scholarly journals Phase Transition Kinetics in Austempered Ductile Iron (ADI) with Regard to Mo Content

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5266
Author(s):  
Martin Landesberger ◽  
Robert Koos ◽  
Michael Hofmann ◽  
Xiaohu Li ◽  
Torben Boll ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Neutron Diffraction ◽  
Ductile Iron ◽  
Retained Austenite ◽  
Length Change ◽  
Atom Probe ◽  
Carbon Accumulation ◽  
Austempered Ductile Iron ◽  
Mo Content

The phase transformation to ausferrite during austempered ductile iron (ADI) heat treatment can be significantly influenced by the alloying element Mo. Utilizing neutron diffraction, the phase transformation from austenite to ausferrite was monitored in-situ during the heat treatment. In addition to the phase volume fractions, the carbon enrichment of retained austenite was investigated. The results from neutron diffraction were compared to the macroscopic length change from dilatometer measurements. They show that the dilatometer data are only of limited use for the investigation of ausferrite formation. However, they allow deriving the time of maximum carbon accumulation in the retained austenite. In addition, the transformation of austenite during ausferritization was investigated using metallographic methods. Finally, the distribution of the alloying elements in the vicinity of the austenite/ferrite interface zone was shown by atom probe tomography (APT) measurements. C and Mn were enriched within the interface, while Si concentration was reduced. The Mo concentration in ferrite, interface and austentite stayed at the same level. The delay of austenite decay during Stage II reaction caused by Mo was studied in detail at 400 °C for the initial material as well as for 0.25 mass % and 0.50 mass % Mo additions.

Recent Advances in Machining of Austempered Ductile Iron to Avoid Machining Induced Microstructural Phase Transformation Reaction

2014 ◽  
Author(s):  
Ashwin Polishetty ◽  
Guy Littlefair
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Plastic Strain ◽  
Phase Transformations ◽  
Thermal Energy ◽  
Ductile Iron ◽  
Ductile Cast Iron ◽  
Austempered Ductile Iron ◽  
Depth Of Cut ◽  
Mathematical Function

Austempered Ductile Iron (ADI) is a type of nodular, ductile cast iron subjected to heat treatments — austenitising and austempering. Whilst machining is conducted prior to heat treatment and offers no significant difficulty, machining post heat treatment is demanding and often avoided. Phase transformation of retained austenite to martensite leading to poor machinability characteristics is a common problem experienced during machining. Study of phase transformations is an investigative study on the factors — plastic strain (εp) and thermal energy (Q) which effect phase transformations during machining. The experimental design consists of face milling grade 1200 at variable Depth of Cut (DoC) range from 1 to 4 mm, coolant on/off, at constant speed, 1992 rpm and feed rate, 0.1 mm/tooth. Plastic strain (εp) and martensite content (M) at fracture point for each grade was evaluated by tensile testing. The effect of thermal energy (Q) on phase transformations was also verified through temperature measurements at DoC 3 and 1 mm using thermocouples embedded into the workpiece. Finally, the amount of plastic strain (εp) and thermal energy (Q) responsible for a given martensite increase (M) during milling was related and calculated using a mathematical function, M = f (εp, Q). The future work of the thesis involves an in-depth study on the new link discovered through this research: mathematical model relating the role of plastic strain and thermal energy in martensite formation.

Microstructure Evolution during Strain-Induced Transformation of Austenite in an Austempered Ductile Iron (ADI)

2021 ◽  
Vol 1016 ◽  
pp. 1199-1204
Author(s):  
R. Raghavendran ◽  
Anil Meena ◽  
Murugaiyan Amirthalingam
Keyword(s):  
Phase Transformation ◽  
Thermomechanical Treatment ◽  
Ductile Iron ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Thermomechanical Processing ◽  
Base Material ◽  
High Volume ◽  
Austempered Ductile Iron ◽  
Conventional Heat Treatment

Microstructural evolution during the strain-induced phase transformation of austenite in an Austempered ductile iron (ADI) under various thermomechanical processing conditions is studied in the present study. An alloyed ductile iron is taken as the base material, and thermomechanical treatment is carried out on a Gleeble 3800 thermomechanical simulator coupled with dilatometry. The effect of deformation on the austempering process has been studied by microstructure characterization using optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. The variations in retained austenite volume fraction and its carbon content with respect to different austempering times are analyzed to study the effect of strain-induced transformation of austenite. It has been observed that the thermomechanical treatment significantly influences the phase transformation kinetics during the austempering process. The thermomechanical treatment produced a martensite free ausferritic microstructure for all austempering times with a high volume fraction of carbon enriched retained austenite as compared to the conventional heat treatment.

