Effect of Thermochemical Treatment on the Structure and Mechanical Properties of Materials Based on Aluminum Oxide

2018 ◽  
Vol 284 ◽  
pp. 30-36
Author(s):  
Gennady G. Mikhailov ◽  
Tatiana M. Lonzinger ◽  
Vadim A. Skotnikov
Keyword(s):  
Heat Treatment ◽  
Structural Characteristics ◽  
Thermochemical Treatment ◽  
Grain Structure ◽  
Air Cooling ◽  
Damage And Failure ◽  
Heat Treated ◽  
Gas Atmosphere ◽  
Grinding Tool ◽  
Abrasive Paper

According to the standard process, normal electrocorundum is heat treated at 700°C in a rotating drum followed by air cooling. Such heat treatment increases the strength characteristics of abrasive grain. When abrasive paper made from grains with reduced brittleness is working, the effect of reducing the cutting ability due to damage and failure of the cutting surfaces is observed. An increase in the performance characteristics of the abrasive paper was studied by improving the self-sharpening of the grain. Improvement of this performance is achieved by thermochemical treatment in a regulated gas atmosphere and cooling according to a special schedule. Normal electrocorundum during heat treatment in an oxidizing atmosphere changes the structural characteristics due to the decomposition of a solid solution of Ti2O3 in α-Al2O3 by oxidation to TiO2. The formation of a block grain structure with microcracks increases the probability of chipping during the grinding tool operation and the appearance of new cutting surfaces.

Residual Stress Analysis Considering Phase Transformation and Transformation Plasticity for Heat-Treated Large Size Shaft

2016 ◽  
Vol 725 ◽  
pp. 647-652 ◽  
Author(s):  
Yusuke Yanagisawa ◽  
Yasuhiro Kishi ◽  
Katsuhiko Sasaki
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Phase Transformation ◽  
Air Cooling ◽  
Water Cooling ◽  
Stress Distributions ◽  
Transformation Plasticity ◽  
Large Size ◽  
Heat Treated ◽  
Good Agreement

The residual stress distributions of the forgings after both water-cooling and air-cooling were measured experimentally. The residual stress occurring during the heat-treatment was also simulated considering the phase transformation and the transformation plasticity. A comparison of the experiments with the simulations showed a good agreement. These results shows that the transformation plastic strain plays an important role in the heat treatment of large forged shafts.

New Results of the Heat-Treated CuZn39Pb3 Brass Behavior and Resistance to Cavitation Erosion

2021 ◽  
Vol 890 ◽  
pp. 173-180
Author(s):  
Ilare Bordeaşu ◽  
Nicușor Alin Sîrbu ◽  
Iosif Lazăr ◽  
Ion Mitelea ◽  
Cristian Ghera ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Cavitation Erosion ◽  
Stress Relief ◽  
Air Cooling ◽  
Water Cooling ◽  
Characteristic Parameters ◽  
Volume Heat ◽  
Heat Treated ◽  
Hardness Increase

The paper presents the results of the behavior and resistance to the erosion by vibrating cavitation of the CuZn39Pb3 brass, obtained by quenching the volume heat treatment from 800°C with water cooling, followed by the stress-relief to 250°C, with air cooling. Comparison with both the delivery status and the naval brass (used for ship propellers), based on the characteristic parameters values, recommended by the ASTM G32 standards and used in the Cavitation Laboratory of the Polytechnic University of Timisoara, shows that the hardness increase resulted from the heat treatment led to a significant increase of resistance to vibrating cavitation.

The Microstructure and Compression Behavior of Multi-Step Forging Ti-45Al-8Nb Alloy after Annealing at 1100 °C

2013 ◽  
Vol 747-748 ◽  
pp. 111-114
Author(s):  
Lin Song ◽  
Xiang Jun Xu ◽  
Jun Pin Lin ◽  
Lai Qi Zhang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Annealing Treatment ◽  
Air Cooling ◽  
Test Machine ◽  
Compressive Properties ◽  
Compression Behavior ◽  
Microstructure Change ◽  
Heat Treated ◽  
Before And After

Effects of annealing treatment on microstructure and the compressive properties of hot-worked Ti-45Al-8Nb-(W, B, Y) alloy were investigated. Microstructure of the extrusion plus multi-step forging pancake before and after heat treatment was analyzed by SEM and TEM, respectively. The annealing was conducted by holding samples at 1100°C for 2hrs, and followed by air cooling and furnace cooling. The mechanical properties were measured by Instron test machine. The microstructure evolution during compressive deformation was analyzed by TEM. The results showed that after the annealing the microstructure change could not be observed under SEM but can be observed under TEM. Many dislocation clusters were removed by heat treatment. The heat treated samples had similar compression behaviors with the pancake. TEM investigation showed that the numerous twin intersections occured in γ matrix during compression. The twin spaces tended to decrease as the deformation and the intersection increasing.

