Autor(es)

Sandim, Maria J. R. ; Nagamine, Luiz C. C. M. ; da Silva, Alisson Kwiatkowski ; Aota, Leonardo S. ; Han, Liuliu ; Cohen, Renato ; Sandim, Hugo R. Z. ; Gault, Baptiste ; Souza Filho, Isnaldi R.

• Tipo de documento: Artigo Científico
• Fonte: ACTA MATERIALIA; v. 272, p. 12-pg., 2024-04-30.

Resumo

An anomalous increase in magnetization was investigated in a cold-rolled high-Mn TRIP steel (16.8 wt% Mn) annealed at 350 degrees C for times varying from 5 to 120 min, before the start of austenite reversion (alpha' -> gamma). Besides in-situ and ex-situ magnetic measurements, the full characterization of this phenomenon was also performed with the aid of X-ray diffraction (XRD), Mo<spacing diaeresis>ssbauer spectroscopy, and microstructural characterization using electron backscatter diffraction (EBSD) and atom probe tomography (APT). Based on XRD measurements, the volume fraction of austenite and alpha'-martensite was estimated as a function of annealing time, as well as their lattice strain. Phase quantification confirmed the absence of newly-fresh alpha'-martensite in the material during annealing at 350 degrees C. Short annealing up to 15 min promoted the increase of Ms (saturation magnetization) due to stress relief in alpha'-martensite (Villari effect). Further annealing to 30 min promotes the decrease in Ms driven by short-range solute reorganization within the lattice. After 60 min annealing, the creation of long-range solutedepleted zones (i.e. confined zones highly enriched in Fe) causes a new increase in Ms. In comparison, for 120 min of annealing time, Ms tends to remain unaltered. These findings revealed that short- and long-range chemical fluctuations strongly affect the saturation magnetization of the steel and brought new insights on the use of magnetic probing as a tool for phase quantification in Mn-bearing steels. (AU)

• Processo FAPESP: 15/26409-8 - Estudo comparativo da estabilidade microestrutural e das propriedades magnéticas de dois aços Fe-Mn-C (1,5%Mne 17%Mn)
• Beneficiário: Isnaldi Rodrigues de Souza Filho
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 17/17170-7 - Caracterização microestrutural avançada de dois aços Fe-Mn-C (1,5 porc. Mn e 17 Mn porc. Mn) em diferentes condições metalúrgicas
• Beneficiário: Isnaldi Rodrigues de Souza Filho
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado