Steel Subject

Figure 7.8. Material hardness of Hadfield steel subject to shock compression of various peak pressures and pulse durations.

Because C-curves are determined by quench-hold-quench sequences they can, strictly speaking, only be used to predict the micro structures that would be produced in a steel subjected to a quench-hold-quench heat treatment. But the curves do give a pretty good indication of the structures to expect in a steel that has been cooled eontinuously. For really accurate predictions, however, eontinuous eooling diagrams are available (see the literature of the major steel manufacturers). 

The presence of small quantities of S in steels has little effect on the initial scaling rates in air, but may be detrimental to long-term scale adhesion. Sulphur has, however, been shown to be detrimental to breakaway oxidation in CO/CO2 environments. However, sulphur has been shown to reduce the total uptake of carbon in the steel under CO/C02 and reduce the scale thickening rate. In this context, free-cutting steels were found to oxidise at a significantly lower rate, as did steels subjected to pretreatment in H2S. 

A relative decrease in Tafel slope has been observed with steel subjected to thermal treatments leading to different microstructures [274]. In this case an effect can indeed be expected because of the possible formation of different phases or different proportions (martensite vs ferrite) of phases (Fig. 10). An effect of the size of grains has been observed on the Tafel slope. 

Figure 1 Surface finish versus pitting potential for 316 stainless steel subject to various surface treatments. (From G. E. Coates. Materials Perf., Aug. 1990, p. 61.)...

Typical acoustic emission spectra of a steel subjected to spheriodization treatment in underannealed (80% pearlite, 20% spheroids) and optimally annealed (100% spheroids) are shown in Figure 2.15. The emission spectra show distinct features of the effect of heat treatment. Similar differences are seen in other situations such as crack growth in samples. 

Figure 2.15 Acoustic emission spectra of steel subjected to spheroidization heat treatment (a) 80% pearlite, 20% spheroids (underannealed (b) optimally annealed, 100% spheroids. (Reprinted with permission from ASM International. All rights reserved www.asminternational.org)...

Reddish brown rust (ferric hydroxide) is usually evident on the surface of iron or steel subject to the presence of oxygen in the atmosphere and in contact with water. It is produced by the following chemical reaction ... 

The tip and substrate current spikes in Figure 46 are generally well correlated (particularly at times greater than 8 s), suggesting that the breakdown of the passive layer (substrate current) involves the release of Fe2+ from the iron surface, which was detected by reduction to Fe(0) at the tip UME. Evidence for the presence of Fe(0) at the tip came from the visual observation of a reddish-brown film at the electrode surface after such measurements and cyclic voltammograms (CVs) recorded with the tip positioned close to the iron surface, before and after a corrosion experiment. Prior to corrosion measurements, the tip CV displayed features consistent only with the reduction of TCA, while after corrosion the CV also showed a cathodic wave, possibly due to the reduction of Fe2+ to Fe and a corresponding anodic stripping peak. The latter occurred at the same potential as the anodic dissolution of iron, and was thus attributed to the reoxidation of Fe(0). Denuault and Tan (68,69) used a similar approach to identify the dissolution products for mild steel subjected to an acidic corrosive environment. In contrast to the work of Wipf and Still, the tip electrode was used only as a detector and not as an initiator of the corrosion process. CVs recorded with the tip placed close to the substrate detected the presence of Fe2+ and H2. 

S.J. Pawel, The Sensitization Behavior of Cast Stainless Steels Subjected to Weld Repair, master s thesis, University of Tennessee Library, Knoxville, TN, 1983... 

P. Smith, S. Roy, D. Swailes, S. Maxwell, D. Page, J. Lawson. A model for the corrosion of steel subjected to synthetic produced water containing sulfate, chloride and hydrogen sulfide. Chemical Engineering Science, Vol. 66, No. 23, pp. 5775-5790, 2011. 

