分布的稳定化合物,使堆焊层金属的晶粒得到细化;奥氏体晶粒稳定后,这些化合物又起到析出强化的作用;回火后,部分碳化合物在马氏体板条间析出,起到了二次强化的作用,同时降低马氏体中的碳含量,改善基体韧性。较好的基体强韧性配合最终提高了材料的耐冲蚀性。     

反应堆压力容器用低合金钢焊丝焊态熔敷金属疲劳性能研究

采用一种免焊后热处理的回火焊道焊接工艺在碳钢试板上进行反应堆压力容器用低合金钢焊丝堆焊工艺试验,获取低合金钢焊丝焊态熔敷金属。根据ASTM E466和ASTM E606标准对焊态熔敷金属进行室温下低周和高周疲劳性能试验,并使用Coffin-Mansion方程与三参数方程拟合焊态熔敷金属低周疲劳和高周疲劳寿命曲线。同时,根据核电设备设计规范RCC-M中推荐的修正系数对试验获得的疲劳曲线进行修正,获得修正后的S-N曲线,并与RCC-M规范中低合金钢疲劳设计曲线进行对比。试验结果表明:基于RCC-M修正后的焊态熔敷金属低周疲劳S-N曲线与RCC-M中的低合金钢低周疲劳设计曲线基本重合;基于RCC-M修正后的焊态熔敷金属高周疲劳S-N曲线位于RCC-M中的低合金钢高周疲劳设计曲线之上。     

Na2MoO4-有机膦A复合缓蚀剂对55%LiBr溶液中碳钢的缓蚀行为

采用失重法、电化学测试技术、原子力显微镜和电子探针显微分析等方法考察了Na₂MoO₄-有机膦A复合缓蚀剂对55%LiBr+0.07 mol/L LiOH溶液中碳钢的缓蚀性能。结果表明,240 ℃下碳钢在添加800 mg/L Na₂MoO₄-有机膦A复合缓蚀剂的55%LiBr+0.07 mol/L LiOH溶液中的腐蚀速率为43.2 μma^-1。在沸腾的55%LiBr+0.07 mol/L LiOH溶液中添加该缓蚀剂后,碳钢的钝化电位区间拓宽,钝化电流密度降低,反应电阻R_t值显著增加,缓蚀效率可达94.4%。该缓蚀剂能使碳钢表面形成显微结构为孤岛状的膜层,主要成分为Fe和Mo的氧化物。     

两种涂层和两种钢在液/固两相流中冲刷与腐蚀的交互作用

用失重法和电化学法系统地研究了20钢基体、两种Ni基涂层(Ni60JH和Delelo50)以及对比材料lCrl8Ni9Ti不锈钢在液／固两相流(5％H2SO4 15％石英砂)中冲刷与腐蚀的交互作用．实验表明：(1)在冲刷速率为5—10m／s时，Ni60JH涂层的耐冲刷腐蚀性能比基体高8—15倍多，并优于1Crl8Ni9Ti不锈钢；DelelO50涂层的耐冲刷腐蚀性能比基体高3—5倍多．(2)随着冲刷速率的提高，4种材料的冲刷腐蚀交互作用失重率在冲刷腐蚀总失重率中所占比例显著增大，由低速时的45％增加到高速时的80％，从而使冲刷腐蚀交互作用失重率在冲刷腐蚀总失重率中占主导地位．(3)在纯腐蚀中，Ni60JH涂层和1Crl8Ni9Ti不锈钢以均匀腐蚀为主要特征，而DelelO50涂层和20钢以选择性腐蚀为主要特征．