The Application of Analysis of Variance to Phase Transformation of an Austempered Ductile Iron

2015 ◽  
Vol 1128 ◽  
pp. 338-343
Author(s):  
Flavius Aurelian Sarbu ◽  
Ioan Milosan
Keyword(s):  
Phase Transformation ◽  
Analysis Of Variance ◽  
Ductile Iron ◽  
Repeated Measures ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Austempered Ductile Iron ◽  
The One

The paper presents an example of calculation for the one-way repeated measures applied for the results of an austempered ductile iron. This research has a number of objectives which can be started as follows: 1. to determine of the volume fraction of retained austenite (Vγr); 2. the calculation for the one-way repeated measures applied for the results of the volume fraction of retained austenite (Vγr).

scholarly journals INFLUENCE OF AUSTEMPERING TIME AND AUSTEMPERING TEMPERATURE IN MICROSTRUCTURE AND MECHANICAL PROPERTIES IN AUSTEMPERED DUCTILE IRON

2020 ◽  
Vol 8 (6) ◽  
pp. 51-62
Author(s):  
Giulliana Victória Tissi ◽  
Gláucio Soares Da Fonseca
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Ductile Iron ◽  
Retained Austenite ◽  
Microstructural Analysis ◽  
Austempered Ductile Iron ◽  
Microstructure And Mechanical Properties ◽  
Different Temperatures ◽  
Austempering Temperature ◽  
Microscopic Techniques

Austempered Ductile Iron (ADI) has excellent mechanical properties related to its microstructure ausferrite, and with the cycle of austempering heat treatment, many mechanical properties can be obtained from the same alloy, simply changing the time and temperature. To evaluate the influence of austempering time and temperature on the ADI, analyzed the modifications in the microstructures and mechanical properties of the samples of ductile iron, subjected to austempering heat treatment with austenitizing time and temperature of 910 °C and 90 minutes and during the austempering bath, the samples were submitted to different temperatures, 300, 320, 340, 360 e 380 °C, and for four different times for each temperature, 75, 110, 145 and 180 minutes. For the microstructural analysis, the microscopic techniques were used: optical and scanning electron and mechanical properties were obtained by mechanical testing of hardness and impact. The results show that there is a relationship between austempering temperature with microstructure and mechanical properties. The highest retained austenite and energy absorbed were 25.73% and 130 J, respectively, for the austempered sample at 380 °C and 180 minutes and the highest hardness value was 458 HB for the austempered sample at 300 °C and 75 minutes.  

scholarly journals The Selection of Heat Treatment Parameters to Obtain Austempered Ductile Iron with the Required Impact Strength

2018 ◽  
Vol 27 (11) ◽  
pp. 5865-5878 ◽  
Author(s):  
Dorota Wilk-Kołodziejczyk ◽  
Krzysztof Regulski ◽  
Tomasz Giętka ◽  
Grzegorz Gumienny ◽  
Krzysztof Jaśkowiec ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Impact Strength ◽  
Ductile Iron ◽  
Austempered Ductile Iron ◽  
Selection Of

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.

scholarly journals Austenitization of FerriticDuctile Iron

2014 ◽  
Vol 14 (4) ◽  
pp. 49-54 ◽  
Author(s):  
A. Krzyńska ◽  
A. Kochański
Keyword(s):  
Heat Treatment ◽  
Ductile Iron ◽  
Starting Material ◽  
Austempered Ductile Iron ◽  
Isothermal Quenching ◽  
Micro Hardness ◽  
Hardness Testing ◽  
Ferritic Matrix ◽  
Rate Of Dissolution ◽  
Nodular Graphite

Abstract Austenitization is the first step of heat treatment preceding the isothermal quenching of ductile iron in austempered ductile iron (ADI) manufacturing. Usually, the starting material for the ADI production is ductile iron with more convenient pearlitic matrix. In this paper we present the results of research concerning the austenitizing of ductile iron with ferritic matrix, where all carbon dissolved in austenite must come from graphite nodules. The scope of research includedcarrying out the process of austenitization at 900° Cusing a variable times ranging from 5 to 240minutes,and then observations of the microstructure of the samples after different austenitizing times. These were supplemented with micro-hardness testing. The research showed that the process of saturating austenite with carbon is limited by the rate of dissolution of carbon from nodular graphite precipitates

Advances in Carbidic Austempered Ductile Iron (CADI) – a wear resistant material

2021 ◽  
Vol 14 ◽  
Author(s):  
Lakshmiprasad Maddi ◽  
Ajay Likhite
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Cast Iron ◽  
Ductile Iron ◽  
Viable Alternative ◽  
Austempered Ductile Iron ◽  
Resistant Material ◽  
Fine Carbide ◽  
Matrix Graphite ◽  
Malleable Cast

Background: Ductile irons provide a more viable alternative for malleable cast iron in areas that do not demand extreme wear resistance. Austempering of ductile irons was a well researched area in the last two decades. Attempts to further improve the wear resistance led to the development of Carbidic austempered ductile iron (CADI), wherein the carbides contribute to wear resistance. Combination of ausferritic matrix, graphite nodules, and carbides (eutectic and alloy) symbolizes the microstructure of CADI. Methods: Two principal approaches adopted by the researchers to change the microstructure are (i) addition of carbide forming elements (ii) heat treatment (s). Results: Both the above methods result in the refinement of graphite nodules, carbide precipitations, along with fine ausferrite. Conclusion: Improvement in hardness, toughness and wear resistance was observed largely as a consequence of fine carbide precipitations and formation of martensite.

Characteristics of the Transformation of Retained Austenite in Tempered Austempered Ductile Iron

2017 ◽  
Vol 26 (5) ◽  
pp. 2095-2101 ◽  
Author(s):  
Bingxu Wang ◽  
Gary Barber ◽  
Xichen Sun ◽  
Michael Shaw ◽  
Phil Seaton
Keyword(s):  
Ductile Iron ◽  
Retained Austenite ◽  
Austempered Ductile Iron
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