Unalloyed Steel Research Articles

Production-Related Surface and Subsurface Properties and Fatigue Life of Hybrid Roller Bearing Components

By combining different materials, for example, high-strength steel and unalloyed structural steel, hybrid components with specifically adapted properties to a certain application can be realized. The mechanical processing, required for production, influences the subsurface properties, which have a deep impact on the lifespan of solid components. However, the influence of machining-induced subsurface properties on the operating behavior of hybrid components with a material transition in axial direction has not been investigated. Therefore, friction-welded hybrid shafts were machined with different process parameters for hard-turning and subsequent deep rolling. After machining, subsurface properties such as residual stresses, microstructures, and hardness of the machined components were analyzed. Significant influencing parameters on surface and subsurface properties identified in analogy experiments are the cutting-edge microgeometry, S¯, and the feed, f, during turning. The deep-rolling overlap, u, hardly changes the residual stress depth profile, but it influences the surface roughness strongly. Experimental tests to determine fatigue life under combined rolling and rotating bending stress were carried out. Residual stresses of up to −1000 MPa, at a depth of 200 µm, increased the durability regarding rolling-contact fatigue by 22%, compared to the hard-turned samples. The material transition was not critical for failure.

The Use of Arc Welding Processes in the Additive Manufacturing of Metallic Products

The article presents examples of additive manufactured products obtained using MIG /MAG welding processes (13). The research-related tests revealed that it is possible to make products of unalloyed steels having the structure similar to castings subjected to heat treatment. Products made of maraging steel require homogenising (heat treatment). It is possible to produce bimetallic products, e.g. unalloyed steel-bronze.

A New Heat Treatment Cycle Design for High Wear Resistant in PM Steels

In this study, 1.5% by weight of natural graphite powders were added to Atomet 1001 pure iron powders and unalloyed high carbon powder metallurgy steel specimens were obtained. After the mixture was uniaxial pressed at room temper-ature and 700 Mpa pressing pressure, it was sintered in Ar protected atmosphere controlled oven at 1150 ° C for 20 minutes. The densities of the specimens before and after sintering were measured using precision scales and electronic calipers and presented graphically. After sintering, microstructure specimens containing primary cementite and typical dense perlite colonies were produced. The sintered specimens having primary cementite plus lamellar pearlitic structures were fully quenched from 950 °C temperature and then over-tempered at 705 °C temperature for 60 minutes to produce spherical-fine cementite particles in the ferritic matrix. After by this treatment, these specimens annealed at 735 °C temperature for 3 minutes were austempered at 300 °C salt bath for a period of 1 to 5 hours. After the heat treatment, dry sliding wear tests of specimens were carried out under 10N constant load and 500-1500m wear distance. At the end of the dry sliding wear test, the weight losses of the specimens were measured and it was determined that the dry sliding wear resistance increased with increasing austempering time after spheroidization annealing.

Effect of laser treatment of unalloyed steel on the efficiency of benzotriazole as a corrosion inhibitor in a neutral medium

Effect of laser treatment of unalloyed steel on the efficiency of benzotriazole as a corrosion inhibitor in a neutral medium

The role of molybdate‐containing inhibitors in cases of stress corrosion cracking in closed water circuits

AbstractIn this study, three cases of damage to heating circuits are presented, in which damage was caused by intergranular stress corrosion cracking in an unalloyed steel. The results are compared with literature data. From this, it can be concluded that stress corrosion cracking has been triggered in all three cases by the addition of an inhibitor containing molybdate. The development of this form of corrosion is only possible under critical conditions.

Heat Input Influence on the Fatigue Life of Welds from Steel S460MC

Fine-grained steels belong to the progressive materials, which are increasingly used in the production of welded structures subjected to both static and dynamic loads. These are unalloyed or microalloyed steels hardened mainly by the grain-boundary strengthening mechanism. Such steels require specific welding procedures, especially in terms of the heat input value. At present, there are studies of the welding influence on the change of thermomechanically processed steels’ mechanical properties, however mainly under static loading. The paper is therefore focused on the assessment of the welding effect under dynamic loading of welded joints. In the experimental part was determined the influence of five different heat input values on the change of weld fatigue life. As a result, there is both determination of five S-N curves for the double-sided fillet welds from the thermomechanically processed fine-grained steel S460MC and the quantification of the main influences reducing the fatigue life of the joint.

