Stainless Steel Strip Research Articles

Effects of Particle Size Distribution on the Properties of Alumina-Zirconia-Graphite Refractory.

Alumina-Zirconia-Graphite (AZG) refractory is one of the most important refractory for AISI 304 stainless steel strip casting, especially used as slide gates or nozzles. A suitable particle size distribution desired by simple R(c/m) values, weight of coarse Al2O3 (500-1000μm)/weight of medium Al2O3 (61-125μm), is important for controlling the apparent porosity, which affects the thermal shock resistance and erosion resistance as well. The size modulus, R(c/m), has been shown to be a useful parameter for the evaluation of particle packing, as controlled by the particle size distribution, on various properties of the Alumina-Zirconia-Graphite refractory. The lowest apparent porosity (5%) and highest bulk density (3.5g/cm3) were obtained at R(c/m) value of 6.0. The relation of bulk density (D) with R(c/m) can be represented by D=-0.040R2 (c/m)+0.351R(c/m)+2.741 for R(c/m) 0.4 to 3.7, and D=-0.006R2(c/m)+0.080R(c/m)+3.272 for R(c/m) 3.7 to 13, respectively. The average pore size (Ps) with R(c/m) value is expressed as Ps=0.035R2(c/m)-0.554R2(c/m)+7.138. The average pore size (Ps) of AZG refractory decreased from 6.5μm to 3.1μm, as the R(c/m) increased from 0.4 to 6.0. The number of air exposure cycles for the thermal shock resistance (Rst) were 14-17, and the relation of thermal shock resistance with R(c/m) is correlated by Rst=0.160R2(c/m) -1.371R(c/m)+16.860 for R(c/m) 0.4 to 3.7, and Rst=0.007R2(c/m)+0.277R(c/m)+13.082 for R(c/m) 3.7 to 13, respectively. The thermal shock resistance decreased gradually as the R(c/m) value was increased from 0.4 to 3.7. The effect of apparent porosity (Po) on the erosion fraction (Er) is expressed by Er=0.233 Po+1.204.

SmartCart is low‐cost AGV

Inductive guidance system for the SmartCart AGV allows very fast installation and re‐layout using adhesive stainless steel strips on the floor. Vehicles are self‐contained and can be individually programmed. The manufacturer gains its experience in AGVs through contract manufacture and has now designed its own system.

Tool life equation for blanking 18-8 stainless steel strips

Hereinafter it is presented a model for the behaviour and life of circular blanking tool used in sheet forming processes of 18-8 stainless steel (sheet thickness: 1 mm). Firstly it has analyzed the different studies that have previously delt with this problem. Secondly taking into account recently made experiments, it is proposed a simple formulation to predict tool life with enough reliability. To this purpose it has examined different parameters in the wear process, inferring from these the fundamental parameters that regulate them and about which the different equations have been configurated. Blanking tests were performed using a 20 t press at a speed of 150 strokes/min. Punch materials used in these tests were AISI A2 and AISI D2 with diameters between 1.5 and 10 mm. The blanking tests were performed at a clearance between 5 and 20 % of the work material thickness.

The electrochemical behaviour of direct strip casting stainless steel in acid solutions

The electrochemical behaviour of direct strip casting (DSC) 304 stainless steel in 0.1 M H2SO4 and 0.01M HCl solutions was investigated. The DSC 304 stainless steel strips were produced by using either copper-alloy roller or 304 stainless steel roller. The difference in thermal conductivity of different roller materials resulted in a change in the surface microstructure of the DSC strips. Potentiodynamic polarization curves of the DSC 304 stainless steels produced were measured in 0.1M H2SO4 and 0.01M HCl solutions. The results showed that both alloys could passivate in the above solutions. In the HCl solution, the passive potential range of DSC 304 stainless steel with a higher ferrite content prepared by the copper roller was wider than that with a lower ferrite content. Furthermore, the addition of silicon could cause an expansion while the addition of titanium could lead to a shrinkage in the passive range in 0.01M HCl solution. Potential decay tests in 0.1M H2SO4 solutions showed that the reactivation time decreased as the ferrite content was increased. © 1998 Chapman & Hall