Large plastic deformation can be identified by the accumulation of slips at the macroscopic scale as well as at the atomic scale. During tensile deformation, metal blocks slip on slip planes and rotate, as schematically illustrated in Fig. 1. Increasing plastic deformation results in numerous cross slips. Such slips can be observed as Luders bands in annealed low-carbon steel subjected to tensile deformation. 

Shot-peening is used to alter the surface condition of stainless steel subjected to fatigue conditions. Essentially the initial imposition of extra surface stresses causes local deformation that re-adjusts the stress state within the region. This process relaxes high local stresses. The subsequent creation of a thin layer of compacted steel introduces a residual compressive surface stress. Under usage conditions, externally applied tensile stresses are offset by this inherent compressive stress, as a... 

Figure 8.15. S-N curve for steels subjected to cyclic stress.

Chromium (used as a wear-resistant plating for steels) Subject to pitting in chloride environments Chromium, being cathodic to steel, does not corrode itself, but promotes rusting of steel where pits occur in the coating... 

The reaction mechanisms by which the alloy elements influence the rate of corrosion of weathering steel are not precisely known. While the presence of alloy elements improves the corrosion resistance of a carbon steel subjected to humidity cycles, during a simple immersion test weathering steel and carbon steel yield... 

Figure 11.18 Reduction in area as a function of the strain rate for type AISI 4340 steel subjected to cathodic polarization in seawater leading to hydrogen embrittlement (o) polarization of 0.76 V ( jpolarization of 0.61 V. The grey zone shows values typically found in air.

Figure 11.35 Time to failure for different austenitic stainless steels subjected to constant-load stress corrosion cracking testing in boiling magnesium chloride solution [15].

It was soon found that among the variables affecting corrosion rates were certain heat treatments that made not only the ferritic stainless steels subject to intergranular attack, but also the austenitic, 18Cr-8Ni alloys. From this simulated service test in boiling 65 % nitric acid, there evolved Practice C of ASTM A 262. Its large-scale use by one... 

In a second example, CF is promoted by increased impurity-sulfur in ferritic steels subjected to low-frequency loading in pressurized pure water at 288°C (Fig. 15) [22,23], MnS inclusions, which intersect crack flank surfaces, dissolve to enrich the occluded crack solution in sulfide. These anions promote crack advance by increasing the anodic charge that is passed per film rupture event, or perhaps by the HEE mechanism. This effect of steel sulfur content is severe for a stagnant environment within the autoclave, and is eliminated by turbulent solution flow which reduces sulfide buildup within the crack [66],... 

Samples of iron Fe and S235JR steel subjected to corrosion test not only differed in structure and chemical composition, but also the morphology and surface topography (Fig. 11), which had also influenced the course of corrosion processes. Both the iron Fe and S235JR steel were submitted to imeven general corrosion (Fig. 16). Material pickling on the grains boundaries is clearly visible in the case of electrochemically produced iron. 

Figure 10.3 shows a diagram demonstrating the change of copper concentration in the surface layer of steel 45, subjected to EEA and following EBR From the analysis of the results it follows that in the surface layer of thickness 4-5 pm (thickness layer of steel, subjected to analysis) the average concentration of copper is reduced from 14 wt. % at a energy density of electron beam Es = 15 J/cm up to 5.6 wt. % when Es = 30 J/cm. It... 

As it is shown above, the processing of the alloying surface by the electron beam with energy density of the electron beam 20 J/cm and above is accompanied by extensive melting of the surface layer of steel. After 5... 15 pulses of the electron beam effect the islands and the nodules of copper, presenting on the surface of the steel, subjected to EEA are not detected by methods of scaiming microscopy. The surface of the samples is fully smoothed. After 25 and 50 pulses of the electron beam effect on the surface one can see a large number of craters. 

Construction codes generally provide maximum allowable temperatures of materials. As a guideline, the allowable temperature for reinforcing bars and structural steel subjected to short term (less than six hours) fires is 500°C [22]. This value may be used unless a different value is provided by codes or otherwise justified. 

The EAS of the melts recorded during the anodic dissolution of samples of AISI 316L steel subjected to a prior annealing are given in Figure 6.5.7. 

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