Properties of UNS 10276 Nickel Alloy and SA 516 GR 70 Steel Dissimilar Weldment

Abstract At moderate and high temperature applications, nickel-based superalloys are widely preferred as suitable candidate materials due to their high mechanical properties and corrosion/oxidation resistance, however, difficulties in mass production of these alloys and their cost cause the use of these alloys as a part of dissimilar weld joints with any structural material. In this study, a dissimilar weld joint between a nickel-based superalloy (UNS 10276) and unalloyed steel (SA 516 GR 70) was successfully performed by gas tungsten arc welding method by using ErNiCrMo-3 filler metal. Initially, the microstructural features of base materials, heat affected zone and weld metal were characterized and cellular, coarser cellular and epitaxial growth dendrites as matrix phases and several Mo-rich and Nb-rich precipitates embedded in the solidified structure were observed in weld metal. In heat affected zones and fusion lines of the dissimilar joints, some metallurgical phenomena like partially melted zone, solidification at grain boundary, migrated grain boundary and decarburization were also examined. All these microstructural features affected the mechanical properties.

Microstructure of Joints Made in High-Strength Steels Using the Robotic Laser Beam Welding Process

The paper presents the evaluation of weldability of unalloyed high strength heat-treated steels using of a laser beam welding robotic station. The key factors and properties affecting the usability of the aforesaid welding technology when welding the above-named steels were identified on the basis of the assessment of the microstructure and the measurements of hardness distribution in the related butt welded joints.

Influence of Heat Input and Welding Position on Geometrical Properties of GMAW Fillet Welds of Unalloyed Steel

This paper presents principal influences of heat input and welding position on geometrical properties of fillet welds for conventional and pulsed GMAW of unalloyed steel. We took into consideration geometrical properties such as fillet weld size, penetration, dilution and reinforcement. All presented influences are represented by fitting curves, based on simple linear regression of experimental data provided by visual and macro-section examination.

Analysis of the main trends in the development of the production of grinding balls in Russia and abroad

The article presents the results of the analytical review of the main trends in the grinding balls production in Russia and foreign countries. It is shown that grinding balls of domestic production have lower performance characteristics in relation to foreign counterparts, which is due to the technological features of their production, including the use of unalloyed steels with high hardenability and rejected billets of steels for other purposes (in most cases, rail steels), non-optimal technology of heat treatment. Based on the analysis, a list of promising areas for the development of domestic production of grinding balls that contribute to the competitiveness of this type of product in the domestic and foreign sales markets is determined. These areas include: increase in the share of rolled balls from alloy steels and cast balls from alloy cast irons, improvement of the technology of balls heat treatment and usage of new specialized steel grades for their production.

The Role of the Material of Active Screen During the Plasma Nitriding Process

Abstract In this research the effect of the active screen’s material was investigated. 42CrMo4 steel was plasma nitrided with unalloyed steel, titanium and nickel active screen at 490 and 510 °C for 4h in 75 % N2 + 25 % H2 gas mixture. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS) were used for the characterisation of the surface properties. Iron-nitride was not formed on the surface with nickel screen. The evaluation of examination results showed that most of the detected nitrogen was molecular (N2) in the formed layer.

Property Anomalies of Unalloyed Pre-Eutectoid Steel Melts at ~0.5% C as a Consequence of the Intermediate Fe42C Phase

In 1916, the Russian scientist D.K. Chernov depicted his vision of Fe–C diagram (immortalized at his tombstone in Yalta). A vertical line was drawn with his hand at 0.5% C on the diagram. In this paper, an attempt is made to substantiate the thesis that this vertical line is essential for explaining the properties of undoped pre-eutectoid melts. The anomalies in the properties of steel melts at ~0.5% C, established in different studies, are considered as additional signs of the presence of Fe42C intermediate phase, which manifests itself in well-known qualitative changes in structure and properties of solid state (martensite, ferrite, austenite, ferrite–cementite mixture).

