scholarly journals Ultrafine Ductile and Austempered Ductile Irons by Solidification in Ultrasonic Field

2021 ◽  
Author(s):  
M. Ahmed ◽  
E. Riedel ◽  
M. Kovalko ◽  
A. Volochko ◽  
R. Bähr ◽  
...  
Keyword(s):  
Ductile Iron ◽  
Acoustic Waves ◽  
Iron Alloy ◽  
Austempered Ductile Iron ◽  
Maximum Speed ◽  
Spheroidal Graphite ◽  
Dual Phase ◽  
Nodule Count ◽  
The Matrix ◽  
Sg Iron

AbstractIn this research, ultrasonic melt treatment (UST) was used to produce a new ultrafine grade of spheroidal graphite cast iron (SG iron) and austempered ductile iron (ADI) alloys. Ultrasonic treatment was numerically simulated and evaluated based on acoustic wave streaming. The simulation results revealed that the streaming of the acoustic waves propagated as a stream jet in the molten SG iron along the centerline of the ultrasonic source (sonotrode) with a maximum speed of 0.7 m/s and gradually decreased to zero at the bottom of the mold. The metallographic analysis of the newly developed SG iron alloy showed an extremely ultrafine graphite structure. The graphite nodules’ diameter ranging between 6 and 9 µm with total nodule count ranging between 900 to more than 2000 nodules per mm2, this nodule count has never been mentioned in the literature for castings of the same diameter, i.e., 40 mm. In addition, fully ferritic matrix was observed in all UST SG irons. Further austempering heat treatments were performed to produce different austempered ductile iron (ADI) grades with different ausferrite morphologies. The dilatometry studies for the developed ADI alloys showed that the time required for the completion of the ausferrite formation in UST alloys was four times shorter than that required for statically solidified SG irons. SEM micrographs for the ADI alloys showed an extremely fine and short ausferrite structure together with small austenite blocks in the matrix. A dual-phase intercritically austempered ductile iron (IADI) alloy was also produced by applying partial austenitization heat treatment in the intercritical temperature range, where austenite + ferrite + graphite phases coexist. In dual-phase IADI alloy, it was established that introducing free ferrite in the matrix would provide additional refinement for the ausferrite.

scholarly journals Machinability and related properties of austempered ductile iron: A review

2018 ◽  
Vol 12 (4) ◽  
pp. 4180-4190
Author(s):  
Ananda Hegde ◽  
Sathyashankara Sharma ◽  
Gowri Shankar M. C
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Wear Resistance ◽  
Ductile Iron ◽  
High Hardness ◽  
Austempered Ductile Iron ◽  
Spheroidal Graphite ◽  
Light Weight ◽  
Sg Iron

When the ductile iron which is also known as Spheroidal Graphite (SG) iron, is subjected to austempering heat treatment, the material is known as austempered ductile iron (ADI). This material has good mechanical properties and has various applications in different fields. This revolutionary material with its excellent combination of strength, ductility, toughness and wear resistance has the potential to replace some of the commonly used conventional materials such as steel, aluminium and other light weight alloys as it offers production advantage as well. One of the problems encountered during manufacturing is machining of ADI parts owing to its high hardness and wear resistance. Many researchers over a period of time have reported the machinability aspects of the ADI. This paper presents a review on the developments made on the machinability aspects of ADI along with other mechanical properties.

Assessment of Machining Characteristics of Austempered Ductile Iron

2010 ◽  
Vol 97-101 ◽  
pp. 2036-2039 ◽  
Author(s):  
Ashwin Polishetty ◽  
Guy Littlefair
Keyword(s):  
Surface Texture ◽  
Ductile Iron ◽  
Cutting Parameters ◽  
Cutting Fluid ◽  
Austempered Ductile Iron ◽  
Spheroidal Graphite ◽  
Surface Texture Analysis ◽  
Machining Characteristics ◽  
Stage Heat Treatment ◽  
Cutting Speeds

Austempered Ductile Iron (ADI) is a modified Spheroidal Graphite Iron (SGI) produced by applying a two-stage heat treatment cycle of austenitising and austempering. The microstructure of ADI also known as “ausferrite” consists of ferrite, austenite and graphite nodules. Machining ADI using conventional techniques is often problematic due to the microstructural phase transformation from austenite to martensite. Machining trials consisted of drilling ADI-Grades900, 1050, 1200 and 1400 using inserted (TiAlN PVD coated) type drills. The cutting parameters selected were; cutting speeds [m/min] of 30 and 40; penetration rates [mm/rev] of 0.1 and 0.2; to a constant depth of 20mm. The machining characteristics of ADI are evaluated through surface texture analysis and microhardness analysis. These results indicate that microhardness is modified during machining and surface texture is improved using a cutting fluid.

scholarly journals Microstructure and fracture mode of unalloyed dual phase austempered ductile iron

2021 ◽  
pp. 27-27
Author(s):  
Petar Janjatovic ◽  
Cekic Eric ◽  
Dragan Rajnovic ◽  
Sebastian Balos ◽  
Vencislav Grabulov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ductile Iron ◽  
Tensile Testing ◽  
Dual Phase ◽  
Material Microstructure ◽  
Two Phase ◽  
Major Disadvantage ◽  
The Matrix ◽  
Type Of Fracture ◽  
Scanning Electron

