High manganese Fe-Mn-Al-C alloy and its properties

• Autorzy: Mazancová E , Jonšta Z. , Mazanec K.
• Konferencja: Międzynarodowe Sympozjum: Metody oceny struktury oraz własności materiałów i wyrobów (XXIII ; 22-24.10.2008 ; Jarnołtówek, Polska)
• Języki publikacji: EN

Abstrakty

EN

Materials characterized as TRIPLEX having decreased density are constituted on the following chemical composition usually: Fe-26/30Mn-9/12Al-0.9/1.2C. Alloy microstructure is preferentially based on the FCC arrangement with annealing twins. Further, microstructure consists of low ferritic particle content 8-10% in maximum and of nano-size carbides regularly dispersed in the FCC matrix being coherent in maximum rate with that one [1]. Their quantity does not exceed 10 % level approximately. The reached carbide size corresponds to 20-30 nm. The k-carbides are nucleated after homogeneous annealing and followed aging at the temperature of about 500 °C - 600 °C. The existence of these particles is very important not only for specific form of deformation process being realized in the high manganese alloy of the TRIPLEX type. The strength level of this material is immediately connected with the solid solution strengthening forming the matrix basis. Besides this effect, it is useful to take into consideration process of its strengthening due to precipitated fine carbides (above mentioned nano-size k-carbides). In unite k-carbide cell aluminium atoms occupy its corners, manganese with iron are lying in all faces and carbon atom is situated in its body. It is well known the aluminium atomic radius reaches 0.147 nm, what represents greater dimension in comparison with iron atom having that one on the level of 0.126nm. In superposition manganese atom acts like aluminium one, even when its atomic radius only corresponds to 0.134 nm. It means with the higher aluminium and manganese weight fraction the TRIPLEX cell parameter is increased and matrix density is decreased, simultaneously. For example, in case of 12 % aluminium addition the density corresponds to level of 6.5g.cm-3 and represents a reduction of 1.4g.cm-3 in matrix density in confrontation with iron, what means the decrease density up to 10 % [1]. The preferential effect of material TRIPLEX is connected with its high absorption capacity, too. Double absorption capacity has been detected in comparison with the conventional deep drawing steels applied in automotive industry (crash test simulation). TRIPLEX matrix is strong stabilised thanks the high manganese level. Together with aluminium it is reason of a high level of the stacking fault energy (SFE) lying on the 80-110 mJm-2. Further, the stacking fault energy is responsible for the realized deformation process in TRIPLEX matrix being different e.g. to TWIP alloy. In any case none austenite decomposition into e-martensite is realized, as well [2]. In material TRIPLEX formation of uniformly arranged shear bands (SIP effect) is the sole deformation process being of very important influence. This process is accompanied by regular distribution of nano-size k-carbides being coherent to the FCC matrix. The k-carbides guide the shear bands formation as a matter of fact. Deformation process is accompanied by dislocation gliding. Obtained TRIPLEX strength level reaches l000MPa. Material shows an excellent formability and high resistance to dynamic loading (high absorption and achieved dynamic capacity). The presented high manganese alloy can be held for a perspective type for many applications in automotive industry. Further, this material finds a perspective application in cryogenic technique (transport and storage of liquid gases) and in rotating machine elements, too.

• Wydawca: Oficyna Wydawnicza Politechniki Opolskiej
• Czasopismo: Zeszyty Naukowe. Mechanika / Politechnika Opolska
• Rocznik: 2008
• Tom: z. 92
• Strony: 53--54
• Opis fizyczny: Bibliogr. 3 poz.

Twórcy

autor

Mazancová E

autor

Jonšta Z.

autor

Mazanec K.

• VŠB-TU Ostrava, Faculty of Metallurgy and Material Engineering, Ostrava, Czech Republic

Bibliografia

• [1] FROMMEYER G., BRŰX U.: Microstructures and mechanical properties of high-strength Fe-Mn-Al-C high-weight TRIPLEX steels. Steel Research Internat., 77, 2006, 9-10, 627-633.
• [2] HAMADA A.S., SOMANI M., KORJALAINEN CH.: High temperature flow stress and recrystallisation behaviour of high –Mn TWIP steels. ISIJ Internat., 47, 2007, 6, 907-912.
• [3] MAZANCOVÁ E.: New materials types for automotive industry-physical engineering properties of high strength and manganese alloyed materials and metallic hydrides alloys for hydrogen storage (in Czech). Monograph, VŠBTU Ostrava, 2007, 74 pages.