摘要:

Direct alloying of steel with tungsten concentrate in an Ar‐stirred ladle was investigated in a laboratory scale. Kinetics of WO3reduction in slag was analyzed according to the experimental results. Reduction of (WO3) by [Si] is the main reaction during direct alloying. The intensity of Ar stirring and [Si]content have great influence on the reduction rate of (WO3). Reduction of (WO3) is a second order reaction.

ISSN:0003-8962    

DOI:10.1002/srin.199400932

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

An automatic facility for rapid determination of the activities of FeO in metallurgical slags has been developed, by employing an electrochemical technique incorporating stabilized zirconia as solid electrolyte, a mixture of Mo + MoO2as reference electrode and an Mo rod as an electrical contact. With this equipment, one datum is obtainable within 5 minutes. In the present article, discussions were held on potential applications of this system to steelmaking process control. A particular emphasis is given to the control of FeO levels in slags used for secondary steelmaking and chromium levels in stainless steelmaking slags.

ISSN:0003-8962    

DOI:10.1002/srin.199400933

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

The objective of the paper is the assessment of the predictive ability of the thermomechanical‐microstructural model for the closed‐die forging process. The model combines the rigid‐plastic flow formulation with the finite element solution of the Fourier equation with the closed‐form equations describing processes of recrystallization and grain growth. Experimental validation of the mechanical and thermal components of the model is presented in earlier publications; present work focuses on the microstructural part. Experiment includes closed‐die forging of the carbon‐manganese steel samples and the measurements of the grain size on the cross‐sections of the forgings after the deformation. Spherical samples, which involve significant inhomogeneity of the strain and the temperature fields, have been chosen for a presentation of the results.

ISSN:0003-8962    

DOI:10.1002/srin.199400934

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

First the material model for elastic‐inelastic behaviour is explained against the background of cold straightening of plane workpieces. The change in geometry of the yield surface in the case of very small cyclic deformations and the influence of isotropic and kinematical work hardening are taken into account. Then case studies on numerical shakedown simulations and on the limits of cold straightening of plane workpieces follow using two material models. Finally the attainable permanent curvature is shown as a function of load and of the number of cycles. Residual stresses and the spring‐back resilience involved are taken into account.

ISSN:0003-8962    

DOI:10.1002/srin.199400935

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

In the study of the phase transformation of steel several methods can be used to obtain information about the behaviour of steel during heating and cooling. In this research several conventional methods, e.g. dilatometry, were studied together with an in‐situ thermal analysis method (ISTA). This method, which can be applied to any cooling curve, enables us to draw conclusions as to the transformation behaviour of the steel. Using a continuous annealing simulator (Casim) a range of cooling rates can be investigated with the resulting mechanical properties.It will be demonstrated that ISTA can be performed on the results of a variety of experimental techniques and therefore under very different experimental conditions. It is possible to investigate transformation behaviour and mechanical properties on a single test piece. Using the pressurized air cooling of the Casim proves to be a good compromise between the possibilities of determining the mechanical properties and flexibility in cooling conditions of the specimens.

ISSN:0003-8962    

DOI:10.1002/srin.199400936

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Hydrogen induced cracking was investigated for hot‐rolled titanium steels. Aim of the present work was to observe the influence of titanium content and grain size on the cracking behaviour. Three titanium steels (0.12‐0.30 % Ti; O.0057‐0.0480 % C) and one non‐titanium steel (0.0056 % C) were used for the investigation. Various grain sizes were generated by heat treatment at 950, 1050 and 1150 °C; furnace cooling was applied. The specimens were electrolytically charged with hydrogen at various current densities. It was found that cracks are generated at low charging current densities for the investigated steels. The titanium steels showed better performance than the non‐titanium steel. It was shown that the charging current density does not correspond to the hydrogen concentration in a steel; the hydrogen concentration in steel B was 3.8 ppm at 1 mA/cm2, in steel D it was found to be 15.5 ppm at 0.5 mA/cm2. The total hydrogen concentration was found to be influenced by content of precipitates and grain size. It was shown that the percentage of cracked grain boundary area increases with increasing grain size. This increase is linear for the non‐titanium steel whilst for the titanium steels a plateau was observed at a grain size diameter of 50 μm.

ISSN:0003-8962    

DOI:10.1002/srin.199400937

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

A creep function using only three fitting parameters is presented hereafter. The function is derived from a more general physical ‐ phe‐nomenoiogical model representing metallic materials creep behaviour and describes all three stages of creep. The dependence of the fitting parameters upon the temperature are investigated and simple analytical relations are provided for that purpose. Those relations already incorporate the effect of stress. At the outcome, ten material constants are derived which are neither dependent on the stress nor on the temperature. On the basis of the derived constitutive relations a prediction is carried out for creep strain of three metallic materials and particularly steels, at different temperatures and under constant stress. The derived curves agree with the experiments, not only the ones carried out in the laboratory but also the ones taken from literature.

ISSN:0003-8962    

DOI:10.1002/srin.199400938

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

The effect of Na2SO4coating on the corrosion behaviour of 5 steel alloys as well as two commercial alloys ‐ type 304 stainless steel and Inconel 690 ‐ were tested in air at 900 °C under atmospheric pressure. Corroded samples were analysed by XRD, SEM and EDX. A newly developed alloy (No. 5) having the composition Fe‐10.4Cr‐15.43Ni‐5.52Mn‐5.52AI‐1.5Si showed almost comparable corrosion resistance with Inconel 690. Stainless steel 304 failed catastrophically. Other newly developed alloys (no. 1‐4) showed intermediate resistance. The results have been interpreted in the light of the nature of scales formed and on the premise that Na2SO4decomposes to give S2‐ions which delay the formation of an internal protective film.

ISSN:0003-8962    

DOI:10.1002/srin.199400939

出版商:Wiley    

年代:2016

数据来源: WILEY