Microstructure, Mechanical Properties and Fracture Behavior of Magnesium/Steel Bimetal Using Compound Casting Assisted with Hot-Dip Aluminizing

Wenming Jiang,Haixiao Jiang,Guangyu Li,Feng Guan,Junwen Zhu,Zitian Fan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8

In this work, microstructure, mechanical properties and fracture behavior of the magnesium/steel bimetal using compoundcasting assisted with hot-dip aluminizing were investigated, and the interface bonding mechanism of the magnesium/steelbimetal were also analyzed. The results indicate that the magnesium/steel bimetal obtained without hot-dip aluminizing hadlarger gaps through the whole interface without reaction layers between magnesium and steel, leading to a poor mechanicalbonding. After the steel substrate was hot-dip aluminized, an intermetallic layer along with an Al topcoat layer wereformed on the surface of the steel substrate, and the intermetallic layer was constituted by Fe2Al5,τ10-Al9Fe4Si3, FeAl3andτ6-Al4.5FeSi phases. In the case of the magnesium/steel bimetal obtained with hot-dip aluminizing, a compact and uniforminterface layer with an average thickness of about 17 μm that consisted of Fe2Al5,τ10-Al9Fe4Si3, FeAl3and Al12Mg17intermetalliccompounds was formed between the magnesium and the steel, obtaining a superior metallurgical bonding. The interfacelayer had much higher nano-hardnesses compared to the magnesium and steel matrixes, and its average nano-hardness wasup to 11.1 GPa, while there were respectively 1.1 and 4.2 GPa for the magnesium and steel matrixes. The shear strength ofthe magnesium/steel bimetal with hot-dip aluminizing reached to 23.3 MPa, which increased by 8.59 times than that of thecomposites without hot-dip aluminizing. The fracture of the magnesium/steel bimetal with hot-dip aluminizing representeda brittle fracture nature, initiating from the interface layer.

Incoloy 909 합금의 최적 알루미나이징 확산 코팅

권순우(S.W. Kwon),윤재홍(J.H. Yoon),주윤곤(Y.K. Joo),조동율(T.Y. Cho),안진성(J.S. Ahn),박봉규(B.K. Park) 한국표면공학회 2007 한국표면공학회지 Vol.40 No.4

An Fe-Ni-Co based superalloy Incoloy 909 (Incoloy 909) has been used for gas turbine engine component material. This alloy is susceptible to high temperature oxidation and corrosion because of the absence of corrosion resistant Cr. For the improvement of durability of the component of Incoloy 909 aluminizing-chromate coating by pack cementation process has been investigated at relatively low temperature of about 550℃ to protect the surface microstructure and properties of lncoloy 909 substrate. As a previous study to aluminizing-chromate coating by pack cementation of Incoloy 909, the optimal aluminizing process has been investigated. The size effects of source AI powder and inert filler Al₂O₃ powder and activator selection have been studied. And the dependence of coating growth rate on aluminizing temperature and time has also been studied. The optimal aluminizing process for the coating growth rate is that the mixing ratio of source Al powder, activator NH₄Cl and filler Al₂O₃ are 80%, 1% and 19% respectively at aluminizing temperature 552℃ and time 20 hours.

주철 알루미늄 합금의 Hot Dip Aluminizing시 흑연 및 금속간화합물 층의 형성 거동

한광식 ( Kwang Sic Han ),강용주 ( Yong Joo Kang ),강문석 ( Mun Seok Kang ),강성민 ( Sung Min Kang ),김진수 ( Jin Su Kim ),손광석 ( Kwang Suk Son ),김동규 ( Dong Gyu Kim ) 한국주조공학회 2011 한국주조공학회지 Vol.31 No.2

Hot dip aluminizing (HDA) is widely used in industry for improving corrosion resistance of material. The formation of intermetallic compound layers during the contact between dissimilar materials at high temperature is common phenomenon. Generally, intermetallic compound layers of Fe2Al5 and FeAl3 are formed at the Al alloy and Fe substrate interface. In case of cast iron, high contact angle of graphite existed in the matrix inhibits the formation of intermetallic compound layer, which carry with it the disadvantage of a reduced reaction area and mechanical properties. In present work, the process for the removal of graphite existed on the surface of specimen has been investigated. And also HDA was proceeded at 800oC for 3 minutes in aluminum alloy melt. The efficiency of graphite removal was increased with the reduction of particle size in sanding process. Graphite appears to be present both in the region of melting followed by re-solidification and in the intermetallic compound layer, which could be attributed to the fact that the surface of cast iron is melted down by the formation of low melting point phase with the diffusion of Al and Si to the cast iron. Intermetallic compound layer consisted of Fe(Al,Si)3 and Fe2Al5Si, the layer formed at cast iron side contained lower amount of Si.

