碩士 / 國立海洋大學 / 材料工程研究所 / 84 / The atmospheric-corrosion behavior of pressurized-vessel
steel (A516) and SUS 304 stainless steel was studied over the
temperature range of 200 - 400oC in a simulated marine
environment. The effect of NaCl surface-coating (2 mg/cm2) on
corrosion kinetics of both steels was also addressed, and the
kineticsresults were compared with those without coating. The
nature of the A516 steel is a banded structure, while SUS 304
shows a fiber structure. The corrosion kinetics of both steels
without NaCl coating followed the linear rate law at 200oC, but
followed the parabolic rate law at higher temperatures. However,
the corrosion kinetics of both steels with NaCl surface-coating
obeyed the parabolic rate law at all temperatures. The corrosion
rate constants of A516 were higher than those of SUS 304
stainless steel regardless of temperature and surface treatment.
The corroded scales formed on the steels without NaCl coating
and with NaClcoating were consisted of Fe2O3, Fe3O4, FeOOH and
FeCl3-nH2O (for A516) and ofFe2O3, NiCr2O4 and Ni(ClO4)-2.6H2O
(for SUS 304). The chlorine ion was always detected to be
located at the interface between the substrate and the corroded
scales on the steels with NaCl coating, which causes the
enhancement of the corrosion on the substrate. The hardness
distribution of the steels after welding treatment appeared tobe
different for both cases. The highest hardness-value of A516 was
located atthe welding zone, while the lowest one was in the
coarse-grain region of the heat-affected zone (HAZ). On the
contrary, the highest hardness-value of SUS 304 was in the
substrate, while the lowest one was located at the welding zone.
The rolling direction shows no effect on the mechanical
properties of both steels, however, welding treatment causes a
certain change. The results of the tensile test shows that both
yield strength (Y.S.) and ultimate tensile strength(U.T.S) of
A516 steel slightly increased after welding treatment but
elongationdecreased significantly (31%). On the other hand, all
values of the Y.S., U.T.S.and elongation of SUS 304 stainless
steel have a significant reduction afterwelding treatment.
| Identifer | oai:union.ndltd.org:TW/084NTOU0159002 |
| Date | January 1996 |
| Creators | Yu, Huei-Che, 游輝哲 |
| Contributors | Kai Wu, 開物 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 136 |
Page generated in 0.0016 seconds