The effect of the impurities spaces on the quality of structural steel working at variable loads

Abstract

The quality of carbon steels working at variable loads mainly depend of microstructure, but also of impurities. The quantity and morphology of non-metallic inclusions and spaces between impurities are correlated with the content of admixtures in the alloy, while their phase composition and structure, in particular shape, dimensions and dispersion, are determined by the course of metallurgical processes. Non-metallic inclusions as impurities found in steel can affect its performance characteristics. Their impact depends not only on their quality, but also, among others, on their size and distribution in the steel volume. The literature mainly describes the results of tests on hard steels. The article discusses the results of a study investigating the effect of the number of large non-metallic inclusions (over 10 μm in size) on the fatigue strength of structural steel during rotary bending. The study was performed on 6 heats produced in an industrial plant. Fourteen heats were produced in 140 ton electric furnaces. All heats were desulfurized and refined with argon. The experimental variants were compared in view of the tempering the research steel. The fatigue strength of steel with an impurity spaces was determined during rotary bending: the results revealed that fatigue strength is determined by the impurity spaces and tempering temperature.

Effect of boronizing process of AISI 321 stainless steel surface on its corrosion resistance in acid environment (pH = 1)

“…This confirms the zonal presence of FeB and Fe 2 B precipitates, for which the stoichiometric boron content is 16.23% for FeB and 8.83% for Fe 2 B [31]. It should also be noted that due to the increased content of chromium and nickel in the tested steel, apart from the typical iron borides (FeB and Fe 2 B), the structure may also include precipitations: CrB, Ni 2 B and (Fe,M) 2 B, where M = Cr or Ni) [8,[32][33][34]. With the applied process parameters (at 900 °C for 6 hours), structural changes are observed up to a depth of approx.…”

“…Due to the wide range of applications as well as the wide range of possibilities of shaping the mechanical, tribological and other properties of austenitic stainless steels, their use is constantly growing [5]. The growing interest in this type of steels is also determined by the possibility of subjecting stainless steels to various methods of thermal, chemical or chemical-thermal treatment [6][7][8]. One of the methods of increasing the durability of structural elements that is applicable to austenitic steels is saturation of the surface with boron.…”

The Effect of Rare Earth Metals Alloying on the Internal Quality of Industrially Produced Heavy Steel Forgings

“…Only compliance with all system principles in the process will allow to obtain products with appropriate functional properties. Qualitative supervision is particularly difficult for such processes, as it is based not on 100% control, but on complex analyses of statistical production control, as in other processes in the field of materials science [1][2][3][4][5][6][7][8][9]. Large steel products produced by complex open-die forging processes are widely used in industries with high quality demands on structural and mechanical properties.…”

“…Only compliance with all system principles in the process will allow to obtain products with appropriate functional properties. Qualitative supervision is particularly difficult for such processes, as it is based not on 100% control, but on complex analyses of statistical production control, as in other processes in the field of materials science [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ].…”

Corrosion Fatigue Damages of Rebars under Loading in Time

“…The tendency for corrosion cracking to occur in steel reinforcement and its dependence on rebar diameter, mechanical properties and magnitude applied of stresses are investigated in the works [ 25 , 26 , 27 ].…”