The Effect of Heat Treatment on Creep Resistance of Castings from the Modified Superalloy MAR-247

2013 ◽  
Vol 212 ◽  
pp. 229-236
Author(s):  
Marek Cieśla ◽  
Franciszek Binczyk ◽  
Marcin Mańka
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Creep Resistance ◽  
Nickel Superalloy ◽  
Grain Structure ◽  
Morphological Properties ◽  
High Temperature Creep ◽  
Temperature Creep ◽  
Fine Grain ◽  
Heat Treated

mpact of heat treatment on durability has been evaluated in this study in conditions of high-temperature creep of castings made from nickel superalloy MAR-247 post production rejects. Castings made in the processes of modification and filtration when pouring into moulds were subject to solubilization (1185°C/2 h) with subsequent ageing (870°C/20 h). It has been found on the basis of performed tests that in conditions of high-temperature creep at temperature 980°C with stress σ = 150 MPa the resistance of specimens of coarse-grain structure was significantly higher when compared to fine-grain material. The conditions of initiation and propagation of cracks in these specimens were analysed with consideration of morphological properties of material macro-, micro-and substructure. Moreover, it has been proven that creep resistance of heat treated MAR-247 superalloy significantly improves when compared to its condition after the process of modification only. Macrostructural changes in the MAR-247 superalloy that determine the increase of superalloy creep resistance after solubilization and ageing, as observed in the tests, were also examined.

Effect of Heat Treatment Conditions on Microstructure and Fracture Toughness of a Cast Ti-Al Alloy

2007 ◽  
Vol 26-28 ◽  
pp. 189-192
Author(s):  
Tae Kwon Ha ◽  
Jae Young Jung
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
High Purity ◽  
Vacuum Arc ◽  
Al Alloy ◽  
Air Cooling ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Treatment Conditions ◽  
Heat Treated

Ti-45.5Al-2Cr-4Nb-0.4B alloy was cast by vacuum arc melting at high purity Ar atmosphere using high purity sponge Ti, granular Al (99.99%), flake Nb (99.9%), lump Cr (99.9%) and TiB2 (99.5%) and subsequently heat-treated to obtain a couple of microstructures, i.e. lamellar and near γ. The heat treatment consisted of annealing at a high temperature (1200 ~ 1330oC) of different phase fields for 24 hrs and stabilizing at 900oC for 4 hrs followed by air cooling. Fracture toughness was measured on the specimens with different microstructures at room temperature. The value of KQ of specimen with fully lamella structure was obtained as 18.68 MPa √m, much higher than that of specimen with near γ structure (11.84 MPa √m). It was also revealed that the KQ value was decreased as the annealing temperature decreased.

Microstructural Evolution and Mechanical Properties of Modified 9%Cr-1%Mo Steel upon Isothermal Heat-Treatment

2005 ◽  
Vol 475-479 ◽  
pp. 81-84
Author(s):  
Sung Kang Hur ◽  
Kee Sam Shin ◽  
Jung Hoon Yoo ◽  
Ja Min Koo ◽  
Soo Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Mechanical Property ◽  
Microstructural Evolution ◽  
Heat Treating ◽  
Air Cooling ◽  
Isothermal Heat Treatment ◽  
Martensitic Structure ◽  
Heat Treated ◽  
Evolution Of Microstructure

The evolution of microstructure and its effects on the mechanical properties of modified 9%Cr-1%Mo steel during heat-treating at 1050°C for 15 min and then isothermal heat treatment at 380~760°C with subsequent air-cooling have been investigated. For the microstructural and mechanical property analyses, OM, SEM, EDS, XRD, hardness and impact tests were used. In accordance with the severity of the heat-treatment, the microstructure evolved from the untransformed martensite to the partially transformed dual phases of martensite and ferrite, and then fully transformed to ferrite. Impact values at ambient temperature for specimens isothermally heat-treated at 320 - 380°C, predominantly at about 350°C were lower than others’ with similar martensitic structure. The partially transformed specimens with dual phases of martensite and ferrite also showed lower impact values than samples with untransformed with martensitic, and transformed with ferritic structures.

scholarly journals Formability of Magnesium Alloys AZ80 and ZE10

2014 ◽  
Vol 622-623 ◽  
pp. 284-291 ◽  
Author(s):  
Timotius Pasang ◽  
V. Satanin ◽  
M. Ramezani ◽  
M. Waseem ◽  
Thomas Neitzert ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Magnesium Alloys ◽  
Strain Ratio ◽  
Grain Structure ◽  
Second Phase ◽  
Plastic Strain Ratio ◽  
Heat Treated ◽  
Second Phase Particles ◽  
Az80 Alloy ◽  
Hardening Coefficient

