Showing papers on "Carbon steel published in 2007"

Effects of carbide size and Co content on the microstructure and mechanical properties of HVOF-sprayed WC–Co coatings

Abstract: Twelve commercially available WC–Co powders with different average WC grain sizes (0.2, 2, and 6 μm) and cobalt contents (8, 12, 17 and 25 wt.%) were sprayed on carbon steel substrates using High Velocity Oxy-Fuel (HVOF) spraying process. Hardness, Young's modulus, and fracture toughness of the coatings were measured. While the hardness and Young's modulus decreased with increasing cobalt content from 1600 to 1100 Hv and from 400 to 300 GPa respectively, the fracture toughness remained in the range from 4 to 6 MPam 1/2 . The coatings with 2 μm carbide showed lower hardness than those deposited from 0.2 and 6 μm carbide. These measured mechanical properties were discussed with the help of microstructures of the coatings investigated by scanning electron microscopy, X-ray diffraction and chemical analysis. Finally, the hardness of the binder phase in these coatings was estimated to range from 1000 to 1300 Hv by applying the mixture rule for composites to the experimental data, demonstrating that such hardening of the binder phase is a key factor affecting the mechanical properties of the coatings.

Cladding of WC–12 Co on low carbon steel using a pulsed Nd:YAG laser

Abstract: Laser cladding is an advanced material processing technology that has potential to deposit various materials locally on highly non-planar and complex surfaces. It can be used to refurbish or improve corrosion, wear and other surface related properties of components. The laser cladding of WC–Co using continuous wave (CW) laser has been tried and problems, like—cracks, porosity, poor bonding, partial melting of WC particles in the Co matrix, etc., have been observed. To resolve these issues, the successful laser cladding with alternate binder materials, like—Ni, Fe, Co–Cr, Ni–B–Si, etc., have been reported. In the present study, a pulsed Nd:YAG laser was used to deposit multi-layer overlapped cladding on low carbon steel substrate using dynamic powder blowing technique. Thus, produced laser cladding samples were subjected to various mechanical tests and metallurgical analyses. The results showed that fully dense and crack free clad surfaces of WC–Co with an excellent metallurgical bonding and low dilution were deposited. No melting of WC particles in the Co matrix was observed during the microscopy. The average microhardness at the clad surface was about 1350 HV, while that at substrate was 200 HV. The observed adhesion strength of the WC–Co cladding to the substrate was about 60 MPa.

Elastic constants and internal friction of martensitic steel, ferritic-pearlitic steel, and α-iron

Abstract: The elastic constants and internal friction of induction hardened and unhardened SAE 1050 plain-carbon steel at ambient temperatures were determined by resonant ultrasonic spectroscopy. The hardened specimen contained only martensite and the unhardened specimen was ferrite-pearlite. Using an inverse Ritz algorithm with assumed orthorhombic symmetry, all nine independent elastic-stiffness coefficients were determined, and, from the resonance peak widths, all nine components of the internal-friction tensor were determined. Similar measurements and analysis on monocrystalline α-iron were performed. The steel has slight elastic anisotropy, and the isotropically approximated elastic moduli were lower in the martensite than in ferrite-pearlite: shear modulus by 3.6%, bulk modulus by 1.2%, Young modulus by 3.2%, and Poisson ratio by 1.5%. Isotropically approximated elastic moduli of α-iron were 0.6–1.3% higher than ferrite-pearlite. All components of the internal-friction in martensite were higher than those of ferrite-pearlite, but lower than those of α-iron.

