Effect of annealing on point defect population in cold-drawn pearlitic steel wires

Nanocrystalline steel obtained by mechanical alloying of iron and graphite subsequently compacted by high-pressure torsion

“…3), as would be expected when such an amount of carbon was dissolved on interstitials in bcc iron without the presence of vacancies; obviously, the lattice dilatation due to carbon is exactly compensated by the lattice contraction due to vacancies, and the measured lattice constant is that of pure iron. The DSC peak at 577 K of the pearlitic steel was interpreted as the heat release during decomposition of vacancy clusters consisting of about 10 vacancies decorated with carbon, an interpretation that was substantiated by PAS results [53]. Here, too, it can be assumed that vacancy clusters are formed during MA and/or HPT, and decompose at temperatures between 500 and 600 K, however in amounts smaller than in pearlitic steel wires, a proposition that is substantiated by the fact that the heat release in case of pearlitic steel wires was 250 J mol À1 , and in case of the compacted powders merely 50 J mol À1 .…”

“…7, they can be compared with results of DSC performed on cold drawn pearlitic steel wires [53]. These results exhibit a peak at 416 K and one at 577 K, quite near the peaks at 427 K and 639 K registered in case of the compacts this work is dealing with.…”

“…It seems reasonable to assume that HPT does not lead to a reduction of the carbon content inside the grains. In case of the pearlitic steel wires, the heat release of the 416 K peak was DH % 130 J mol À1 , and a vacancy density on the order of 10 À4 was concluded [53]. In case of the compacted powders, DH % 360 J mol À1 , suggesting a higher vacancy density, most probably also present as V 1 C 2 and V 2 C 4 agglomerates.…”

Microstructure and mechanical properties of medium-carbon steel bonded on low-carbon steel by explosive welding

“…The missing lattice expansion is not a contradiction: Först and co-workers predict that excess carbon in -Fe causes greatly enhanced vacancy concentration, present mainly as V 1 C 2 and V 2 C 4 agglomerates when the vacancy concentration is larger than 10 6 [38]. It has been shown that in case of cold drawn pearlitic steel wires as well as in case of ball-milled Fe-C alloys that were subsequently subjected to high-pressure torsion, ferrite was supersaturated with carbon up to 0.1 -0.2 wt.% and showed no deviation of the ferrite peak positions in XRD [39,40]. In both cases, the presence of superabundant vacancies was shown by differential scanning calorimetry, where an exothermic peak at about 430 K documented the annihilation of vacancies.…”

Caracterização Da Microestrutura E Comportamento Mecânico De Fios De Aço Perlítico Trefilados

“…A elevada resistência associada com níveis aceitáveis de ductilidade apresentada por estes aços tem sido por muitos anos, tópico de considerável pesquisa cientifica [1]. A estrutura predominantemente perlítica é responsável por esta combinação de propriedades pois a microestrutura escalonada incorpora o constituinte dúctil no constituinte com elevada dureza, ou seja a morfologia do composto lamelar ferrita-cementita.…”