Formability of two magnesium alloys, namely, AZ80 and ZE10, has been investigated. Both alloys were supplied with a thickness of 0.8 mm. The grain structure of the as-received AZ80 alloy showed dislocations, twins and second-phase particles and-/or precipitates distributed uniformly within grains. These were not obvious on the ZE10 alloy. The investigations were carried out at room temperature for both alloys in the as-received and heat treated conditions (410oC for 1 hour followed by water quench). The heat treatment significantly changed the grain structure of the AZ80 alloy, but did not affect the ZE10 alloy apart from grain enlargement. The formability was studied on the basis of plastic strain ratio (r) and strain hardening coefficient (n) by means of tensile testing. In the as-received condition, the ZE10 alloy had a slightly better formability () than AZ80 alloy. Following heat treatment, however, the formability of the AZ80 alloy was improved significantly (by about 26%), while the ZE10 alloy did not show any significant change.

scholarly journals Effect of Pre-Weld Heat Treatment on Microstructure and Creep Strength of ICHAZ in Grade 91 Steel

2019 ◽  
Author(s):  
Yiyu Wang ◽  
Wei Zhang ◽  
Zhili Feng
Keyword(s):  
Heat Treatment ◽  
Base Metal ◽  
Creep Strength ◽  
Thermal Cycle ◽  
Air Cooling ◽  
Base Metals ◽  
Heat Treated ◽  
Welding Thermal Cycle ◽  
Grade 91 ◽  
Weld Heat

Abstract In this work, Grade 91 base metal was normalized with two different cooling conditions, water quenching and air cooling. The intercritical welding thermal cycle simulated by using the Gleeble system was applied to the heat-treated base metals to reproduce the intercritical heat-affected zone (ICHAZ). Microstructure, including precipitate and tempered martensite, of the base metal and ICHAZ was carefully characterized with advanced microscopy techniques. Creep strength of the simulated ICHAZs was evaluated at a high creep temperature of 650 °C with a stress of 100 MPa. A correlation between the microstructure and creep behavior of the ICHAZ is built to understand creep rupture mechanisms in the ICHAZ. The results show that more coarse carbides precipitated along the prior austenite grain boundaries after tempering in the water-quenched base metal. These carbides cannot be fully dissolved by the intercritical welding thermal cycle. The simulated ICHAZ generated from the water-quenched base metal underwent a higher grain recovery and growth during the typical post-weld heat treatment at 760 °C. Both simulated ICHAZs from two pre-weld heat treated base metals exhibit an extremely low creep resistance with a typical ductile fracture during creep testing. The faster grain growth and precipitate coarsening in the ICHAZ, simulated from the water-quenched base metal, made it even worse.

scholarly journals KARAKTERISTIK MIKROSTRUKTUR DAN FASA PADUAN Zr- 0,3%Nb-0,5%Fe-0,5%Cr PASCA PERLAKUAN PANAS DAN PENGEROLAN DINGIN

2015 ◽  
Vol 21 (2) ◽  
Author(s):  
Sungkono Sungkono ◽  
Masrukan Masrukan
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Cold Rolling ◽  
Retention Time ◽  
Cold Deformation ◽  
Grain Structure ◽  
Post Heat Treatment ◽  
Heat Treated ◽  
Fuel Elements

