Showing papers on "Carbon steel published in 1988"

Anti-microbial composition

Abstract: Medical instruments, which may include brass, copper, aluminum, stainless steel, carbon steel, or plastic parts are sterilized or disinfected in an anti-microbial solution. The anti-microbial effect of a strong oxidizing agent, such as peracetic acid, is improved with a wetting agent. The solution further includes a triazole or other component for inhibiting the corrosion of copper and brass. Phosphates or other buffering agents adjust the oxidizing agent generally to a neutral pH for preventing the corrosion of steel. Molybdates or analogous compounds also buffer the pH and inhibit corrosion of aluminum by the oxidizing agent. The corrosion inhibiting is enhanced by the wetting agent. Optionally, a sequestering agent is provided for inhibiting hard water precipitation.

Corrosion inhibition study of a carbon steel in acidic media containing hydrogen sulphide and organic surfactants

Abstract: Inhibition of the corrosion of a carbon steel (0.4% C) by 2-hexadecyl imidazoline and 2-hexadecyl imidazole has been evaluated by electrochemical techniques and correlated with surface tension measurements. Plots of inhibitor efficiency versus surfactant concentration produce S-shaped curves which are assumed to represent adsorption isotherms. A sharp increase in slope was observed at concentrations below the critical micellar concentration. This increase in slope is accounted for by changes in conformation of the adsorbed molecules: horizontal orientations (with respect to the surface) at lower concentrations reflecting cathodic behaviour and perpendicular orientations at the higher concentrations reflecting mixed cathodic and anodic behaviour. At increasing concentrations the inhibitory effect remained constant, suggesting complete saturation of the surface in a bilayered arrangement. Electrochemical impedance measurements, carried out for concentrations greater than the critical micellar concentration, corroborate this assumption: the inhibitors form a thick but adherent micellar film which acts as a diffusion barrier.

Magnetic and metallurgical properties of high-tensile steels

Abstract: An investigation into the relation between magnetic and metallurgical properties of 26 types of high-strength constructional steel is reported. Correlation between chemical composition and coercive field was found. An independent correlation between coercivity, grain size and relative pearlite and ferrite fractions was also found. The coercivity and initial permeability varied with ultimate tensile strength but Vickers hardness measurements were not found to be a reliable method of predicting coercivity over the hardness range found in the sample set. For a larger hardness range, produced by heat treating one steel type, an excellent linear relationship was found between hardness and coercivity.

Analysis of Carbon Steels Affected by Bacteria Using Electrochemical Impedance and Direct Current Techniques

Abstract: The failure of metal structures in contact with natural, untreated waters is frequently ascribed to bacterial corrosion. This study compares the corrosive effects of Vibrio natriegens (V.natriegens) when in batch and continuous flow culture. Evidence is presented for enhanced corrosion of carbon steel resulting from “aerobic” culture of V.natriegens with two sulfate-reducing bacteria (SRB). The corrosion processes are quantified and, to some degree, described by nondestructive electrochemical impedance and direct current (DC) polarization techniques. The V.natriegens/SRB co-culture is shown to induce a faster corrosion rate of carbon steel than V.natriegens alone or under sterile conditions. Batch culture-permitted a faster corrosion rate than continuous flow systems. When continuous flow conditions were allowed to lapse into stagnation (batch culture), however, the highest corrosion rate was observed. This confirms practical experience in which metal failure caused by bacteria is often correlate...

Stress Corrosion Cracking of Inconel Alloys and Weldments in High-Temperature Water — the Effect of Sulfuric Acid Addition

Abstract: The stress corrosion cracking (SCC) susceptibilities of Alloys 600 and 690, AISI 316 NG stainless steel (SS), ASTM A508 carbon steel, and a number of compatible weld metals have been evalu...

Influence of heating rate on the laser surface hardening of a medium carbon steel

Abstract: The finite difference method was applied to analyse the influence of heating rate on the transformation phenomenon in laser surface hardening of a medium carbon steel. The implicit scheme of this method was adopted to improve the accuracy of the numerical analysis since the very high heating and cooling rate and the small hardened zone, which characterize the process investigated, need a very detailed mesh generation. The calculated cooling rate was high enough for all the material that undergoes transformation into austenite to be transformed into martensite. From the calculated temperature change the heating rate of the transformation zone boundary could be estimated to be of the order of 104 °C s-1, which causes a delay in the austenite transformation and consequently a shift in the transformation temperature. Considering a heating rate of 104 °C s-1, the As (start of austenitic transformation) temperature of the investigated medium carbon steel with 0.45 wt.% C should be approximated to be about 830 °C and the Af (finish of austenitic transformation) temperature about 950 °C. Experimental results obtained by irradiating the test specimen with a 1 kW CO2 laser showed better agreement with the hardened zone sizes predicted by the modified As temperature than with those predicted by the equilibrium As temperature. From simulations it appeared that the occurrence of surface melting and the size and shape of the hardened zone are strongly dependent on process parameters such as beam spot diameter and traverse speed.