Al-Ti 혼합 분말 슬러리를 이용한 강의 알루미나이징처리 방법

이영기,김정열,이유기,Lee, Young-Ki,Kim, Jung-Yeul,Lee, You-Kee 한국재료학회 2009 한국재료학회지 Vol.19 No.4

In this study, we attempted to develop a convenient aluminizing process, using Al-Ti mixed slurry as an aluminum source, to control the Al content of the aluminized layer as a result of a one-step process and can be widely adopted for coating complex-shaped components. The aluminizing process was carried out by the heat treatment on disc and rod shaped S45C steel substrates with Al-Ti mixed slurries that were composed of various mixed ratios (wt%) of Al and Ti powders. The surface of the resultant aluminized layer was relatively smooth with no obvious cracks. The aluminized layers mainly contain an Fe-Al compound as the bulk phase. However, the Al concentration and the thickness of the aluminized layer gradually decrease as the Ti proportion among Al-Ti mixed slurries increases. It has also been shown that the Al-Ti compound layer, which formed on the substrate during heat treatment, easily separates from the substrate. In addition, the incorporation of Ti into the substrate surface during heat treatment was not observed.

Aluminizing and Boroaluminizing Treatments of Mar-M247 and Their Effect on Hot Corrosion Resistance in Na₂SO₄-NaCl Molten Salt

Cho, J.H.,Kim, T.W.,Son, K.S.,Yoon, J.H.,Kim, H.S.,Leisk, G.G.,Mitton, D.B.,Latanision, R.M. 대한금속재료학회 2003 METALS AND MATERIALS International Vol.9 No.3

The effect of surface modifications of Mar-M247 superalloy on hot corrosion resistance was examined in Na₂SO₄-NaCl molten salt. The Mar-M247 was aluminized and boroaluminized by pack cementation in Ar and underwent a cyclic hot corrosion test in Na₂SO₄-NaCl molten salt. The XRD results showed that a Ni2Al3 phase was formed between the aluminized layer and the substrate when the surface modification temperature was below 1273 K. However, a NiAl phase formed when the temperature was above 1273 K. The intensity of the XRD peak in the NiAl phase increased after post heat treatment. Hot corrosion resistance increased for the specimens containing NiAl rather than Ni₂Al₃ phase. The ductile NiAl phase suppressed the potential for crack initiation during thermal cycling. Post heat treatment increased the corrosion resistance of the aluminized layer for Mar-M247, which underwent surface modification at 1273 K and above. In the boroaluminized Mar-M247 specimens, corrosion resistance decreased as a result of the blocking of outward diffusion of Cr by boron and decreased cohesion between the oxide scale and the aluminized layer during thermal cycling.

Hot-Dip Aluminizing with Silicon and Magnesium Addition II. Effect on Corrosion Resistance

( Sun Kyu Kim ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.11

The effect of silicon and magnesium addition in a molten Al bath on the morphology and corrosion resistance of the Al coating layer of steel formed during hot-dip aluminizing was investigated at the temperatures of 700, 800, and 900 ℃ for the dipping time of 1-15 minutes. The thickness of the intermetallic layer decreased with an increasing Mg or Si content within a range of 0-1 at%. Addition of Si made the intermetallic layer thin whereas addition of Mg compensated for the decrease of the thickness significantly. The shape of the intermetallic layers became less irregular than that of the hot-dip aluminizing in pure aluminum. The results of immersion corrosion tests and electrochemical corrosion tests in a solution of 3 wt% NaCl showed that the corrosion resistance of the Al-1% Si-1% Mg coated steel had increased significantly over the Al coated steel. The open circuit potential changed from .0.56324 V (vs. SCE) to .0.48872 V (vs. SCE) and the corrosion current density decreased from 9.9991 μA/cm2 to 2.1160 μA/cm2. A salt fog spray test on these specimens also showed hot-dip aluminizing with Si and Mg addition increased the corrosion resistance significantly.