Transmission electron microstructures of stainless steel strip overlay joints

Transmission electron microstructures of stainless steel strip overlay joints

Transmission electron microstructures of stainless steel strip overlay joints

The microstructural alterations and transformations in the as welded condition and after post-weld heat treatment (PWHT) around the transition zones of 2.25Cr-1Mo steel with stainless steel strip overlay joints were observed mainly by transmission electron microscopy (TEM). In an as welded joint, the microstructural changes from the overlay weld metal across the transition zone to the base metal were: austenite plus some δ ferrite and deformation twins of weld metal-austenite( A) /martensite(M) weld interface-martensite layer-granular bainite of heat affected zone (HAZ)- ferrite plus granular pearlite of base metal. Across the PWHT joint, the general microstructural variations were similar to those across the as welded joint. However, some major morphological transformations had occurred: carbides had precipitated along the austenite/∆ ferrite grain boundary of the overlay; carbides had precipitated in the overlay weld metal zone adjacent to the A/M interface; carbides had precipitated in the martensite layer; and there was a new martensite/ferrite (of the carbon depleted zone) weld interface. These results may be useful in understanding the disbonding mechanism of this type of joint.

Electroslag and submerged arc stainless steel strip cladding

Stainless steel strip cladding is a flexible and economical way of depositing a corrosion resistant, protective layer on a load‐bearing mild or low alloy steel. Strip cladding is therefore widely used in the production of components for the chemical, petrochemical and nuclear industries, for example.

Characteristics and Production Mechanism of Sulfuric Acid and Nitric-Hydrofluoric Acid Pickling Sludge Produced in Manufacture of Stainless Steel.

Stainless steel pickling sludge consists largely of surface scale from stainless steel strips, being composed mainly of Cr oxides. Moreover, the present work shows that the Cr concentration of the sludge is approximately twice that of ordinary stainless steels. The particle size of sulfuric acid sludge is 0.325 μm, while that of nitric-hydrofluoric acid sludge is 9.2 μm. Nitric-hydrofluoric acid sludge tends to coagulate in a relatively short time, while sulfuric acid sludge essentially does not tend to coagulate. The main components of sulfuric acid sludge and nitric-hydrofluoric acid sludge are FeCr2O4 and Cr2O3. In the mechanism of sludge precipitation in the pickling process, acid penetrates cracks in the scale and dissolves part of the scale and the substrate. The undissolved scale then loses the ability to bond with other scale and the substrate and settles out in the pickling tanks.

Study of the oxide layer formed on stainless steel exposed to boiling water reactor conditions by ion beam techniques

The build-up of the oxide layer on austenitic steel under boiling water reactor (BWR) conditions was studied by macro- and micro-Rutherford backscattering spectrometry (RBS) and sputtered neutral mass spectroscopy (SNMS). RBS is applicable when the oxide thickness is larger than 20 nm and yields both the layer thickness and its stoichiometry. SNMS provides elemental depth profiles and the oxide thickness when combined with profilometry. Stainless steel strip samples pre-treated (electro- or mechanically polished) or not, exposed in a loop simulating the BWR-conditions for periods ranging from 31 to 291 days and with a low water flow velocity show oxide layers with a thickness of about 300 to 600 nm. There is no significant increase of the oxide layer thickness after 31 days of exposure. The paper confirms the presence of inner and outer oxide layers and also confirms the stoichiometry M 2O 3 in the external part in contact with the oxygenated water. The oxide layer consists not only of an outer layer and an inner layer but also of a deep apparent oxide/metal interface that is attributed to oxide formation through the steel grain boundaries.

The effects of surface corrosion on the fatigue behaviour of aluminium alloy specimens containing cold expanded holes : Glinos, N., Wagstaff, P.G. and Cook, R. Computational Methods Testing for Eng. Integrity (1996) 61–70 Conference: First International Conference on Computational Methods and Testing for Engineering Integrity, Kuala Lumpur, Malaysia (19–21 Mar. 1996)

The paper details experimental research on the surface modification/alloying and combined electrical discharge texturing (EDT) of hardened AISI D2 Sendzimir rolls, used for the production of stainless steel strip. Test results are presented when using powder metallurgy (PM) green compact and sintered electrodes—TiC/WC/Co and WC/Co, as a means to improve roll life and performance. Two- and three-dimensional surface roughness assessments showed the topographical characteristics of EDT samples processed using PM electrodes, to be similar to those found when using conventional copper or graphite tools, with the same pulse generator parameters. GDOES analysis showed that Ti and/or W contained in the PM electrodes, together with C decomposed from the dielectric medium during sparking, were transferred to the workpiece surface. Microhardness measurement of roll cross-sections indicated an increase in white layer hardness of ∼300 HK (0.025) when employing sintered TiC/WC/Co tools, compared with conventionally processed EDT rolls. In rolling trials using mill rolls textured with PM tool electrodes, roll/strip texture transfer measures (Ra and Pc), were consistently higher for the TiC/WC/Co textured rolls, indicating less roll wear.

