Formation mechanism of weak ferrite areas in Ni-containing powder metal steels and methods of strengthening them
Resource
Materials Science and Engineering: A, 527(21-22), 5421-5429
Journal
Materials Science and Engineering A
Pages
5421-5429
Date Issued
2010
Date
2010
Author(s)
Wu, M.W.
Hwang, K.S.
Abstract
The mechanical properties of Ni-containing powder metal steels are typically inferior to those of their wrought counterparts due to the presence of pores and soft Ni-rich/C-lean ferrite. To improve the mechanical properties, the distribution of alloying elements and the formation mechanism of the soft Ni-rich/C-lean areas were investigated. The results of diffusion couple experiments showed that a soft ferrite layer formed between martensite and pearlite phases. When Cr and Mo were added, the distribution of Ni and C improved and the ferrite disappeared. As a result, the tensile strength increased because the fracture path changed by passing through pearlite or along pearlite/martensite boundaries, instead of passing through ferrite. Based on the microstructure and diffusion couple results, schematics were presented to explain the formation mechanism of the weak Ni-rich/C-lean ferrite and its elimination by adding Cr and Mo. © 2010 Elsevier B.V.
Type
journal article
File(s)![Thumbnail Image]()
Loading...
Name
306.pdf
Size
23.45 KB
Format
Adobe PDF
Checksum
(MD5):2e8fa6416cac38e1f7d8fb9b73b0e69c