scholarly journals The Effect of Microstructural Differences on NA2SO4-Induced Corrosion of Superalloy CMSX-4 at High Temperatures

1997 ◽  
Author(s):  
Ming Li ◽  
Vimal H. Desai ◽  
N. Sastry Cheruvu
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Single Crystal ◽  
Hot Corrosion ◽  
Eutectic Structure ◽  
Short Exposure ◽  
Short Exposure Time ◽  
Heat Treated ◽  
Large Casting ◽  
Dendritic Arm Spacing

Single crystal (SC) nickel based superalloys have been used in aero engine applications for a long time. The SC casting techniques are not yet widely used in the land based engine components because of their much larger size which makes casting and the subsequent heat treatment more difficult. In large casting, microporosity and elemental segregation are more severe. The γ/γ′ eutectic structure and dendritic arm spacing are also larger due to large casting size. All these defects will affect the heat treatment process and the subsequent service properties, including the resistance to oxidation and hot corrosion. In this work, as-cast and heat treated CMSX-4 specimens from small and large blades were used to study the effects of cast defects and heat treatment on Na2SO4 -induced hot corrosion resistance of the single crystal superalloy. The tests were carried out between 900 to 1000°C, for times ranging than 10 to 600 hours in the presence of a Na2SO4 deposit. The specimens from as-cast large blade underwent catastrophic attack after a short exposure time. But the initiation time for catastrophic attack approximately doubled in the case of wholly solution heat treated specimens. It is thus likely that although the hot corrosion resistance of this single crystal material is not as good as that of IN738, proper heat treatment can improve its hot corrosion resistance.

Heat Treatment Influence on the Corrosion Resistance of a Cu-Al-Fe-Mn Bronze

2018 ◽  
Vol 69 (5) ◽  
pp. 1055-1059 ◽  
Author(s):  
Mariana Ciurdas ◽  
Ioana Arina Gherghescu ◽  
Sorin Ciuca ◽  
Alina Daniela Necsulescu ◽  
Cosmin Cotrut ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Structural Changes ◽  
Heating Temperature ◽  
Galvanic Corrosion ◽  
Cooling Water ◽  
Open Circuit ◽  
Water Quenching ◽  
Heat Treated ◽  
Different Temperatures

Aluminium bronzes are exhibiting good corrosion resistance in saline environments combined with high mechanical properties. Their corrosion resistance is obviously confered by the alloy chemical composition, but it can also be improved by heat treatment structural changes. In the present paper, five Cu-Al-Fe-Mn bronze samples were subjected to annealing heat treatments with furnace cooling, water quenching and water quenching followed by tempering at three different temperatures: 200, 400 and 550�C. The heating temperature on annealing and quenching was 900�C. The structure of the heat treated samples was studied by optical and scanning electron microscopy. Subsequently, the five samples were submitted to corrosion tests. The best resistance to galvanic corrosion was showed by the quenched sample, but it can be said that all samples are characterized by close values of open-circuit potentials and corrosion potentials. Concerning the susceptibility to other types of corrosion (selective leaching, pitting, crevice corrosion), the best corrosion resistant structure consists of a solid solution, g2 and k compounds, corresponding to the quenched and 550�C tempered sample.

EFFECT OF HEAT TREATMENT ON MICROSTRUCTURE AND CORROSION RESISTANCE OF Ni-B-W-Mo COATING DEPOSITED BY ELECTROLESS METHOD

2018 ◽  
Vol 25 (08) ◽  
pp. 1950023 ◽  
Author(s):  
ARKADEB MUKHOPADHYAY ◽  
TAPAN KUMAR BARMAN ◽  
PRASANTA SAHOO
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Electrochemical Techniques ◽  
Sodium Molybdate ◽  
Medium Carbon Steel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solid Solution Strengthening ◽  
Heat Treated ◽  
Electroless Coatings