알루미나이징 처리한 2상 금속간화합물의 내산화 특성에 관한 연구

이상율,이정석 한국 항공대학교 항공산업기술연구소 1999 航空宇宙産業技術硏究所 硏究誌 Vol.9 No.-

Ni-32at%Al, Ni-32at%Al-0.5at%B 합금에 알루미나이징 처리를 행하여 산화특성을 분석하였다. 알루미나이징은 Al 높은 활동도로 Ni₂Al₃상을 형성시키며 후에 안정화처리로 Ni₂Al₃상을 NiAl상으로 변태시키는 high Al activity process를 이용하였다. 등온산화는 1100℃와 900℃에서 TGA를 이용하여 실시하였다. 등온산화결과 알루미나이징 처리한 합금이 처리하지 않은 합금에 비해 우수한 내산화성을 나타내었다. 형성층의 미세조직 관찰 및 상분석을 위하여 SEM, XRD 및 EDS를 이용하였고 1100℃와 TGA를 이용하여 900℃에서 등온산화시험을 실시하였다. 등온산화시험결과 알루미나이징 처리한 합금이 처리하지 않은 합금에 비해 우수한 내산화성을 나타내었다. 그 이유는 고온산화시 NiAl층으로부터 지속적인 Al공급으로 치밀하고 안정한 α-Al₂O₃층을 형성하기 때문이다. In order to studied oxidation properties, the aluminizing treatment was performed on Ni-32at%Al and Ni-32at%Al-0.5at%B. High Al activity process is formed by inward diffusion of Al from coating media of sufficiently high Al activity to cause formation of the δ(Ni2A13) phase. Subsequent stabilizing heat treatment required for practical use of this type of coating cause some outward diffusion of Ni to form β(NiAl) phase. Microstructure of aluminized and oxidized layer was characterized by SEM, XRD and EDS analysis. Isothermal oxidation tests were made at 1100℃ in air and at 900℃ in air by using TGA. According to the Isothermal oxidation test results, the aluminizing treated Ni-32at%Al and Ni32at%Al-0.5at%B was excellent oxidation resisrence than no treated The reason why α-Al203 layer forms dense and stable scale is that NiAl layer contineously supplies α-Al203 layer with Al.

팩 세멘테이션법에 의한 Incoloy 909 합금의 알루미나이징

안진성(Jin-Sung Ahn),권순우(Soon-Woo Kwon),윤재홍(Jae-Hong Yoon),박봉규(Bong-Gyu Park) 한국표면공학회 2006 한국표면공학회지 Vol.39 No.4

Incoloy alloy 909 is an Fe-Ni-Co based superalloy that is attractive for gas turbine engine applications. The absence of chromium, however, makes the alloy more susceptible to oxidation in high temperature. To improve the oxidation resistance aluminizing was performed by high activity low temperature pack cementation process. Aluminizing condition was examined with different times and temperatures. Optimum aluminizing conditions were at the temperature of 552℃ for 20 hrs. In the optimized condition, the thickness of the aluminized layer was about 20 ㎛. Also, the aluminized layer made the alloy to increase the resistance to the corrosion

Aluminizing and Corrosion of Carbon Steels in N₂/0.5%H₂S Gas at 650-850℃

Muhammad Ali Abro,Dong Bok Lee 한국표면공학회 2015 한국표면공학회지 Vol.48 No.3

The effect of hot-dip aluminizing on the corrosion of the low carbon steel was studied at 650-850℃ for 20-50 h in N2/0.5% H2S gas. The aluminized steel consisted primarily of the Al topcoat and the underlying Al-Fe alloy layer. Aluminizing drastically improved the corrosion resistance by forming the α-Al2O3 surface scale. Without aluminizing, the steel formed nonadherent, fragile, thick scales, which consisted of FeS as the major phase and iron oxides such as FeO, Fe3O4 and Fe2O3 as minor ones.

Effect of Aluminizing Treatment on the Oxidation Properties of 12Cr Heat Resisting Steel

김재환,왕제필,강창룡 대한금속·재료학회 2011 METALS AND MATERIALS International Vol.17 No.6

In order to investigate the effect of aluminization on the oxidation properties of 12Cr martensitic heat resisting steel, a specimen was prepared by forging after centrifugal casting. After aluminizing treatment under various conditions, scanning electron microscopy observation, and hardness, line profile and x-ray diffraction analysis of the alloy layer were performed. The results confirmed that the thickness of the layer of Al13Fe4, with a Vickers hardness of over 880, increased with increasing aluminizing temperature and time. Moreover, it was concluded from the results of the oxidation experiment that the oxidation properties of the aluminized specimen were improved by up to approximately 30 %.