Effect of cyclic frequency on the fatigue life of ASME SA-106-B piping steel in PWR environments

Abstract: Fatigue life tests in pressurized water reactor (PWR) environments were performed on smooth and sharply notched specimens of ASME SA-106-B piping steel at cyclic frequencies of 1.0 Hz, 0.1 Hz, and 0.017 Hz. On the basis of these tests, it was concluded that no effect of cyclic frequency existed for smooth specimens whereas a frequency of 0.017 Hz proved to have the most detrimental effect on the cyclic life of the notched specimens. However, a reduction in fatigue strength in the low cycle fatigue regime and a fatigue strength enhancement in the high cycle regime was observed in both 288° C (550° F) air environment tests and PWR environment tests. This is believed to be due to dynamic strain aging processes. As a result, the current ASME Section III design curve for carbon steels is nonconservative in its positioning, which may decrease the presumed safety factor against fatigue failures in carbon steel piping components having structural discontinuities.

Ball-and-roller bearing system

Abstract: A rolling bearing, comprising an inner race, an outer race and rolling members which roll therebetween, at least one of the inner and outer races being subjected to carburizing and heating treatment, is characterized in that: the one race comprises a carbon steel containing 0.1 to 0.7 wt. % of carbon, with the residual austenite content on the track surface layer being 20 to 45 vol. % and the rolling members comprise a carbon steel containing 0.7 to 1.1 wt. % of carbon having carbonitriding and heating treatment applied on the surface layer, with the residual austenite content in such surface layer being 20 to 45 vol. % and the carbonitride in such surface being 3 to 15 vol. %. In another form of the bearing, the rolling members may comprise a carbon steel containing 0.1 to 0.7 wt. % of carbon, with the surface layers thereof being subjected to carburizing and heating treatment and having a residual austenite content of 20 to 45 vol. %.

CO2 Corrosion of Carbon Steel and 13Cr Steel in Particle-Laden Fluid

Abstract: Corrosion tests were conducted on carbon steel (API 5L X70) and 13Cr steel (AISI 420) materials in a 3% NaCl solution containing sand particles (5000 to 9000 ppm) and saturated with CO2 at defined partial pressure (0 to 0.3 MPa) and temperature (30 to 60 C). The effect of residual O2 content (10 to 1500 ppb) was further examined. The following two flow geometries were studied: (1) undisturbed pipe flow and (2) submerged jet impinging (30 to 90 degrees) onto a flat plate. The effect of specimen surface treatment (shot blasting or pickling) was examined with dry-polished material as a reference. Weight loss and electrochemical measurements were applied to determine average and instantaneous corrosion rates respectively. The results are discussed relative to fluid flow conditions and the surface preparation/microstructure of the materials tested. No stable corrosion product layers retarding CO2 corrosion were formed within the testing time frame (<100 h). Consequently, no erosion-corrosion associate...

Fire-side corrosion in refuse-fired boilers

Abstract: This paper reviews corrosive conditions in refuse-fired boilers and describes laboratory tests that define the relative corrosiveness of salts found in boiler deposits. Constituents of the salt mixtures tested include ZnCl/sub 2/, PbCl/sub 2/, FeCl/sub 2/, NaCl, KCl, ZnSO/sub 4/, PbSO/sub 4/, Na/sub 2/SO/sub 4/, and K/sub 2/SO/sub 4/. The corrosiveness of the salt mixtures was determined by measuring the corrosion rates of SA-178 Grade C carbon steel and SA-213 TP-304 stainless steel (SS) at 500 and 1050 F (260 and 566 C). The tests were 720-h long. The tests identified corrosive species and mechanisms that may be operative in refuse-fired boilers. At 1050 F (566 C), lead is extremely corrosive to the SS. Mixtures of NaCl + KCl, previously thought to be noncorrosive to furnace-wall tubes at 500 F (260 C), become corrosive (especially to SS) when they mix with FeCl/sub 2/, which forms as a corrosion product on steel surfaces. Carbon steel at a furnace-wall tube temperature of 500 F (260 C) is attacked most rapidly by salt mixtures containing ZnCl/sub 2/. Sulfates appear to inhibit these corrosion processes somewhat.

The influence of size and morphology of eutectoid carbides on the magnetic properties of carbon steels

Abstract: A study of the effects of adding carbon and changing its distribution within ferritic steels is reported. The magnetic properties of these steels were greatly affected by the amount of carbon and the size and morphology of the carbides. A correlation between initial permeability μin and coercivity Hc was determined from the results, which was found to be independent of the carbide morphology.

