Characterization of the phase transformation in a nanostructured surface layer of 304 stainless steel induced by high-energy shot peening

• Published in: Physica. B, Condensed matter Condensed matter, 2003-06, Vol.334 (1), p.221-228
• Main Authors: Ni, Zhichun, Wang, Xiaowei, Wang, Jingyang, Wu, Erdong
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; High-energy shot peening (HESP); Magnetic resonances and relaxations in condensed matter, mössbauer effect; Martensitic transformations; Materials science; Mossbauer effect; other γ-ray spectroscopy; Mössbauer effect; other γ-ray spectroscopy; Nanostructured surface; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phase transformation; Physics
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/S0921-4526(03)00069-3

Conversion electron Mössbauer spectroscopy and X-ray diffraction analysis have been used to investigate the relationship between character of phase transformation and treatment time in surface nanocrystallized 304 stainless steel (SS) induced by high-energy shot peening (HESP). The results demonstrate that the amount of martensite phase increases remarkably with increasing HESP treatment time, till a maximum value (91%) is reached for 15 min treatment. Longer treatment duration only results in a slight decrease of the amount of martensite phase. Two types of martensite with different magnetic hyperfine fields are observed in the Mössbauer spectra. A theoretical model based on a random distribution of the non-iron atoms in 304 SS is presented to illustrate the relationship between the magnetic hyperfine field and the number of coordinating non-iron atoms. The calculation agrees well with the experimental results.