Corrosión en soldaduras de aparatos de ortodoncia

The study of corrosion-related problems of dental materials has undergone a considerable development in recent years in order to avoid the use of materials with insufficient corrosion resistance in patients' mouth. The subject of the present work was to study a particular type of corrosion: galvanic corrosion. One of the most common case of galvanic couples in patients' mouth are the orthodontic appliances. The materials studied in the present work were stainless steel strips and silver-copper wires, isolated and welded between them. The electrochemical tests were performed in a NaCl 0.1M and Lactic Acid 0.1M solution (pH 2.3), and after test, the specimens were observed using the optical and scanning electron microscope. The results show that when stainless steel is coupled with a silver solder, the last is the anode of the galvanic couple. As a consequence of this, the silver solder undergone a severe attack. Stainless steel orthodontic appliances with silver solder are feasibly destroyed due to a severe attack on the filler metal disjoining the welded parts.

Criterion for tool wear limitation on blanking 18-8 stainless steel strips

The present article shows a wear limiting criterion for 18-8 stainless steel punching process. For this reason, different factors such as length of the tool, clearance or materials, have been considered in order to obtain the number of possible strokes between grindings and the total number of blanks until a complete total failure. Finally, the maximum number of possible strokes which it will give the economically accepted wear can be obtained. The results obtained by the present method are in good agreement with the previous experimental and theoretical work. Blanking tests were performed using a 20 t press at a speed of 150 strokes/min. The punching material used in these tests was AISI A2 with diameters between 6 and 14 mm. The blanking tests were performed at a clearance between 5 and 20 % of the thickness of the work material.

Effect of micro-defects on the surface brightness of cold-rolled stainless-steel strip

Cold-rolled stainless-steel strip can be produced efficiently by high-speed rolling in a cluster-type rolling mill with small-diameter work rolls, or in a tandem cold-rolling mill with large-diameter work rolls. The surface brightness of the strip is deteriorated by high-speed rolling, and the surface brightness of a strip rolled by large-diameter work rolls becomes worse than that of a strip rolled by small-diameter work rolls. In this study, the effect of micro-defects on surface brightness is examined with laboratory-scale and actual rolling mills, and the mechanisms for the occurrence of micro-pits in cold rolling are discussed. The surface brightness was affected strongly by micro-defects on the surface, the brightness being improved for decreasing surface-area ratio of the micro-defects. Micro-defects can be reduced to four types: micro-pits originating from the surface roughness of the mother sheet; oil-pits formed during cold rolling; grooves formed by inter-granular corrosion during pickling; and scratches due to the surface roughness of the rolls. The micro-pits remaining on the surface of cold-rolled sheet were affected by the diameter of the work rolls, the surface roughness of the mother sheet, and the rolling reduction. The effects of rolling speed and of the viscosity of the rolling oil were minor under the experimental conditions investigated.

Development of quench protection heaters for superconducting solenoids

Our approach to applying quench heaters to epoxy impregnated coils is to encapsulate the heaters within the epoxy and glass on the coil circumference. The mechanical integrity of the epoxy and glass in the neighbourhood of the heater is critical. The interface is subject to large temperature gradients and mechanical stress during operation of the protection system. Characterization of this interface allows the reliable design of heater networks on large epoxy impregnated coils. The heater is a thin stainless steel strip located axially on the outside of the coil. The geometry may be further complicated by the presence of steel over-banding on the coil perimeter. We have fabricated models demonstrating heater interfaces with and without overbanding. We characterize the interface using a damage threshold concept in the context of cyclic life testing on the interface. This paper reports the results from cyclic life testing in liquid helium.