Corrosion Prevention and Protection: Practical Solutions

Abstract: Preface Acknowledgments PART I 1 Introduction and Principles of Corrosion 11 Impact of Corrosion 12 Preliminary Aspects of Thermodynamics and Kinetics 13 Nature of Corrosion Reactions 14 Oxidation and High-temperature Corrosion 141 Oxidation of Alloys 15 Corrosion Prevention 16 Design Factors 17 Life Prediction Analysis of Materials 18 Corrosion Protection References 2 Corrosion Testing, Detection, Monitoring and Failure Analysis 21 Corrosion Testing 22 Corrosion Detection and Monitoring 23 Failure Analysis References 3 Regulations, Specifications and Safety 31 Regulations and Specifications 32 Safety Considerations References 4 Materials: Metals, Alloys, Steels and Plastics 41 Cast Irons 42 Carbon and Low-alloy Steels 43 Stainless Steels 44 Aluminum and Aluminum Alloys 45 Copper and Copper Alloys 46 Nickel and its Alloys 47 Titanium and its Alloys 48 Cobalt Alloys 49 Lead and Lead Alloys 410 Magnesium and Magnesium Alloys 411 Zinc and Zinc Alloys 412 Zirconium and its Alloys 413 Tin and Tin Plate 415 Polymeric Materials References 5 Corrosion Economics and Corrosion Management 51 Corrosion Economics 52 Corrosion Management 53 Computer Applications References PART II 6 The Forms of Corrosion 61 Corrosion Reactions 62 Corrosion Media 63 Active and Active-Passive Corrosion Behavior 64 Forms of Corrosion 65 Types and Modes of Corrosion 66 The Morphology of Corroded Materials 67 Published Corrosion Data References Bibliography 7 Practical Solutions 71 Cathodic Protection of Water Mains Bibliography 72 Internal Corrosion of Aluminum Compressed Air Cylinders Bibliography 73 Some Common Failure Modes in Aircraft Structures 74 Premature Failure of Tie Rods of a Suspension Bridge 75 Corrosion and Lead Leaching of Domestic Hot and Cold Water Loops in a Building References 76 Cathodic Protection of Steel in Concrete Bibliography 77 Corrosion of Aluminum Components in the Glass Curtain Wall of a Building References 78 Corrosion in a Water Cooling System 79 Pitting Corrosion of 90/10 Cupronickel Chiller Tubes Bibliography 710 Weld Metal Overlay: a Cost-effective Solution to High-temperature Corrosion and Wear Problems Bibliography 711 Equipment Cracking Failure Case Studies 712 Failure of a Conveyor Drive Shaft 713 Failure Analysis of Copper Pipe in a Sprinkler System 714 Failure of Rock Bolts References 715 Failure Analysis of 316L Stainless Steel Tubing of a High-pressure Still Condenser References 716 Failure of a Landing Gear Steel Pin Reference 717 Hydrogen-induced Cracking References 718 Micromechanisms of Liquid and Solid Metal-induced Embrittlement References 719 Nitrate SCC of Carbon Steel in the Heat Recovery Steam Generators of a Co-generation Plant References 720 Performance of Stainless Steel Rebar in Concrete Bibliography 721 Corrosion of an Oil Storage Tank References 722 Corrosion of a Carbon Steel Tank in a Phosphatizing Process 723 Underground Corrosion of Water Pipes in Cities 724 Corrosion in Drilling and Well Stimulation References Index

Experimental investigation of cold-formed steel material at elevated temperatures

Abstract: This paper presents the mechanical properties data for cold-formed steel at elevated temperatures. The deterioration of the mechanical properties of yield strength (0.2% proof stress) and elastic modulus are the primary properties in the design and analysis of cold-formed steel structures under fire. However, values of these properties at different temperatures are not well reported. Therefore, both steady and transient tensile coupon tests were conducted at different temperatures ranged approximately from 20 to 1000 °C for obtaining the mechanical properties of cold-formed steel structural material. This study included cold-formed steel grades G550 and G450 with plate thickness of 1.0 and 1.9 mm, respectively. Curves of elastic modulus, yield strength obtained at different strain levels, ultimate strength, ultimate strain and thermal elongation versus different temperatures are plotted and compared with the results obtained from the Australian, British, European standards and the test results predicted by other researchers. A unified equation for yield strength, elastic modulus, ultimate strength and ultimate strain of cold-formed steel at elevated temperatures is proposed in this paper. A full strain range expression up to the ultimate tensile strain for the stress–strain curves of cold-formed carbon steel at elevated temperatures is also proposed in this paper. It is shown that the proposed equation accurately predicted the test results.

Steel to aluminium key-hole laser welding

Abstract: The laser joining of a low carbon steel to a 6000 series aluminium alloy was realised in key-hole welding mode in a steel-on-aluminium overlap configuration and was investigated in a three-fold approach: (1) process optimisation, (2) material characterisation and (3) mechanical testing. No-defect welds, composed of a solid solution of aluminium in iron and richer aluminium “white solute bands” of FeAl phases were obtained when limiting steel penetration in aluminium to below 500 μm. Embrittlement of the joining zone was observed, mainly located on the weld–aluminium interfaces composed of Fe2Al5 and/or FeAl3 phases with thicknesses between 5 μm and 20 μm. Limiting penetration to below 500 μm allowed to restrict steel to aluminium dilution in order to confine the hardness of the welds. With such penetration depths, up to 250 N/mm in linear strength could be achieved, with failures located in the weld–aluminium interfaces. Increasing penetration depth led to a change in the assembly weak points (in the weld and on the steel–weld interfaces) and induced a severe decrease in strength.

Corrosion protection of carbon steel by an epoxy resin containing organically modified clay

Abstract: This study focusses on the use of montmorillonite clay (MMT) treated with an organic compound (aminotrimethylphosphonic acid (ATMP)) and dispersed in an epoxy resin to improve corrosion protection of carbon steel. X-ray diffraction was performed to verify that the individual silicate layers were separated and dispersed in the epoxy resin. Corrosion resistance of the coated steel was evaluated by electrochemical impedance spectroscopy (EIS) and local electrochemical impedance spectroscopy (LEIS). Three systems were tested: the epoxy clear-coat, the epoxy resin containing 2 wt.% clay and the epoxy resin containing 2 wt.% clay modified byATMP (ATMP-modified clay). From conventional EIS, it was shown that the incorporation of clay or ATMP-modified clay in the epoxy matrix significantly improved the barrier properties of the coating. The corrosion resistance of the carbon steel coated by the epoxy resin containing ATMP-modified clay was higher than that obtained for the system containing non-treated clay. Local electrochemical measurements performed on scratched samples revealed the inhibitive role of ATMP at the carbon steel/coating interface.