The present work reports the deposition of a quaternary Ni-B-W-Mo coating on AISI 1040 medium carbon steel and its characterization. Quaternary deposits are obtained by suitably modifying existing electroless Ni-B bath. Composition of the as-deposited coating is analyzed by energy dispersive X-ray spectroscopy. The structural aspects of the as-deposited and coatings heat treated at 300[Formula: see text]C, 350[Formula: see text]C, 400[Formula: see text]C, 450[Formula: see text]C and 500[Formula: see text]C are determined using X-ray diffraction technique. Surface of the as-deposited and heat-treated coatings is examined using a scanning electron microscope. Very high W deposition could be observed when sodium molybdate is present in the borohydride-based bath along with sodium tungstate. The coatings in their as-deposited condition are amorphous while crystallization takes place on heat treatment. A nodulated surface morphology of the deposits is also observed. Vickers’ microhardness and crystallite size measurement reveal inclusion of W and Mo results in enhanced thermal stability of the coatings. Solid solution strengthening of the electroless coatings by W and Mo is also observed. The applicability of kinetic strength theory to the hardening of the coatings on heat treatment is also investigated. Corrosion resistance of Ni-B-W-Mo coatings and effect of heat treatment on the same are also determined by electrochemical techniques.

scholarly journals Evaluation of Heat-Treated AISI 316 Stainless Steel in Solar Furnaces to Be Used as Possible Implant Material

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 581
Author(s):  
Ioan Milosan ◽  
Monica Florescu ◽  
Daniel Cristea ◽  
Ionelia Voiculescu ◽  
Mihai Alin Pop ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Solar Energy ◽  
Heat Treatments ◽  
Solar Furnace ◽  
316 Stainless Steel ◽  
Heat Treated ◽  
Aisi 316 Stainless Steel ◽  
Aisi 316

The appropriate selection of implant materials is very important for the long-term success of the implants. A modified composition of AISI 316 stainless steel was treated using solar energy in a vertical axis solar furnace and it was subjected to a hyper-hardening treatment at a 1050 °C austenitizing temperature with a rapid cooling in cold water followed by three variants of tempering (150, 250, and 350 °C). After the heat treatment, the samples were analyzed in terms of hardness, microstructure (performed by scanning electron microscopy), and corrosion resistance. The electrochemical measurements were performed by potentiodynamic and electrochemical impedance spectroscopy in liquids that simulate biological fluids (NaCl 0.9% and Ringer’s solution). Different corrosion behaviors according to the heat treatment type have been observed and a passivation layer has formed on some of the heat-treated samples. The samples, heat-treated by immersion quenching, exhibit a significantly improved pitting corrosion resistance. The subsequent heat treatments, like tempering at 350 °C after quenching, also promote low corrosion rates. The heat treatments performed using solar energy applied on stainless steel can lead to good corrosion behavior and can be recommended as unconventional thermal processing of biocompatible materials.

Wear and Corrosion Resistance of Electroless Nickel-Boron Coated Mild Steel

2010 ◽  
Vol 638-642 ◽  
pp. 846-851 ◽  
Author(s):  
Abdoul Fatah Kanta ◽  
Véronique Vitry ◽  
Fabienne Delaunois
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Mild Steel ◽  
Electrochemical Impedance ◽  
Electroless Nickel ◽  
Uncoated Steel ◽  
Wear And Corrosion ◽  
Heat Treated ◽  
Wear And Corrosion Resistance ◽  
Hardening Heat Treatment

Nickel-boron coatings were synthesized on mild steel by the electroless deposition method. Some of the coatings were submitted to a hardening heat treatment at 400°C during 1 hour in an atmosphere containing 95% Ar and 5% H2. Uncoated steel, treated and untreated samples were submitted to the Taber abrasion test to assess their wear resistance. The wear track was then examined by SEM and roughness measurement. The Taber Wear Index of untreated samples was slightly better than that of steel but heat treated samples attained TWI as small as 13. The corrosion resistance of the samples was investigated by the way of polarization and electrochemical impedance spectroscopy (EIS) and the influence of the heat treatment was observed.

