Mechanical Properties Of Steel Research Articles

Rare Earths and the Mechanical Properties off Steel

While the western steel industry’s interest in rare-earth metals has waned since the 1970s, additions of this resource can nonetheless be used to improve the fatigue and creep properties of steel as well as depress temper embrittlement. With the largest rare-earth resources in the world, the Peoples’Republic of China has maintained a significant research commitment in this area, determining that several mechanical properties of steel may be enhanced aside from the traditional improvements in toughness characteristics. In desulfurization processing, for example, rare-earth injection favorably complements the calcium injection technology which is currently prevalent in the West. Further, rare earths react quite efficiently with the hydrogen in steels to lower the hydrogen diffusion coefficient.

Effect of shock-wave treatment on the mechanical properties of steels

Effect of shock-wave treatment on the mechanical properties of steels

Measurement of the yield strength of steel in the process of austenite decomposition

1. In the experimental study of the change of mechanical properties of steel in the process of decomposition of austenite, it is necessary to determine the stress-strain curves with simultaneous recording of the temperature and of the structural state (e.g., with the aid of a magnetometer) of the specimen, and also to determine independently the deformation of transformation plasticity. 2. In consequence of the narrowing of the temperature range of transformations under load, and also of the possibility of the specimen being heated upon release of heat of transformation, it is necessary to increase further the accuracy of maintaining and measuring the test temperature. 3. A theoretical analysis of hardening has to be carried out with a view to the interconnection between internal stresses and structural transformations of steel in finished products.

Effect of residual austenite on the mechanical properties of carburized steels

The effect of residual austenite on the mechanical properties of carburized steels was investigated by controlling residual austenite content during the specimen preparation stage and then conducting metallographic, layer-by-layer chemical and phase chemical, and x-ray analysis on carburized specimens of 25KhGT, 25KhGM, and 20KhN2M steels. Bending resistance, impact strength, and fatigue limit were also determined. Bench tests were also carried out on gear wheels. A directly proportional relationship was found between the carbon content in solid solution and residual austenite. An extreme relationship was established between the mechanical properties of the steels and residual austenite content in the surface layers with the attainment of maximum properties at content values of 35 to 50% for residual austenite.

Evaluation of the relationships between the indices of mechanical properties of materials

1. The “boot strap” method is an effective means of evaluation of the stability and existence of correlation relationships between the indices of mechanical properties of materials, especially in the case of limited statistical information. 2. Variations of the closest correlation relationships between the indices of mechanical properties of steels were established, including between the fatigue limit on one hand and the tensile, yield, and nominal bend strengths and parameter of the angle of slope of the fatigue curves on the other and also mutual relationships between the other indices with the most stable correlation coefficients.

Special features of fracture of carbon steel with a structure of laminar ferrite-carbide mixture

In [i, 2], we have published the results of our investigation concerned with the evaluation of the use of thermal processing in a magnetic field in order to harden carbon steel. It was established that under the action of a permanent magnetic field during isothermal annealing in the structure of carbon steel changes occur in the number of excessive phases, the degree of the dispersion of eutectoid increases as well as the fragmentation of the assembly of pearlite colonies. This causes a change in the mechanical properties of steel [2]. It can be assumed that the structural changes caused by the action of the magnetic field are bound to affect the fracture character of carbon steel.

Steel Mechanical Properties at Different Strain Rates

Dynamic test results reported by different investigators on structural steel, deformed reinforcing bars, and deformed wires subjected to monotonic tension are used for deriving empirical expressions for the ratios of static to dynamic values of the yield and ultimate stresses, yield and ultimate strains, and the strain at the end of the yield plateau. The principal variables in the expressions are the rate of straining and the steel static yield strength. These expressions are then used for developing dynamic constitutive models for monotonically loaded steel.

Effect of the strain rate on the mechanical properties and failure mode of high-strength steel

1. A change in the strain rate in the range from 6.3×10−3 to 1.9×103 sec−1 does not have a noticeable effect on the mechanical properties of steel. A further increase of\(\dot \varepsilon\) up to 1.9×104 sec−1 leads to an intensive increase in both the strength and plasticity properties. 2. With increase in the strain rate the effect of oxide NI on the failure process decreases, which should be considered during development of technological processes for obtaining steel. 3. The experimental results underscore the necessity to study the dynamic properties of construction materials in order to evaluate their serviceability under high rates of loading.