KARAKTERISTIK MIKROSTRUKTUR DAN FASA PADUAN Zr-0,3%Nb-0,5%Fe-0,5%Cr PASCA PERLAKUAN PANAS DAN PENGEROLAN DINGIN. Logam paduan Zr-Nb-Fe-Cr dikembangkan sebagai material kelongsong elemen bakar dengan fraksi bakar tinggi untuk reaktor daya maju. Dalam penelitian ini telah dibuat paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr yang mendapat perlakuan panas pada temperatur 650 dan 750°C dengan waktu penahanan 1–2 jam. Tujuan penelitian adalah mendapatkan karakter paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas dan pengerolan dingin yaitu mikrostruktur, struktur kristal dan fasa-fasa yang ada dalam paduan. Hasil penelitian menunjukkan bahwa paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas (650ºC, 1-2 jam) mempunyai struktur butir ekuiaksial dengan ukuran butir bertambah besar seiring dengan bertambahnya waktu penahanan. Sementara itu, pasca perlakuan panas (750ºC, 1-2 jam) terjadi perubahan mikrostruktur paduan dari butir ekuiaksial dan kolumnar menjadi butir ekuiaksial lebih besar. Paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas (650°C, 1 jam) dan (750°C, 1 jam) tidak dapat dirol dingin dengan reduksi tebal 5 – 10%, sedangkan pasca perlakuan panas (650ºC, 2 jam) dan (750°C, 1.5-2 jam) mampu menerima deformasi dingin dengan reduksi ketebalan 5-10% tanpa mengalami keretakan. Senyawa Zr2Fe, ZrCr2 dan FeCr teridentifikai dari hasil uji kristalografi paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr. MICROSTRUCTURE AND PHASE CHARACTERISTICSOF Zr-0.3%Nb-0.5%Fe-0.5%Cr ALLOY POST HEAT TREATMENT AND COLD ROLLING. Zr-Nb-Fe-Cr alloys was developed as fuel elements cladding with high burn up for advanced power reactors. In this research has been made of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy were heat treated with varying temperatures at650 and 750°C for 1 until 2 hours. The objectives of this research was to obtain the character of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy post heat treatment and cold rolling, microstructure nomenclature, crystal structure and phases that presents in the alloy. The results of this experiment showed that the microstructures of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy post heat treatment (650ºC, 1-2 hours) had equiaxial grain structure with an enlarged size with increasing of the retention time. Meanwhile, post heat treatment (750°C, 1-2 hours) occurred the microstructures evolution of alloy from equiaxial and columnar became equiaxial and columnar relatively large, and subsequently became the larger equiaxial grains. Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy post heat treatment (650°C, 2 h) and (750°C, 1.5-2 hours) can undergo cold deformation without cracking when thickness reduction between 5 to 10%.The phases formation of Zr2Fe, ZrCr2 and FeCr compounds can improve the mechanical strength and the corrosion resistance of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy.

Effect of Mg, Sr, Ti and Aging Parameters on the Mechanical Behavior of 319 Alloys in the T5 and T6 Heat Treatment

2012 ◽  
Vol 482-484 ◽  
pp. 2275-2288
Author(s):  
Saleh Alkahtani
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aging Treatment ◽  
Magnesium Content ◽  
Air Cooling ◽  
Particle Spacing ◽  
Sr Modification ◽  
Heat Treated ◽  
Negative Effect ◽  
Mg Content

In this work, the effect of metallurgical parameters (i.e. alloy chemistry and aging parameters) on the mechanical properties of 319 alloys was investigated, with the aim of adjusting these parameters to produce castings of suitable mechanical properties. An attempt has been made to quantify the effects of alloying elements (Mg, Sr, and Ti) and aging parameters on the mechanical properties of heat-treated (T5 and T6) 319 alloys. Exploring the heat treatment differences between T5 and T6 for 319 alloys would help in selecting the metallurgical conditions required to achieve the optimum and maximum mechanical properties. Aging treatments were carried out for 319 alloys in the T5- and T6-condition at 150°C, 180°C, 200°C, 220°C and 250°C for 4, 8, 16, 24 and 48 h, followed by air cooling. Aging treatment at a lower temperature of 150°C produces fine and dense precipitates having a smaller inter-particle spacing, while at higher aging temperatures, such as 250°C, the precipitates are coarser in size, less dense, and more widely dispersed. For 319 alloys, crack initiate and propagate mainly through the debonding of Si particles from the Al matrix and through the cleavage of β-iron intermetallics. Fracture of intermetallic phases in the interdendritic regions is mostly brittle, with the formation of microcracks at the Si, Cu, Fe-base intermetallics and aluminium interfaces. Experimental correlations of the results obtained from the mechanical properties measurements are analyzed and correlations that relate the alloying additions and heat treatment to the ultimate tensile strength (UTS), yield strength (YS) and total percent elongation (%E) of such alloys are found. Different levels of magnesium content (%Mg), Sr-modification (Sr-ppm), aging parameters (temperature and time) were tested. The effect of alloy additions (Mg, Sr and Ti) and aging heat treatment parameters (Temperature and Time) on the mechanical properties and alloy performance of cast and heat treated 319 alloys are investigated. It was found that the strength of 319 alloys increases with the magnesium content and decreases with the Sr-modification (Sr-ppm) and aging parameters (temperature and time). Increasing the Mg content in primary 319 alloys up to 0.45% enhances the alloy response to heat treatment in the T5 and T6 Tempers, more particularly, the T6 one. Sr-Modification of high Mg content 319 alloy in amounts of ~360 ppm leads to a noticeable decline in alloy strength due to porosity formation which counteracts the beneficial effect of the modification. Sr-modification has a negative effect on the % elongation results of Mg-content 319 alloys due to the Mg-Sr interaction in the aged-T6 conditions. However, grain refining of the Mg and Sr content 319 alloys produce sounder castings with finer grain sizes

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