Light-weight steels based on iron-aluminium - influence of micro alloying elements (B, Ti, Nb) on microstructures, textures and mechanical properties

Abstract

The influence of the micro alloying elements B, Ti and Nb on the recrystallization texture and mechanical properties of iron aluminium light‐weight steels, particularly with reference to their improved deep drawing properties was investigated. Depending on the combination of the alloying elements the microstructures of the investigated micro alloyed Fe‐6Al steels are influenced by grain refinement. Likewise, variable combinations of micro alloying elements differently affect the texture. Generally, the mechanical properties are improved. However, small amounts of B, Ti and Nb cause superior deep drawing and stretch forming properties of these iron aluminium light‐weight steels The microstructures of various micro alloyed cold rolled Fe‐6Al steel sheets were evaluated by optical microscopy, scanning electron microscopy (SEM) inclusively EDAX and X‐ray diffraction. Texture measurements were performed using a goniometer with a closed Eulerian cradle and analysed by ODF calculations. Tensile tests were carried out at room temperature and 200 °C, respectively. The deep drawing behaviour was determined by performing cupping tests and digitalised strain analysis.

Effect of C content on the microstructure and tensile properties of lightweight ferritic Fe-8Al-5Mn-0.1Nb alloy

“…It has been known that the density of steels can be reduced by the addition of Al and therefore there is a growing interest in developing Al containing steels, so-called lightweight or low density steels [1][2][3]. Depending on the type of major constituent phase, these lightweight steels can be classified into several types; ferritic [1,[4][5][6][7][8][9][10][11][12][13], austenitic [14,15] and ferrite-austenite duplex types [9,16,17]. Having lower mechanical properties compared to those of austenitic or duplex steels [2], ferritic lightweight steels have received less attention than other types.…”

“…Having lower mechanical properties compared to those of austenitic or duplex steels [2], ferritic lightweight steels have received less attention than other types. Although there has been no systematic study on the effect of grain size on the mechanical properties of ferritic lightweight steels, analyses of their microstructures available in literature show that their grain sizes are rather coarse (over 40 µm) in final products [5][6][7][8][9][10][11][12]. Unlike the austenitic and duplex lightweight steels, mechanical properties, particularly ductility, of ferritic lightweight steels would be strongly dependent on the grain size due to their bcc structure.…”

Overview of Lightweight Ferrous Materials: Strategies and Promises

“…It has also been shown that C content in Al-containing ferritic steels should be minimized to avoid the possible formation of ordered carbides, Fe 4Ày Al y C x (0.8 £ y £ 1.2; 0 £ x £ 1), 41 which are detrimental to sheet formability. This has led to the development of high Al-containing low-density IF steels 20 with the addition of a stoichiometric amount of stabilizing elements such as Ti, similar to traditional IF steels.…”

Property and Cost Optimisation of Novel UHS Stainless Steels via a Genetic Alloy Design Approach

“…However, such substitutions are not straightforward if other effects and interactions among alloying elements are to be taken into account. Therefore, incessant efforts have been taken throughout the development of steels, both by industries and academies, to modify steel with leaner chemistry [9][10][11][12][13] and/or more economical process routes. 14,15) Nevertheless, competing and/or conflicting alloying effects on alloy cost versus alloy properties, make the empirical alloy design approach even more inefficient and hence a system optimization of the performance/price ratio in alloy design become an even more attractive target.…”