Purpose: The aim of the paper is a monographic presentation, based on investigations connected with the elaboration of new kinds of microalloy steels and a technique of heat and thermo-mechanical treatment in the production of a selected group of metallurgical products. Design/methodology/approach: The influence of the chemical composition and metallurgical purity on the homogenisation of austenite was analysed, as well as thermally activated processes and phase transformations in the course of deformation and controlled cooling conditions, concerning micradditives Nb, V, Ti, B and metallurgical products. Findings: The chemical composition of the obtained constructional steels with microadditives was quoted, as well as the technological conditions of forging and rolled products required for industrial purposes. Research limitations/implications: The results of investigations concerning the structure and mechanical properties have been presented, as well as the resistance to fracture, mainly of thick plates and hand-forged and drop-forged products and also elements of sheet structures for the automotive industry, made of AHSS steels. Practical implications: The results of the author’s own investigations concerning microalloy steels indicate the actual possibility of their application in practice in many steelworks, particularly in plants producing semi products and final metallurgical products, among others in hot rolling plants and forging shops, first of all in machine building and automotive industry. Originality/value: The application of modern metallurgical technologies and metalforming has been suggested for selected metallurgical products of microalloy steels of the type HSLA with a ferrite-bainite, bainite or tempered martensite structure and also of HSS steels and UHSS steel with a wide range of mechanical properties and technological formability, which is essential in the case of products of the automotive industry.
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Purpose: The aim of the investigations is to elaborate the optimum conditions of anodic dissolutions from highstrength microalloyed Weldox steels in order to obtain indispensable quantities of electrolytic extractions and to identify them by X-ray phase analysis. Design/methodology/approach: Anodic dissolution of steel was carried out according to the potentiostatic method. In the X-ray qualitative analysis the comparative method was applied. The corrosion resistance of steels was determined by means of the first method of Stern - Tafel. Findings: The activity of anodic dissolution of the investigated steel was determined in various solutions of electrolytes with different pH and a different complexive affect versus iron. Practical implications: It has been found that the application of an optimal reagent for the anodic dissolution of Weldox Steel and of the chronopotentriometric method permit to get the required mass of electrolytic extraction for the qualitative X-ray phase analysis. Electrochemical investigations permitted also to assess preliminarily the corrosion resistance of the investigated steels. Originality/value: It has been found that there exists a distinct relation between the mass of electrolytic extractions and the kind of the dissolved precipitation and the value of the electrochemical potential of the anodic dissolution of steel, which affects essentially the result of the X-ray phase analysis. Besides, a high corrosion resistance of the investigated steels to the destructive effect of a saline environment and a low resistance to an acid environment have been detected.
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