Investigation of the ASPN process of low alloy steel by using Ni or Cr coated active screens

The mechanism of active screen plasma nitriding (ASPN) and the influence of the active screen's coating material on the surface properties of the nitrided layer was investigated on low alloyed steel samples, using chromium or nickel-coated active screens. ASPN experiments were performed at 510 °C, for 5 h in a 75% N2 + 25% H2 gas mixture using tempered 42CrMo4 type low alloy steel. The base material of the screens was unalloyed steel, but the screens were electroplated with chromium or nickel. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD), atomic force microscopy (AFM), and secondary neutral mass spectrometry (SNMS) were used for the characterization of surface properties of the samples and the screen. SNMS results show that the coating material of the active screen (chromium or nickel) was deposited on the surface of the samples in the form of compounds, with layer thicknesses between 160 and 200 nm (chromium) and 290–420 nm (nickel). Chemical analysis by X-ray photoelectron spectroscopy (XPS), performed at the interface of the steel sample and the deposited compounds reveals that iron-nitride was only formed in the case of samples that were treated with a Cr-coated active screen. Here the decomposition and oxidation of the unstable chromium-nitride provided the nitrogen atoms and the chemical drive for the formation of iron-nitride. In the case of the Ni-coated active screen, only molecular nitrogen was observed in the treated steel samples. The results prove that – contrary to widespread models on ASPN nitriding mechanisms – physically adsorbed nitrogen plays little role in the nitriding process of iron.

Synthesis of high-effective steel corrosion inhibitors in water-oil mixtures

It is a relevant and practically important task for environmental protection to devise effective means to protect metals against corrosion in aggressive media containing water, petroleum products, carbolic acids, and mineral salts. To stop corrosion, corrosion inhibitors are used that must be constantly improved and whose composition must be properly adjusted. The main drawback of the highly effective inhibitors based on alkyl imidazolines, a mixture of alkyl imidazolines with alkyl pyridinium and/or quaternary ammonium compounds soluble in a methanol medium, is their high prices at relatively significant consumption in the corrosive environment. This paper reports the synthesis of steel corrosion inhibitors in oil-containing aqueous environments that meet the stricter ecological and economic requirements. It has been shown that increasing the level of water mineralization improves the corrosive activity of aqueous environments relative to unalloyed steels. The presence of carbon dioxide, hydrogen sulfide, or carboxylic acids leads to the oxidation of water-oil mixtures resulting in the increased rate of steel corrosion. We have studied the effectiveness of the synthesized inhibitors based on oil and polyethylene polyamines containing imidazolines. At a temperature of 80 °C, the mixture that contained 200 cm3of a 3 % sodium chloride solution, 800 cm3of oil, and at the concentration of acetic acid of 0.5 and 3.0 g/dm3 at the inhibitor dose of 50 mg/dm3, has reached the degree of protection of steel against corrosion at the level of 90–92 %. Based on a full factorial experiment, the regression equation has been derived that makes it possible to easily enough calculate an optimal dose of the steel corrosion inhibitor in water-oil mixtures. It has been shown that the synthesized inhibitor shows prospects for protecting metals against corrosion both in the mineralized waters containing oil and in the presence of petroleum products containing water

Low cycle fatigue life prediction of the demining tiller tool

The paper presents strain-based fatigue assessment of the rotating demining tiller tool. In order to make a cost reduction, the idea was to replace initially applied high strength steel with unalloyed structural steels. To maintain the same or almost the same durability, the original geometry needed to be improved. The LCF theory was chosen as the verification tool. Transient nonlinear mechanical analysis and Low cycle fatigue (LCF) assessment was performed for tiller tool with high strength steel and unalloyed structural steels. The two step LCF assessment procedure has been proposed in order to improve tiller design. As the first step, a nonlinear transient FE analysis was done and as a result, elastic and plastic strains were found. In the second step the LCF assessment of the demining tool tiller was made according to von Mises strain amplitudes and Coffin-Manson model. Finally, it can be concluded that the proposed methodology for low cycle fatigue estimation yielded with the cost reduction, simpler production and maintained the desired tiller tool life.

