A flux-core wire for hardfacing sealing surfaces of stop valves

A new flux-cored wire producing the deposited metal of high-chromium steel of the Fe–Cr–Ni–Mo–Mn–Si–Nb–Ti–B alloying system is described. The structure of the deposited metal and the composition of the hardening phases are determined. The role of borides in increasing the wear resistance and stability of the properties of the metal in hardfacing is analysed.     

Multi-arc surfacing with coated electrodes

The results of investigations of the structure and properties of the deposited metal of the maraging steel of the Fe–Ni–Mo–Cr–V–Si–Ti–Al alloying system, hardened with boron compounds, are presented. The role of borides in the formation of the phase composition and the structural state of the steel in tempering is analysed. It is shown that this metal has high thermal and wear resistance. Consequently, it is recommended for hardfacing working surfaces of stamping tools.     

Effect of borides on the processes in metal deposited with 0Ni13Mo5Cr4VSiTiAl flux-cored wire at elevated temperatures

The results of investigation of the service properties of maraging Fe–Ni–Mo–Cr–V–Si–Ti–Al with a composite structure, containing boride compounds, are described. The results show that the presence of the borides in the composition of the 0Ni13Mo5Cr4VSiTiAl flux-cored wire improves the shielding properties of the oxide film on the surface of the metal at high temperatures and results in high heat and scale resistance.     

Hardening rolling rolls by hardfacing with an alloyed strip electrode under a ceramic flux

The composition of 20KhN4MFB coldrolled strip for hardfacing rolling rolls was determined and production started. The deposited layer is characterized by high impact toughness, plasticity and resistance to cyclic heat changes. Additional alloying to increase the hardness and wear resistance of the metal is carried out through a ceramic flux. The composition of the new ceramic flux is characterized by improved welding and technological properties and relatively low chemical activity. Hardfacing of the hot rolling rolls increases the volume of rolled material per 1 mm of the reduction of the roll diameter.     

抗冲击磨损奥氏体堆焊材料

针对具有冲击磨粒磨损工况条件，成功研制出了一种奥氏体堆焊材料EKCM50。该堆焊材料为Fe-Mn-Cr-Mo-V合金系，通过耐磨性对比试验分析，堆焊合金耐磨性能优于D256焊接材料。经过加工硬化冲击试验，EKCM50焊接材料堆焊层硬度由32HRC升高到45HRC，经过冲击磨损试验，40min后，试验材料堆焊磨损失重几乎不变。通过对该材料的加工硬化和磨损性能的试验研究，探讨了此种奥氏体材料的加工硬化及耐磨机理，以及加入的合金元素对该焊接材料的耐磨性及耐磨机理的影响规律。     

Fatigue life of multilayer hard-faced specimens

Specimens and the method for experimental evaluation of the fatigue life of multilayer hard-faced metal subjected to cyclic mechanical loading are described. The tests were carried out by three-point bending with cyclic non-zero loading in the centre of the specimen, which reproduces, with certain assumptions, the force loading characteristics of rolling rolls, the rolls of continuous casting installations and other tools and equipment for deformation of metals and alloys which are subjected in service to the simultaneous effect of cyclic mechanical and thermal loads. The proposed method is then used to investigate the durability of the specimens of 40Kh steel, hard faced with PP-Np-25Kh5FMS flux-cored wire with and without a ductile sublayer. The sublayer was deposited using Sv-08A solid wire or the PP-Np-25Kh5MF flux-cored wire. The experimental results show that the deposition of the ductile sublayer with Sv-08A and PP-Np-25Kh5MF wires increases the fatigue life of the deposited specimens 1.3 and 1.6 times, respectively. PP-Np-123Kh1MF wire, which produces a deposited metal with higher mechanical properties in comparison with the Sv-08A wire, results in a higher fatigue life of multilayer hard-faced specimens.     

