Direct observation of Fe-Al-Zn ternary intermetallic compound and its transformation during the early stage of hot-dip galvanizing

Author(s):  
C. S. Lin ◽  
W. A. Chiou ◽  
M. Meshii

The galvannealed steel sheets have received ever increased attention because of their excellent post-painting corrosion resistance and good weldability. However, its powdering and flaking tendency during press forming processes strongly impairs its performance. In order to optimize the properties of galvanneal coatings, it is critical to control the reaction rate between solid iron and molten zinc.In commercial galvannealing line, aluminum is added to zinc bath to retard the diffusion rate between iron and zinc by the formation of a thin layer of Al intermetallic compound on the surface of steel at initial hot-dip galvanizing. However, the form of this compound and its transformation are still speculated. In this paper, we report the direct observations of this compound and its transformation.The specimens were prepared in a hot-dip simulator in which the steel was galvanized in the zinc bath containing 0.14 wt% of Al at a temperature of 480 °C for 5 seconds and was quenched by liquid nitrogen.

2018 ◽  
Vol 739 ◽  
pp. 518-521 ◽  
Author(s):  
C.L. Yang ◽  
S. Tsuda ◽  
K. Umeo ◽  
T. Onimaru ◽  
W. Paschinger ◽  
...  

2021 ◽  
Vol 2057 (1) ◽  
pp. 012043
Author(s):  
I A Romanov ◽  
V I Borzenko ◽  
A N Kazakov

Abstract This work is devoted to an experimental study and comparison of the kinetics of hydrogen absorption by an intermetallic compound LaNi4.4Al0.3Fe0.3 in form of pure intermetallic compound free backfill and a compact based on it obtained by cold pressing with a spiral matrix of nickel-foam. To calculate the kinetic parameters of the hydrogen absorption reaction, the initial rates method is used. The PCT absorption isotherms are measured at temperatures of 313, 333, and 353 K. The experimental data are described with quite high confidence by the chosen model, which assumes that the reaction rate controlling step is the dissociative absorption of hydrogen on the surface of the a-phase. The rate of hydrogen absorption increases with increasing pressure drop and temperature. It is shown that the rate of hydrogen absorption by the sample of pure IMC is significantly less dependent on temperature compared to the compact sample. In addition, the reaction rate at temperatures of 313 and 333 K is higher for the free backfill sample, and at 353 K it is higher for the metal hydride compact. The values of the absorption constant and the activation energy of the hydrogen absorption reaction are determined for both samples.


1998 ◽  
Vol 95 (2) ◽  
pp. 175-181 ◽  
Author(s):  
Tomohiro Akiyama ◽  
Hiromichi Isogai ◽  
Jun-ichiro Yagi

2010 ◽  
Vol 645-648 ◽  
pp. 813-816 ◽  
Author(s):  
Keiko Kouda ◽  
Yasuto Hijikata ◽  
Hiroyuki Yaguchi ◽  
Sadafumi Yoshida

We have investigated the oxidation process of SiC (000-1) C-face at low oxygen partial pressures using an in-situ spectroscopic ellipsometry. The oxide growth rate decreased steeply at the early stage of oxidation and then slowly decreased with increasing oxide thickness. The initial oxide growth rate was almost proportional to the oxygen partial pressure for both the polar directions. This result suggests that the initial interfacial reaction rate is constant regardless of the concentration of oxidants reaching the interface.


2013 ◽  
Vol 331 ◽  
pp. 443-447 ◽  
Author(s):  
Fu Tao Han ◽  
Zuo Cheng Wang ◽  
Cai Nian Jing ◽  
Xiao Min Liu ◽  
Jie Su ◽  
...  

Microstructure and microtexture evolution during batch annealing of warm-rolled Ti-IF steel sheets were investigated in this paper. It was founded that α fiber texture and the relatively weak γ fiber texture were formed in warm-rolled and air-cooled Ti-IF steel sheets. In the early stage of recrystallization, the {111} recrystallization texture was formed from the deformed {111} grains in warm-rolled Ti-IF steels. In the later stage of recrystallization, the α fiber texture was consumed and the γ fiber texture in recrystallized grains was further developed. The main recrystallization texture characteristics of warm-rolled Ti-IF steel sheets had been decided in the early stages of recrystallization, and the oriented nucleation mechanism played a leading role in the formation of recrystallization texture in warm-rolled Ti-IF steel sheets.


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