Influence of explosive loading on the micromechanisms of fallure of constructional steels

1. Explosive loading with p=5 and 10 GPa of specimens of St3sp and 20G2S steels leads in subsequent impact bend tests to complication of their fracture relief and to an increase in the degree of microlocal deformation, as the result of which the energy expenditure for the failure process may increase. The increase in relief is caused by complication of the trajectory of the crack, the development of which is a discrete process. The microcracks and then the main crack propagate in jump, the length of which is determined by the specific structure of the material. 2. The combination of explosive loading with subsequent heat treatment substantially increase the brittle fracture resistance of the investigated steels at low temperatures as the result of decreasing localization and more uniform occurrence of deformation and fracture. Explosive and heat treatment provides the optimum mechanical properties of steels [5, 6] and may be used when traditional methods of hardening and thermomechanical treatment are inapplicable.

Mechanical properties of carbon chromium-manganese steels with a structure of unstable austenite

1. The set of mechanical properties for steels with a structure of unstable austenite containing 0.6% C, O... 11% Cr, 8... 13% Mn is governed to a considerable degree by the level of structural stability in relation to formation of deformation martensite: formation of even a small amount of martensitic phases (several per cent) during extension or dynamic bend testing leads to embrittlement and a reduction in strength, ductility, and impact strength for the steel. 2. An increase in manganese content from 8 to 13% in steels of type 60Kh5 causes a reduction in Md temperature, an increase in deformation stability for austenite, and as a result of this an increase in the set of steel mechanical properties. An increase in chromium content to 6.5% in steels of type 60G10, which does not alter Md temperature, has little effect on the deformation stability of austenite and mechanical characteristics of steels, but a further increase in chromium content to 10.5% stabilizes austenite during plastic deformation. 3. An increase in test temperature for the steels studied to 150–200°C causes a reduction in the amount of martensitic phases formed during extension, as a result of which there is a sharp increase in ductility characteristics and the value of of with a reduction in the value of o0.2; with an increase in test temperature to 300°C the ductility properties of the steels decrease.

Influence of the mechanical characteristics of steels on their fatigue wear resistance

The influence of the mechanical properties of steels on their wear resistance under conditions of rolling friction has been studied. The purpose includes investigation of the basic rules of fatigue wear of D7KhFNSh and D5KhN2MFASh steels in rolling friction applicable to the rolling bearing balls of drill bits. For comparison, specimens of 55SM5FA steel were also studied. The results of a test of a ring and three balls of the same material are shown. The relationship of the wear resistance of steels to hardness, energy content, and the index shown which is a criterion of fatigue strength, is presented.

Effect of prior heat treatment on the properties of nitrided structural and tool steels

1. Prior heat treatment before nitriding affects the mechanical properties of steels; the highest strength is achieved after temper hardening, and the maximum ductility is achieved after TCT. 2. The thickness of the nitrided layer on each of the test steels (U8, 40Kh, and 3Kh2V8) after temper hardening and TCT is practically the same, and the layer thickness is greater after normalizing. 3. For components which under working conditions should have higher strength properties, it is recommended that temper hardening is carried out before nitriding, and for articles which should exhibit higher ductility properties and impact strength, thermal cycling treatment is recommended.

Mössbauer studies of medium-carbon, high-chromium martensitic steels

57Fe Mossbauer effect spectroscopy is employed to determine the relationship between the microstructure and the mechanical properties of martensitic steels with base composition Fe-10wt%Cr-0,26wt%C. The microstructure consists predominantly of two phases: martensite and austenite. The effect of low concentrations of both Mn and Ni on the structure and the mechanical properties of these steels is studied. The results indicate that Mn and Ni additions are equally effective in increasing the fraction of retained austenite. The austenite is an important phase since it is considered to be beneficial to the toughness of steel. However, we find that the impact toughness first decreases and then increases as a function of the fraction of austenite.

