Characterization of carbonitrided layers formed on stainless steel by conversion electron Moessbauer spectrometry

Journal Article · Wed Nov 01 04:00:00 EST 1995 · Metallurgical Transactions, A

OSTI ID:131482

Kurosawa, Kazuyoshi; Li, H L; Ujihira, Yusuke; Nomura, Kiyoshi ^[1]; Kojima, Ryuji ^[2]

---

1. Univ. of Tokyo (Japan)
2. Nihon Parkerizing Co., Ltd., Kanagawa (Japan). Central Research Labs.

Austenitic stainless steel was carbonitrided by the tufftride process, and the hardened layers formed on the surface were investigated by conversion electron Moessbauer spectrometry (CEMS) and grazing angle X-ray diffractometry (GXRD). It was found that carbides such as M{sub 7}C{sub 3} ( M = Fe, Cr), chromium nitride (CrN), {var_epsilon}-nitride (M{sub 2}N, M = Fe, Cr), and {var_epsilon}-carbonitride {l_brace}M{sub 2+x}(C,N), M = Fe, Ni{r_brace} were precipitated on the outermost surface at the initial stages of carbonitriding. By the increase of treatment time up to 20 and 30 minutes, {var_epsilon}M{sub 2+x}(C,N) became a main component, while M{sub 7}C{sub 3} and CrN disappeared in the outermost surface. After 60 minutes, M{sub 7}C{sub 3} and CrN were observed again, and the {gamma}{prime} nitride, the oxide of iron and chromium (FeCr{sub 2}O{sub 4}), was formed on the outermost surface for the first time. Cross-sectional micrographs of surface layers using a scanning electron microscope (SEM) after etching the hardened layers with Marble reagent revealed the presence of black and white layers. The former layer mainly consisted of {var_epsilon}M{sub 2+x}(C,N), {var_epsilon}M{sub 2}N, CrN, and M{sub 7}C{sub 3}, and the latter layer did not contain nitrogen, although carbon was detected in both layers. The Vickers hardnesses of the black and white layers were HmV(0.1) 1,000 to 1,200 and HmV(0.1) 500 to 600, respectively. It was said that both layers were harder compared with HmV(0.1) 200 of bulk. The white layer was far superior to the black one in ;the corrosion resistance proved by anodic polarization curve measurements in 5 vol pct H{sub 2}SO{sub 4} solution. The white layer formed on carbonitrided stainless steel beneath the black layer has possibilities as an excellent corrosion and wear resistive layer.

• OSTI ID: 131482
• Journal Information: Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 11 Vol. 26; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
36 MATERIALS SCIENCE
AUSTENITIC STEELS
AUTOMOBILES
CARBIDES
CARBONITRIDES
CORROSION RESISTANCE
HARDNESS
MATERIALS
MICROSTRUCTURE
PRECIPITATION
SCANNING ELECTRON MICROSCOPY
SURFACE HARDENING
WEAR
X-RAY DIFFRACTION