EDM machining of die steel EN8 and testing of surface roughness with varying parameters

EN 8 belongs to BS 970 standard and is an unalloyed medium carbon steel used for where some better then normal mild steel which is having carbon ranges from 0.3 to 0.6%. The surface roughness of die while machining on EDM machine depends upon the working parameters of the machine. These working parameters will give fine, super fine and coarse roughness surface on the work piece. The main methodology consists of gauging of these parameters and analyzing the surface roughness. For this the experiment has conducted on EDM machine and the surface roughness will be measured and analyzed. Concept of single variable at a time approach at a time will be used to find out the effect of input parameters on the Surface Roughness. A series of experiments would be conducted to study the effects of various machining parameters of EDM. In each experiment, one input variable would be varied while keeping all other input parameter at fixed value. Studies will be undertaken to observe the effect of selected parameters viz; discharge current, T-ON pulse on time, T-OFF pulse off time, wire feed, servo voltage, MRR and Surface Roughness.

Влияние металлургических факторов на коррозионное растрескивание под напряжением различных сталей в агрессивной хлоридно-сульфидной среде

Проведен анализ влияния металлургических факторов на коррозионное растрескивание под напряжением сталей разного класса в агрессивном растворе NACE при 25oC. Получены зависимости напряжения перехода от активной коррозии к механизму водородного охрупчивания (критического напряжения) от величины предела текучести и коэффициента концентрации напряжений. Выявлена связь между критическим напряжением, условным пределом текучести и величиной перенапряжения. Сделан вывод о том, что потеря коррозионного сопротивления для нелегированных сталей с пределом текучести ниже 500 MPa обусловлена увеличением концентрации водорода в процессе деформации материала в коррозионной среде. Ключевые слова: коррозионное растрескивание под напряжением, водородное охрупчивание, предел текучести, коэффициент стойкости, сталь.

Selection of Wear Resistive Nano coating in En8 Steel

Where is the abrasive or gradual removal of materials at solid surfaces? It is caused due to the interaction between the sliding surface by mechanical action. The abrasive wears can be recognised as scratches or grooves. To enhance the wear resistance suitable nanocoating is applied on the material surface for better tribological properties such as hardness and toughness. Wear resistant nanocoating is used to reduce or eradicate wear to extend the lifetime of the EN8 steel. EN8 is unalloyed medium carbon steel with better mechanical properties than mild steel and also readily machinable in any condition. The nanocoating materials such as Al2O3, TiO2, SiC, ZrO2, WS2, Si3N4 etc., are used to reduce wear and to enhance hardness and toughness on mild steel through various nanocoating techniques. This paper deals with selection of suitable nanocoating material through AHP (Analytical hierarchal process) - a multi-criteria decision-making method.

Thermography in high cycle fatigue short‐term evaluation procedures applied to a medium carbon steel

AbstractThis paper focuses on the fatigue life calculation for an unalloyed medium carbon steel SAE1045 (German DIN‐standard: C45E), by applying an energy dissipation‐based approach quantified through thermographic measurements. The purpose of this approach is to establish an intrinsic dissipation model and to predict characteristics derived from the cyclic deformation behavior of stress‐controlled fatigue tests, eg, the fatigue limit and the S‐N data by using simplified (zero‐dimensional, 0D) thermodynamic equations. In order to investigate the possibilities for a rapid evaluation while simultaneously reducing the experimental effort, one load increase test (LIT) and two constant amplitude tests (CATs) were carried out. The S‐N data evaluated on such a basis is competitive to conventionally determined S‐N data as will be shown.

Effect of Boron Micro-alloying on Microstructure and Corrosion Behavior of Dual-Phase Steel

The present work aims to understand the effect of boron (B) as a micro-alloying element on the mechanical properties and corrosion behavior of a dual-phase steel that was prepared from boron-added steel via hot rolling. The ‘B’ micro-alloying increased the volume fraction of martensite from ~ 25 to 50% and improved the hardenability as compared to unalloyed DP steel subjected to similar rolling and heat treatment conditions. The yield strength, tensile strength and corrosion resistance of boron-added DP steel significantly improved from 405 to 690 MPa, 632 to 890 MPa and 0.125 to 0.110 mm/year, respectively, as compared to the unalloyed DP steel.