Characterization of Ni-P and Ni-P-Al2O3 Heat Treated Layers

2017 ◽  
Vol 1143 ◽  
pp. 26-31
Author(s):  
Lucica Balint ◽  
Gina Genoveva Istrate
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Composite Coatings ◽  
Treatment Temperature ◽  
Initial State ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Before And After

Research has shown the relationship among hardness, usage and corrosion resistance Ni-P-Al2O3 composite coatings on steel support heat treated. The electroless strips were heat treated at 200°C, 300°C, 400°C, 500°C and 600°C. Further studies on corrosion, hardness and usage revealed changes in properties, compared to the initial state, both on the strips coated with Ni-P and the ones coated with Ni-P-Al2O3 composite. The samples have been studied before and after the heat treatment via Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Analysis (EDX) and X-Ray Diffraction (XRD). The results show that untreated Ni-P layers exhibit strong corrosion resistance, while hardness and usage increase with heat treatment temperature, with a peak at 400 °C. Using suspended particles co-deposition, led to new types of layers, some with excellent hardness and usage properties. Corrosion resistance increase with heat treatment. Coating layers can be adjusted to the desired characteristics, by selecting proper parameters for the expected specific results.

scholarly journals EFFECT OF HEAT TREATMENT AND PLASMA NITRIDING ON CORROSION RESISTANCE OF 440B MARTENSITIC STAINLESS STEEL

2013 ◽  
Vol 7 (3) ◽  
pp. 155-159 ◽  
Author(s):  
Magdalena Łępicka ◽  
Małgorzata Grądzka-Dahlke
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Plasma Nitriding ◽  
Steel Corrosion ◽  
Surgical Instruments ◽  
High Wear Resistance ◽  
Heat Treated ◽  
Conventional Heat Treatment ◽  
Steel Corrosion Resistance

Abstract Reliability and durability assurance poses a serious challenge for surgical instruments manufacturers. Hard working conditions, such as intermittent contact with body fluids and hard bone tissues, as well as necessity to undergo frequent sterilisation processes, induce constant research into solutions capable of ensuring high wear resistance while maintaining satisfactory imperviousness to corrosion. Plasma nitriding is marked as the modern corrosion resistance improving method suitable for surgical instruments steels. The paper presents findings from the heat treated and plasma nitrided AISI 440B (PN EN or DIN X90CrMoV18) steel corrosion resistance studies. Three conventionally heat treated (quenched with tempering in 250, 390 or 605°C) and three additionally plasma nitrided in N2:H2 reaction gas mixture (50:50, 35:65 and 20:80 ratio, respectively) specimens groups were examined. Furthermore, the authors evaluated the effect of machining - polishing and sandblasting - on investigated steel corrosion resistance. Microscopic observations and electrochemical corrosion tests were performed using a variety of analytical techniques. Results showed that, in comparison to conventional heat treatment, plasma nitriding of 440B stainless steel does not significantly affect its corrosive characteristics as far as the uniform nitride layer over the entire detail surface is obtained. The layer heterogeneity results in intensification of corrosion processes, making the material even more susceptible to corrosion than after conventional heat treatment, and contributing to severe, visible even with the unaided eye damages development.

Effect of Re and Ta on Hot Corrosion Resistance of Nickel-base Single Crystal Superalloys

2016 ◽  
pp. 177-185 ◽  
Author(s):  
J.X. Chang ◽  
D. Wang ◽  
G. Zhang ◽  
L.H. Lou ◽  
J. Zhang
Keyword(s):  
Corrosion Resistance ◽  
Single Crystal ◽  
Hot Corrosion ◽  
Nickel Base

scholarly journals Effects of Different Surface Native Pre-Oxides on the Hot Corrosion Properties of Nickel-Based Single Crystal Superalloys

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5774
Author(s):  
Zehao Chen ◽  
Shusuo Li ◽  
Mengmeng Wu ◽  
Yanling Pei ◽  
Shengkai Gong ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Single Crystal ◽  
Hot Corrosion ◽  
Corrosion Properties ◽  
Al2o3 Layer ◽  
Nickel Based Superalloy ◽  
Surface Oxides ◽  
The Relationship ◽  
Positive Effect