Chemo‐mechanical reliability of metallic materials in deep ocean environments — Part 1

The full development of marine technologies for the industrial exploitation of deep‐sea resources requires the availability of exhaustive engineering data on the degradation of constructional materials when immersed at great length in ocean environments. An overall review of behavioural figures from reliable sources allows to point out major weaknesses and uncertainties with candidate alloys and consequent demands for ameliorative and innovative investigation. Prominent objects of research can be envisaged, accordingly, in: (i) formulating low‐alloy steels whose surface is chemically convertible (by suitable pretreatments or free corrosion itself) so as to abate the rate of oxygen cathodic reduction i.e. the current density required for cathodic protection; (ii) singling out high‐strength steels whose resistance to corrosion‐fatigue and hydrogen embrittlement is in proportion to the strength level; (iii) developing cheaper alternatives to high‐molybdenum stainless alloys resistant to localised corrosion; (iii) combining (in optimal composites) the outstanding resistance of titanium to saltwater corrosion and the low‐cost good mechanical properties of steels.

High temperature degradation of structural materials in environments encountered in the petroleum and petrochemical industries: Some mechanistic observations

This paper reviews some of the important processes underlying high temperature degradation of structural materials used in the petroleum and petrochemical industries. Particular emphasis is palced in degradation processes involving the interaction of structural metals and alloys with environments containing sulfidizing, carburizing, and halogenizing species. In addition the effect of gaseous hydrogen environments at elevated temperatures and pressures on the mechanical properties of steels will be discussed. The mechanism of attack and the effect of alloying elements in these phenomena will be described and discussed.

Temperature Effect on Mechanical Properties of Steels in Elastic Impact

Temperature Effect on Mechanical Properties of Steels in Elastic Impact

Effect of residual austenite and content of hardening elements on the mechanical properties of transition class stainless steels

1. The mechanical properties of the transition class stainless steel 03K12N5KM in the quenched condition are determined by its phase composition and do not depend to any significant extent on its Co and Mo contents. 2. For the same steel in the aged condition, Co and Mo additions have an effect if the austenite content is less than 50%. If it is higher than 50%, then the mechanical properties of the steel are the same as in the quenched condition. 3. The maximum aging effect was observed for the steel with an austenite content of 10–20%, with the Co content increased from 8–10% to 12%, and the Mo content increased from 4–5% to 6%. The ulitmate tensile strength of such a steel is 30% higher and the impact toughness is 3 times lower. 4. The ductility and impact toughness of the steel studied are determined by its strength, which depends to an equal extent on the phase compostion and on the total concentration of alloying elements in the hardening phase. 5. To obtain maximum impact toughness, the Co and Mo concentrations in the steel have to be restricted to the minimum value which provides the necessary strength level.

Radiation damage and recovery of the mechanical properties of hardened Cr?Mo?V steel

1. In alloying of chrome-molybdenum steel with vanadium its radiation damage in the hardened condition is weakened in low-temperature (50–70°C) irradiation and strengthened with an irradiation temperature of about 300°C. 2. Restoration of the mechanical properties of steel irradiated in the hardened condition occurs during subsequent annealing at a higher temperature than in the same steel after hardening and high-temperature tempering, and with an increase in vanadium content the temperature of the start of restoration of the properties increases. 3. The experimental data obtained agree with the hypothesis of the influence of interstitial elements on the radiation damage of iron alloys and steel as a result of joining of vacancy-interstitial atom complexes or "molecular" type defects into vacancy-impurity accumulations.

熱ひずみ履歴を受けた溶接金属の機械的特性と溶接継手の変形解析への適用

Mechanical and metallurgical heterogeneity in wled joints, which is caused by thermal prestraining cycles, have an important effect upon their deformation and strength behaviors. If the mechanical properties of steels and weld metals subjected to thermal prestraining cycles can be estimated conveniently, it is easy to analyze the deformation behaviors of weld joints by use of numerical computation procedures.In this study three kinds of weld metals, which are formed at weld joints of a carbon steel (SM41B), an austenitic stainless steel (SUS304) and a martensitic cast steel (SCS5), were used for experiments. Their mechanical properties depended upon the thermal prestraining conditions, for example, peak temperature, retention time at constant temperature, multi-thermal prestraining cycles. The experimental results indicated that elastic limit, yield stress, strength coefficient and strain hardening exponent of materials sub-jected to thermal prestraining cycles could be expressed as a function of Vickers hardness.As an application, the material constants for elastic-plastic FEM analysis were determined from the Vickers hardness distribution of weld and butt weld joint were analyzed in terms of plastic zone extension from the view of mechanical heterogeneity.

Improving the mechanical properties of steel made by electroslag remelting and vacuum-arc remelting

Improving the mechanical properties of steel made by electroslag remelting and vacuum-arc remelting