Generation of aluminium–steel joints with laser-induced reactive wetting

Abstract: A new mean of assembling steel to aluminium was developed, following previous work by German workers [1] . In this new method, a laser-induced aluminium melt pool spreads and wets a solid steel, to generate, after solidification a sound and resistant interface layer. Joint properties were investigated, in terms of surface aspects, interface microstructures and mechanical resistances under tensile testing, for non-galvanized and galvanized DC04 steels. Thermal and diffusional finite element (FE) simulations were also carried out to calculate temperature history at interfaces, and reaction layer thickness. The 2–20 μm thick reaction layers formed all along the interface were found to be mostly composed of Fe 2 Al 5 intermetallic compound with a high hardness (1200 HV) and rather low ductility (presence of solidification cracks). The presence of a 10 μm thick Zn layer on the steel was shown to have a beneficial influence on the wetting characteristics of the joint, despite the formation of occluded pores in the melt pool due to Zn vaporisation. FE thermal modelling evidenced 760–1020 °C wetting temperatures at the interface between DC04 low carbon steel and 6016 aluminium sheets, with time maintains of the melt pool in the 0.2–0.5 s range, resulting in high-speed reaction kinetics. Using these temperature data, diffusion calculations were shown to provide a rather good prediction of intermetallic thicknesses. Tensile tests were considered on aluminium–steel lap joints and evidenced higher mechanical resistances (220 N/mm linear tensile strength) on galvanized steels, provided that fluxing of the steel surface was carried out prior to welding to avoid zinc vaporisation. Comparatively, non-galvanized assemblies exhibited much lower mechanical resistances (170 N/mm resulting in a 90 MPa interfacial shear strength). It was concluded that the laser-induced wetting technique is a rather effective way for generating Al-steel joints without filler material, and that it should be considered as a competitive technique versus solid assembly modes (friction stir welding …).

Experimental studies of the interactions between anaerobically corroding iron and bentonite

Abstract: In the horizontal emplacement concept (KBS-3H) for the disposal of radioactive waste, which is being developed in Sweden and Finland, copper canisters will be surrounded by bentonite buffer and placed in perforated steel containers in long horizontal boreholes in the crystalline bedrock, at a depth of ≈500 m. Under the chemical conditions in a deep repository, it is possible that the release of iron from the steel containers could influence the physico-chemical properties of the bentonite, for example, by exchange of the interlayer ions. In order to gain further insights into this process, an experimental study was undertaken, to investigate the mode of iron uptake into bentonite and the extent of changes induced in the basic physico-chemical properties of bentonite. The samples were taken from long-term anaerobic corrosion tests of carbon steel or cast iron in compacted bentonite (Na/Ca-bentonite: Volclay MX-80, ∼4% Fe 2 O 3 ) in contact with a simple artificial groundwater at 30 °C or 50 °C. A range of analytical techniques was applied to samples of corrosion product on carbon steel and cast iron and to the bentonite surrounding the corroding specimens. Corrosion products and bentonite samples were analysed using scanning electron microscopy (SEM), electron microprobe analysis (EPMA), Raman spectroscopy, X-ray diffraction (XRD) and Mossbauer transmission spectroscopy. In addition, the bentonite samples were analysed using Fourier transform infra-red spectroscopy (FTIR), transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS) and selected area electron diffraction (SAED), exchangeable cation analysis and cation exchange capacity (CEC) measurements. Hydraulic conductivity and swelling pressure were also measured. From visual observation, the corrosion product formed on the carbon steel in bentonite was less voluminous than that formed on steel in artificial porewaters with no bentonite, although previous work showed that the corrosion rates were slightly higher in the presence of bentonite. The Raman spectroscopy analysis showed that corrosion products on the surface of carbon steel and cast iron consisted of an inhomogeneous mixture of magnetite, hematite and goethite. The predominant species was magnetite. In the bentonite, the concentration of iron decreased with increasing distance away from the iron–bentonite interface, with local iron concentrations as high as 20 wt% in some experiments. The total iron content of the bentonite in contact with corroding carbon steel wires increased by several percentage points during the experiments and the cation exchange capacity of the bentonite was reduced. After contact with corroding steel wires the hydraulic conductivity of MX-80 increased substantially. The results of the analyses were consistent with ion exchange of Fe 2+ ions with Na + ions in the montmorillonite interlayer positions but the exact chemical location of all the additional Fe 2+ ions is currently uncertain. There was no evidence for the transformation of montmorillonite to an iron-rich clay mineral phase.