Structure and microhardness of laser-hardened 1045 steel

Abstract: Observations are reported on the effect of continuous CO2 laser irradiation on the structure and microhardness of AlSI 1045 steel. In the case of isolated beam passes, martensite formed in the melt zone and in former pearlite regions of the austenitization zone exhibits very high Vickers hardness values (HV 750 and 900, respectively). However, in the case of contiguous or partly overlapping passes a zone of tempered martensite with hardness down to HV 400 forms behind each pass, thus resulting in a seesaw hardness distribution across the processed surface. It has been found that a drastic decrease in the size of the laser-affected region occurs when the beam power density exceeds a certain threshold level.

Ignition of steel alloys by impact of low-velocity iron/inert particles in gaseous oxygen

Abstract: The ignition of carbon steel and 316 and 304 stainless steels caused by the impact of low-velocity particles (a standard mixture consisting of 2 g of iron and 3 g of inert materials) in gaseous oxygen was investigated using NASA/White Sands Test Facility for the ignition test, and a subsonic particle impact chamber to accelerate the particles that were injected into flowing oxygen upstream of the target specimen It was found that the oxygen velocities required to ignite the three alloys were the same as that required to ignite the particle mixture Ignition occurred at oxygen velocities greater than 45 m/sec at 20 to 24 MPa and was found to be independent of pressure between 2 and 30 MPa Comparison of the present results and the past results from Wegener (1964) with the Compressed Gas Association (CGA) oxygen velocity limits for safe operations indicates that the CGA limits may be excessively conservative at high pressures and too liberal at low pressures

Method of welding inside a groove machined in a solid steel part, and utilization of the method for repairing a cracked rotor

Abstract: A method of welding in a groove (1) machined in a solid alloyed steel part, characterized in that bottom passes (2) are performed and then each wall (11, 13) of the groove (1) is faced with low alloy steel filler material, heat treatment is performed so as to eliminate the stresses in the zones (18, 19) of the part adjacent to the walls (11, 13) of the groove, and the empty space (20) between the two facing layers (15, 17) is filled with low alloy steel filler materials, said operation of facing the wall (11, 13) being performed by placing a carbon steel plate (4, 4', 2, 22') in the groove (1) at a certain distance from said wall (13, 11), by filling the space (12, 16) between the plate (4, 4', 22, 22') and the wall (11, 13) with layers (14, 14') of low alloy steel having a carbon content lying in the range 0.08% and 0.12%, and by getting rid of the steel plate (4, 4', 22, 22') and optionally a portion of the fill so as to leave only a layer (15, 17) on the wall (13, 11). The method can be used to get rid of a defect in a part while greatly reducing the risks of cracking.

Cathodic protection of steel in concrete

Abstract: Aspects generaux, systemes et etudes experimentales de la protection cathodique des aciers dans le beton

Effect of grain refinement on the endurance limit of plain carbon steels at various strength levels.

Abstract: The relationship between the endurance limit and ferrite grain size was investigated in a wide range of ferrite grain sizes using smooth specimens of low carbon steel, medium carbon steel and low alloy steel under rotating bending. It was found that the endurance limit of ferritic pearlitic steel clearly shows the Hall-Petch type relationship when the metallurgical parameters, such as chemical compositions and microstructural morphologies, are the same. The endurance limit can be determined by the additive effect of the strength level of matrix ferrite and the grain refinement. The effect of grain refinement on the endurance limit was constant irrespective of the strength level of matrix microstructure.

Monitoring Cathodically Protected Steel in Concrete Structures with Electrochemical Impedance Techniques

Abstract: The effectiveness of cathodic protection (CP) in mitigating corrosion on buried carbon steel structures is limited by the inability to (1) detect ongoing corrosion and (2) determine the level of CP in the presence of voltage (IR) drop in the environment. In this study, the feasibility was established for using electrochemical impedance spectroscopy (EIS) as a monitoring tool for detecting corrosion on cathodically protected carbon steel structures in soil and concrete.

Heat cycling of carbon steel wire

Abstract: 1. For refining the structure of carbon steel wire it is recommended to use HC. 2. The structure of steel after HC is granular pearlite of 1–2 points. Such a structure has a large margin of plasticity permitting cold drawing with a total deformation ɛt = 95–98%. 3. Heat cycling is an effective method of removing the cemenitite network in the structure of hypereutectoid steels. It helps improve the plastic properties of steel, and no graphitization is encountered.

High-Temperature Polarization Behavior of Carbon Steel in Alkaline Sulfide Solution

Abstract: The high-temperature (to 150 C) electrochemical polarization behavior of steel in highly alkaline sulfide solutions containing 2.5 molal (m) NaOH + 0.5 m Na2S is described. Anodic polariza...

Cold rolled steel sheets having improved spot weldability and method for producing the same

Abstract: An extra-low carbon cold rolled steel sheet useful for use in automobiles and the like having an improved spot weldability is obtained by combinedly adding Ti, Nb and B in predetermined amounts to the extra-low carbon steel so as to control the amount of fine Ti precipitate dispersed in steel to the specified reasonable range. Furthermore, the spot weldability is improved by controlling the production conditions of the extra-low carbon steel sheet to specified reasonable ranges.