First principles study of site substitution of ternary elements in NiAl

Site substitution of ternary elements in ordered compounds influences the electronic structure and hence the properties of compounds at the continuous level. The electronic structure and binding energy of a number of NiAl-X alloy systems (X=Ti, V, Cr, Mn, Fe, Co, Zr, Nb, Mo, Hf, Ta, W, Si, Ga, or Ge) were calculated using the discrete variational cluster method based on the local density approximation of the density functional theory. The site preference of the ternary additions to NiAl was investigated by employing the Bragg–Williams model to analyse the calculated binding energy. The results show that all the considered ternary elements possess stronger preference to the Al sublattice sites than a Ni atom does. A new method of identifying sublattice substitution of ternary additions in NiAl was proposed by comparison of the binding energies per atom of the ternary and the binary clusters involving the fourth nearest neighbours. The analysis suggests that Fe and Co atoms occupy the Ni sublattice sites, whereas Si, Ga and Ti atoms occupy the Al sublattice sites. The remaining elements may substitute for both sublattices: Mn is most likely to go for the Ni sublattice; V, Cr, Zr, Nb, Mo, Hf, Ta, W and Ge have a larger preference for the Al sublattice, but Cr and W do not show significant preference to any sublattice. The densities of states involving alloying additions of Co, Si and Cr were further investigated to clarify the site preference of the alloying additions.     

Microstructure and properties of Fe–Cr–C hardfacing alloys reinforced with TiC–TiB2

Abstract

Different amounts of TiB₂ powder were added to flux cores of wear resistant hardfacing flux cored wires for the preparation of new flux cored wires. Fe–Cr–C hardfacing alloys reinforced with TiB₂ were produced by arc hardfacing. The microstructure, hardness and wear resistance behaviour of the hardfacing alloys were investigated using an optical micrograph, scanning electron micrograph (SEM), X-ray diffractometer, macrohardness tester, microhardness tester and abrasive wear tester. The results showed that, among the hardfacing alloys, a new hard phase, i.e. TiC–TiB₂ composite compound particles, was formed and dispersed in the primary carbides and matrix structures. The TiC–TiB₂ reinforced Fe–Cr–C hardfacing alloys imparted greater hardness and better wear resistance. The presence of TiC–TiB₂ hard phase particles is the main reason for the improvement in hardness and wear resistance of Fe–Cr–C hardfacing alloys.     

HM1堆焊焊条的研制

针对3Cr3Mo3W2V焊条的药皮组成、堆焊工艺、堆焊层组织进行了较为系统的试验研究。试验结果表明：该焊条堆焊后，经热处理基本达到3Cr3Mo3W2V热作模具的工作要求。     

Influence of aluminium on the microstructure of Co based alloy coatings

Abstract

Coating contamination as a consequence of the diffusion of elements from the operating environment, accounts for the deterioration of a variety of mechanical components, and is particularly severe on those that operate at elevated temperatures. This study analysed the degradation of three Co based alloy coatings as a consequence of their contamination with Al. One Co–Cr–W and two Co–Cr–Mo–Si atomised alloy coatings, each with and without 5 wt-% aluminium powder, were deposited by plasma transferred arc on AISI 316L stainless steel plates. Accelerated aging at 600 and 1000°C contributed to the understanding of the effect of Al on the microstructure of coatings. Coatings with and without Al were characterised by laser confocal microscopy and microhardness. Dilution increased on coatings modified with Al due to the exothermic synthesis of aluminide compounds and the most significant microstructure modification was observed in the Co–Cr–Mo–Si coatings as primary Laves phase was almost suppressed. Accelerated aging tests showed that aluminium had a deleterious effect on the three Co based coatings although it was more pronounced in those processed with the Co–Cr–W alloy.     

