Mechanical behavior and martensitic transformation of an Fe–Mn–Si–Al–Nb alloy

✍ Scribed by B.X. Huang; X.D. Wang; Y.H. Rong; L. Wang; L. Jin

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 901 KB
• Volume: 438-440
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/j.msea.2006.02.150

✦ Synopsis

The microstructure features of an austenitic Fe-23Mn-2Si-2Al (mass%) alloy with addition of niobium (0.017 mass%) were investigated as a function of deformation temperature (20 to -75 • C). The observation of optical microscopy and transmission electron microscopy (TEM) indicated that a large number of twins induced by deformation above -60 • C result in relatively high total elongations of about 80% and the increase of the ultimate tensile strength from 660 to 750 MPa, which is called twinning-induced plasticity (TWIP). At temperatures below -60 • C, the stability of the austenite decreases and multiple martensitic transformations among ␥ fcc (austenite), hcp (hcp-martensite) and ␣ bcc (bcc-martensite) occur after TWIP effect, which were determined by both TEM and X-ray diffraction. With transformation-induced plasticity, total elongations reached 87% and ultimate tensile strength reached 810 MPa. The effect of Nb on TWIP/TRIP in the steel is discussed.