液体ヘリウムにおける水平被覆ストリップからの急速過渡沸騰熱伝達

To make a thermal stability analysis of superconducting magnets, fundamental data on rapid transient boiling heat-transfer giving consideration to the influence of electrically insulated film are needed. In order to simulate an insulated superconductor in practical use, a 20-μm-thick stainless steel strip was applied as the test heater surface in this study. Both surfaces of the strip were coated with a PVF and carbon-paste films. Steady-state and rapid transient boiling heat-transfer were studied utilizing stepwise heat input from the test piece, which was placed horizontally in saturated liquid helium-4. In steady-state boiling, the thermal resistance of the coatings suppressed burn-out and quick transition. Consequently, the heat-transfer data correlated well with a single boiling curve having smooth and continuous transition from nucleate boiling to film boiling. The boiling heat-transfer characteristics are separated into three regions by the steady-state critical flux (CHF) of upward and downward-facing heaters. The nucleate boiling heat-transfer was almost the same as that of the vertically-placed heater reported previously by the authors, but the transition and film boiling heat-transfer were lower. When a stepwise heat flux higher than the steady-state CHF for the downward-facing heater was applied, the wall heat flux sharply dipped once just after the transition from transient nucleate boiling to film boiling. The heat conduction and transient nucleate boiling heat-transfer were almost the same as that of the vertically-placed heater. In contrast, heat-transfer after the transition to film boiling was lower.

オーステナイト系ステンレス鋼板表面の粒界浸食溝の冷間圧延における平滑化挙動

オーステナイト系ステンレス鋼板表面の粒界浸食溝の冷間圧延における平滑化挙動

Characterization of TiN films deposited onto stainless steel strips by continuous dry-coating process

This paper constitutes the second and final part of a work aimed at characterizing TiN coatings obtained by different physical vapor deposition techniques, namely, ion plating, sputtering, and electron beam, utilized as continuous processes. The results of characterization indicated that the properties of the coatings are affected by the deposition techniques. Significant differences were observed in texture, morphology, chemical composition, adhesion, and other features of the coatings obtained by electron beam technology compared to those obtained by sputtering and ion plating.

Development of a fast annealing pickling technology for cold rolled stainless steel strips

A new heating technology using a combustion furnace with impinging flame burners has been developed for annealing cold rolled stainless steel strips. This technology not only improves the efficiency of the annealing, but also facilitates the descaling after annealing.The rapid heating of TP304 stainless steel with the burners, followed by the short soaking, enables us to get a thinner scale which can be dissolved easily by the anodic electrolysis in a sodium sulphate solution and subsequent immersion in nitric-hydrofluoric acid solution. Stainless steel strips of 1 mm gauge are now produced at a rate of about 70-80 m/min.

Influence of Creq/Nieq ratio on solidification structures and tensile properties of strip cast austenitic stainless steels

Seven samples of austenitic stainless steel strip about 1.5 mm thick were produced by the strip casting process. The Creq/Nieq ratio of the stainless steel strips was varied from about 1.23 to 1.95...

Flame Generation of Two New Precursors of Vanadyl Pyrophosphate

Two new vanadyl pyrophosphate precursors were produced in a single step operation using a counterflow diffusion flame burner. The technique consists of adding a vanadium and a phosphorus halide to the fuel stream of hydrogen–oxygen flames. Particles nucleate and grow in the flame to an average diameter between 5 and 30 nm. Upon exiting the flame, powders are collected on two stainless steel strips and their crystalline structures are analyzed by x-ray diffraction and Fourier-transform infrared spectroscopy. A strong effect of flame temperature on the crystalline structure of the powders produced is observed. When a high temperature flame is used, the powder collected is a mixture of VOPO4· 2H2O and (VOPO4)1−x(VOHPO4)x·2.6H2O. This mixture forms γ-VOPO4upon subsequent reheating at 750°C in a oxidizing atmosphere, and transforms into (VO)2P2O7in an oxygen-free atmosphere at 700°C. When a lower temperature flame is used, the powder collected is (VOPO4)1−x(VOHPO4x·2.9H2O, which transforms at 750°C into β-VOPO4in an oxidizing atmosphere and to (VO)2P2O7at 700°C in an oxygen-free atmosphere. Structural differences between the two vanadyl pyrophosphates are observed. These differences are discussed in terms of the ability of (VO)2P2O7to accommodate various disordered and polytypic structures.