均热温度对不同成分980 MPa级高强钢组织和性能的影响

采用Gleeble-3500热模拟试验机对两种不同成分的1.4 mm厚冷硬带钢进行退火热模拟试验,并利用万能拉伸试验机、光学显微镜、扫描电镜、EDS对所得热模拟退火试样进行力学性能和组织分析。结果表明,其他退火参数相同,低C高Mn成分前提下,添加合金元素Cr、Mo及高Si含量的C-Mn-Si(高)+Cr+Mo钢和不添加合金元素Cr、Mo且低Si含量的C-Mn-Si(低)钢经760、780 ℃均热退火可得到力学性能满足要求的980 MPa级双相钢。不同均热温度下,C-Mn-Si(高)+Cr+Mo钢组织均为铁素体、岛状马氏体和少量贝氏体,区别在于均热温度高的铁素体晶粒细小且数量较多,呈凹凸不平形貌,马氏体含量少一些,贝氏体呈针状或团簇状;C-Mn-Si(低)钢组织则由铁素体、马氏体、少量的贝氏体和残留奥氏体组成,区别在于均热温度高,铁素体晶粒细化,轧制特征不明显,马氏体含量少,贝氏体呈粒状且量较少。残留奥氏体呈亮白色条状,这种亮白色的特征主要是因为Mn的局部富集。两种试验钢组织差异本质上是Cr、Mo和Si 3种合金元素的含量差异影响过冷奥氏体稳定性引起的。     

Microstructural design of hardfacing Ni–Cr–B–Si–C alloys

This work reports the procedure for selection of alloying elements to refine the microstructure of hardfacing Ni–Cr–B–Si–C alloys by providing in situ formed nucleation agents. It is concluded that the refining element should be able to spontaneously produce precipitates at high temperatures with little solubility in their Cr-rich counterparts. After exploring the theoretical backgrounds on how to select the refining element, Nb and Zr were selected and the phase formation reactions of Zr- or Nb-modified Ni–Cr–B–Si–C alloys were calculated using Thermo-Calc® simulations. Detailed microstructural analyses of the rapidly solidified samples deposited from the modified alloys showed that addition of Nb in specific quantities induces a significant microstructural refinement in the original Ni–Cr–B–Si–C alloy without deteriorating its high hardness. The Nb-modified alloy could be used to further investigate the viability of microstructural refinement as an effective toughening mechanism for Ni–Cr–B–Si–C and similar alloy systems.     

应用电极涂层工艺生产1Cr12Ni2W1Mo1V电渣重熔钢

大冶特钢公司应用电极涂层的工艺方法，使碳或硅、锰成分偏低的电极材料在电渣重熔过程中减少这些元素的烧损，甚至提高含量，从而生产出成分完全合格的电渣重熔钢，应用于1Cr12Ni2W1MO1V耐热钢生产取得了良好的结果。     

Effects of inclusions on the precipitation of chi phases and intergranular corrosion resistance of hyper duplex stainless steel

During the initial stage of aging heat treatment at 850 °C, inclusions such as (Cr, Mn, Al) oxides and (Cr, Mn, Al, Fe) oxides of a hyper duplex stainless steel act as preferential precipitation sites for the chi phase like ferrite/austenite phase boundaries and ferrite/ferrite grain boundaries. The chi phase is precipitated around the inclusions due to the blocking and piling up the alloying elements such as Mo and W around the inclusions. The precipitation of Mo and W enriched chi phase around the inclusions decreases the intergranular corrosion resistance due to the formation of Mo and W depleted zones.     

Effect of Cr, Nb, Mn, V, W and Si on high temperature oxidation of TiAl alloys

Alloys of Ti−(47,51)Al, Ti47Al−4Cr, Ti48Al−2Cr2Nb, Ti47Al−1Mn, Ti39.4Al−10V, Ti48.4Al−1.9W, and Ti43Al−2W0.1Si were oxidized at temperatures between 800 and 1000 °C in air to determine the effect of each alloying element on oxidation behavior. Among the alloys tested, the Ti48.4Al-1.9W alloy displayed the best oxidation resistance, due to the beneficial effects of W, whereas the Ti39.4Al-10V alloy displayed the worst oxidation resistance, due to the formation of volatile V-oxides. Cr was harmful while Nb was beneficial. The oxidation rate of each alloy was not strictly proportional to temperature, because each alloying element had different temperature sensitivity with respect to oxidation rate.     

