Papers by Keyword: Fe-Mn Alloys

Abstract: A comparative study of the structure and properties of two biodegradable Fe – 27Mn and Fe – 27Mn – C alloys for biomedical use after equal channel angular pressing (ECAP) has been carried out. It is noted that addition of carbon in the alloy leads to a change in the mechanism of plastic deformation from the formation of martensite to deformation twinning in austenite. ECAP improves the strength characteristics of the alloys under study and the corrosion rate by refining the structure and increasing the dislocation density. The presence of a partially twinned structure in the Fe – 27Mn – C alloy results in a lower corrosion rate despite a stronger refinement of the alloy structure after ECAP.

Abstract: In the present study, the microstructure, martensitic transformation and damping characteristics of Fe-17Mn-xNb (x = 0, 0.5, 1, 2, 4 wt. %) alloys were investigated. Nb addition leads to the variation in both the volume fraction and the size of ε martensite, in addition, the formation of Fe₂(Nb, Mn) precipitates. The martensitic transformation exhibits a tiny dependence on the content of Nb. The addition of Nb helps to enhance the damping capacity of Fe-17Mn. The maximum value of tan δ = 0.054 is achieved in Fe-17Mn-1Nb alloy, which is increased by 42% over Fe-17Mn. The damping mechanism caused by adding Nb is discussed in terms of the volume fraction and the size of ε martensite. Besides, the role of Fe₂(Nb, Mn) is also taken into account.

Abstract: Microstructures and damping properties have been investigated in Fe-23%Mn-(0~2)%Si and Fe-23%Mn-(0~2)%Co alloys, based on experimental results from metallography, X-ray diffractometry and vibration test in a flexural mode. The amount and number density of ε martensite are increased with an increase in Co content, resulting in the improvement of damping capacity. For the same ε martensite content, the higher the Co content, the greater the damping capacity. On the contrary, an addition of Si affects to decrease the amount and number density of ε martensite, giving rise to a decay of damping capacity. The decreased ε martensite content by the addition of Si would be attributed to an increase in critical driving force for the γ→ε martensitic transformation by solution hardening effect.

Abstract: Effect of Cr addition on damping capacity, mechanical property, and corrosion resistance of Fe-18%Mn martensitic alloy has been studied. Martensite start temperature (Ms) of the alloy decreases linearly from 150 to 25
with increasing Cr content up to 15%. The damping capacity decreases gradually from 27 to 23% in SDC with increasing Cr content from zero to 10%, and decreases rapidly with further Cr content. The tensile strength of the alloy maintains a level of 60
/ regardless of Cr content with an elongation of 20 to 25%. Immersion test in 5% NaCl solution leads to the result that the corrosion resistance of the alloy becomes excellent above 10% Cr. From the above results, it is concluded that the optimum Cr content to improve the mechanical property and corrosion resistance of the alloy with a lesser decrease in damping capacity is about 10%.

Abstract: We reports the damping properties of an Fe-23%Mn alloy with various amounts of thermal or deformation-induced ε martensite. By controlling cooling temperatures and cold rolling degrees, the volume fractions of thermal and deformation-induced ε martensites are changed from 33 to 50% and from 33 to 75%, respectively. The damping capacity of the Fe-23%Mn alloy increases with an increase in thermal ε martensite content, whereas the damping capacity associated with deformation-induced ε martensite shows a peak value at 57% of ε martensite. Transmission electron micrographs on deformed samples reveal that the decay of damping over 57% of deformation-induced ε martensite is caused by an introduction of perfect dislocations, which play a role in suppressing the movement of damping sources. For the same amount of ε martensite, deformation-induced ε martensite exhibits higher level of damping capacity than thermal ε martensite. This may well be owing to relatively greater length of γ/ε interfaces in response to higher number density of ε martensite plates.