Dual phase ADI material microstructure consists of different amounts and morphologies of ausferrite and free ferrite, obtained by subjecting ductile iron to specific heat treatment. As such, its strength is lower compared to comparable ADI materials, but exhibiting a higher ductility, the major disadvantage of ADI. In the current study, an unalloyed ductile iron was intercritical austenitised in two-phase regions (?+?) at four temperatures from 840 to 780?C for 2 hours and austempered at 400?C for 1 hour to obtain dual phase ADI with different percentages of free ferrite and ausferrite. Metallographic and fracture studies were performed by light and scanning electron microscopy, respectively. Microscopy results were correlated to tensile testing results. The results indicated that, as the amount of ausferrite present in the matrix increases, higher values of strength and lower ductility are obtained. The fracture surfaces of dual phase ADI microstructures with 22.8% of ausferrite in their matrix have regions of quasi-cleavage fracture around last-to-freeze zones, related to the presence of ausferrite in those areas. The specimens with the highest values of ausferrite of 86.8% among the dual phase microstructure have a dominant quasi-cleavage type of fracture.

scholarly journals Mechanical Characterization of Dual Phase Austempered Ductile Iron

2010 ◽  
Vol 50 (2) ◽  
pp. 302-306 ◽  
Author(s):  
Alejandro Basso ◽  
Martín Caldera ◽  
Micro Chapetti ◽  
Jorge Sikora
Keyword(s):  
Ductile Iron ◽  
Mechanical Characterization ◽  
Austempered Ductile Iron ◽  
Dual Phase

scholarly journals Low Temperature Impact Tests in Austempered Ductile Iron and Other Spheroidal Graphite Cast Iron Structures.

2001 ◽  
Vol 41 (4) ◽  
pp. 372-380 ◽  
Author(s):  
P. J. J. Ratto ◽  
A. F. Ansaldi ◽  
V. E. Fierro ◽  
F. R. Agüera ◽  
H. N. Alvarez Villar ◽  
...  
Keyword(s):  
Cast Iron ◽  
Low Temperature ◽  
Ductile Iron ◽  
Austempered Ductile Iron ◽  
Spheroidal Graphite ◽  
Impact Tests ◽  
Spheroidal Graphite Cast Iron ◽  
Graphite Cast Iron ◽  
Temperature Impact

scholarly journals Multiphase Ausformed Austempered Ductile Iron

2017 ◽  
Vol 62 (3) ◽  
pp. 1493-1498 ◽  
Author(s):  
M. Soliman ◽  
H. Palkowski ◽  
A. Nofal
Keyword(s):  
Microstructure Evolution ◽  
Ductile Iron ◽  
Intercritical Annealing ◽  
True Strain ◽  
Austempered Ductile Iron ◽  
Transformation Kinetics ◽  
Compression Properties ◽  
The Matrix ◽  
Microstructure Examination ◽  
Austempering Temperature

AbstractDuctile iron was subjected to a total true strain (φt) of 0.3 either by applying φtin the austenite region or by apportioning it through applying a true strain of 0.2 in the austenite region before quenching to austempering temperature (TA) of 375°C, where a true strain of 0.1 is applied (ausforming). Additionally, two types of matrices were produced in the ductile iron, namely ausferritic and ferritic-ausferritic matrices. The ferrite is introduced to the matrix by intercritical annealing after austenitization. Dilatometric measurements as well as microstructure examination showed a fast ausferrite transformation directly after applying φAand that the introduction of ferrite to the matrix resulted in a remarkable acceleration of the ausferrite formation. The transformation kinetics, microstructure evolution, hardness and compression properties are studied.

scholarly journals Morphology and wear of high chromium and austempered ductile iron balls as grinding media in ball mills

2021 ◽  
Vol 2070 (1) ◽  
pp. 012201
Author(s):  
BRN Murthy ◽  
Ravichandra Rangappa
Keyword(s):  
Ductile Iron ◽  
Research Work ◽  
Milling Process ◽  
Austempered Ductile Iron ◽  
Spheroidal Graphite ◽  
Wear Loss ◽  
Ball Mills ◽  
High Chromium ◽  
Wear Rates ◽  
Grinding Media

Abstract High chromium balls are recognized as better grinding media in terms of wear rates than forged steel balls, which are conventional grinding media in the milling process of iron ore. In this research work, the wear rate of high chromium balls and austempered ductile iron (ADI) balls as crushing media in a ball mill are compared. ADI are prepared by austenitizing the spheroidal graphite (SG) iron balls at 920 °C for one hour, and step austempering heat treatments were given, which includes the first step austenitizing at 300 °C for 15 min, followed by a second step austenitizing at 400 °C for 60 min. The wear rates were estimated when both balls were used separately by maintaining the same machining conditions and when the balls are mixed. The grinding wear conduct of both materials is evaluated for wear loss in wet grinding conditions. The experimental results reveal that the performance of ADI balls is better than high chromium balls when tested separately and mixed. Results also indicate that the wear rates/revolutions will decrease when the operating period increases.

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