Effect of Alloying Elements on True-Stress True-Strain Flow Curves of Pearlitic Steel

The effects of additions of alloying elements on the true-stress, true-strain characteristics of 0.30 pet C, 1.00 pet Mn, 0.30 pet Si pearlitic steel were studied. The alloying elements investigated were C, Mn, Si, P, Ni, Cu, V, Mo, Cr, Al, B, S, and Ti. The alloys are compared on the basis of fracture stress, fracture strain, energy to fracture, rate of strain hardening, strain hardening exponent, height of the flow curve, and lower yield point.     

Microstructure and creep behavior of directionally solidified TiAl-base alloys

Tensile creep tests were conducted on directionally solidified TiAl alloys to discern the effect of alloying and lamellar orientation. A seeding technique was used to align the TiAl/Ti₃Al lamellar structure parallel to the growth direction for alloys of Ti–47Al, Ti–46Al–0.5Si–0.5X (X=Re, W, Mo, and Cr), and Ti–46Al–1.5Mo–0.2C (at.%). Tensile creep tests were performed at 750 °C using applied stresses of 210 and 240 MPa. Aligning the lamellar microstructure greatly enhances the creep resistance which can further be improved by additional alloying.     

碳化物形式对多组元铁合金高温摩擦磨损性能的影响

多组元铁合金耐磨材料主要应用于热轧辊,其磨损失效主要形式为高温钢坯与轧辊的相对运动造成.制备了4种不同成分的多组元铁合金,成分分别为0、1％、3％、5％的Mo,2.6％C、1％Si、5％Mn、7％V以及8％Cr,其余为Fe.使用HT1000高温摩擦磨损试验机在500℃条件下对该合金进行了磨损试验,采用XRD和SEM/E...     

First-principles prediction of partitioning of alloying elements between cementite and ferrite

At long tempering times in steels when both cementite (Fe₃C) and ferrite (body-centered cubic (bcc) Fe-rich solid solution) phases are present, alloying elements tend to segregate to either of the two phases. The elements V, Cr, Mn, Mo and W are found to partition to the cementite phase, while Al, Si, P, Co, Ni and Cu partition to ferrite. We show that partitioning of alloying elements and cementite (de)stabilization by alloying in mixtures of bcc Fe and cementite are intimately related through the introduction of a partitioning enthalpy. The formation enthalpy of alloying-element-substituted cementite is shown not to be a proper gauge for addressing these questions.     

Mechanical characteristics and microstructure of weld joint of high-temperature martensitic steel containing 9% Cr

The structure and mechanical characteristics of a weld joint of 10Kh9K3V2MFBR steel (0.097 C, 0.17.Si, 0.54 Mn, 8.75 Cr, 0.21 Ni, 0.51 Mo, 0.07 Nb, 0.23 V, 0.004 N, 0.003 B, 1.6 W, 0.15 Cu, and Fe for balance, wt %) have been studied; the joint was produced by hand welding in an argon atmosphere using 03Kh20N45M7G6B welding wire (0.3 C, 20 Cr, 45 Ni, 7 Mo, 6 Mn, and 1 Nb, wt %). The weld joint is divided into the zone of the base metal, a thermal effect zone, which consists of zones that contain fine and coarse original austenitic grains, and the zone of seam metal. It has been shown that the weld joint of 10Kh9K3V2MFBR steel possesses high strength characteristics at the room temperature under static loading and a satisfactorily impact toughness, which has the minimum value of 30 J/cm² in the zone of the seam metal and does not depend on the temperature. With a decrease in the temperature from the room temperature to 253 K, a ductile–brittle transition occurs in the thermal effect zone. Creep tests carried out at the temperature of 923 K have shown that the long-term strength of the weld seam is lower than that of the base material in the entire stress range being tested. At stresses of 140 MPa or higher, the acceleration of creep in the weld seam is observed, while at low stresses of about 120 MPa, the rates of creep in the weld seam and in the base metal remain similar until the transition to the stage of accelerated fracture occurs. The difference in the values of the long-term strength is due to premature fracture, which occurs in the thermal effect zone with the finegrained structure.