A study is carried out on the effect of different surface native pre-oxides on hot corrosion of single crystal nickel-based superalloy at 900 °C. The effect of different oxides formed by different superalloys through pre-oxidation on hot corrosion is verified by normal hot corrosion and tube sealing experiments. The relationship between different surface oxides and the effect of different surface oxides layer on the hot corrosion properties of alloys are studied. In summary, the stable and dense surface pre-Al2O3 layer which can be obtained by pre-oxidation has an obvious positive effect on the improvement of superalloy hot corrosion resistance in reaction. In addition, the internal sulfides are analyzed in depth, and the relationship between Cr, Mo, O and S is discussed in detail.

Effect of non-conventional heat treatment of API X60 pipeline steel on corrosion resistance and stress corrosion cracking susceptibility

2019 ◽  
Vol 66 (3) ◽  
pp. 274-285 ◽  
Author(s):  
Luis Ricardo Jacobo ◽  
Rafael Garcia ◽  
Victor Hugo Lopez ◽  
Antonio Contreras
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Strain Rate ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Activation Process ◽  
Content Type ◽  
Heat Treated ◽  
Conventional Heat Treatment

Purpose The purpose of this paper is to study the effect of heat treatment (HT) applied to an API X60 steel in corrosion resistance and stress corrosion cracking (SCC) susceptibility through slow strain rate tests (SSRT) in NS4 solution and congenital water (CW) to assess external and internal SCC, respectively. Design/methodology/approach API X60 steel was heat treated at a temperature of 1,200°C for 30 min followed by water quenching. Specimens from this steel were machined according to NACE TM 198. SSRT were performed in a constant extension rate tests (CERT) machine at room temperature at a strain rate of 1 × 10–6 s–1. For this purpose, a glass cell was used. Corrosion behavior was evaluated through polarization curves (PCs). Findings The SCC index obtained from SSRT indicates that the steel heat treated could be susceptible to SCC in CW and NS4 solution; the mechanism of SCC was hydrogen embrittlement. Thus, CW may promote the SCC phenomenon in pipelines. HT improves the steel corrosion resistance. Higher corrosion rate (CR) was observed when the steel is exposed to CW. The corrosion process in X60 steel shows that the oxidation reaction in the anodic branch corresponds to an activation process, and the cathode branches reveal a diffusion process. Originality/value The purpose of the heat treatment applied to X60 steel was to generate a microstructure of acicular ferrite to improve the corrosion resistance and SCC behavior.

scholarly journals Effect of Experimental Aging on the Performance of Al-7.9Mg-13.3Zn and Al-10.5Mg-8.6Zn Alloys as Sacrificial Anodes

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 863 ◽  
Author(s):  
Hernández ◽  
Torres ◽  
Serna ◽  
Mayén ◽  
Campillo
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Electrochemical Techniques ◽  
Metallographic Analysis ◽  
Low Density ◽  
Sacrificial Anodes ◽  
Corrosion Rates ◽  
Heat Treated ◽  
Corrosion Mechanisms ◽  
Zn Alloys

Light aluminum alloys have a great importance in industry owing to generally accessible costs, low density, good machinability, and corrosion resistance under certain environments. The present work studies aging treatments that preform important roles on the distribution and microstructural changes of two AlMg-Zn alloys, and the resulting effect on the corrosion behavior. The experimental AlMg-Zn alloys were cast and then heat treated at 200 °C, after the solubilization treatments were made, using different treatment times. These alloys showed important changes in their corrosion mechanisms, but mainly, corrosion started at AlxMgyZnz complex phases in both alloys. The optimal corrosion rates were reached after 5 and 24 hours of heat treatment. These results were obtained through electrochemical techniques in NaCl solutions, and by metallographic analysis using SEM and optical microscopy.

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