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.

A Case Study on Effect of Feed Rate on Machinability of Austempered Ductile Iron

2013 ◽  
Vol 748 ◽  
pp. 247-251 ◽  
Author(s):  
Ashwin Polishetty ◽  
Guy Littlefair ◽  
Timotius Pasang
Keyword(s):  
Heat Treatment ◽  
Ductile Iron ◽  
Feed Rate ◽  
Ductile Cast Iron ◽  
Austempered Ductile Iron ◽  
Depth Of Cut ◽  
X Ray Diffraction ◽  
Tool Failure ◽  
Before And After

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. This case study explains the effect of feed rate on machinability of ADI using cutting force analysis and tool failure analysis. The experimental design consists of conducting drilling trials on grade 1200 and 1400 at constant depth of cut, 25mm; constant speed, 45m/min; no coolant and variable feed rates from 0.2 to 0.35 mm/rev (increment of 0.025mm/rev). Metallography and X-ray diffraction technique was carried out in order to identify and quantify the microstructural phases before and after drilling. The results from the trial infer that the best way to machine ADI efficiently without tool failure is using low feeds and high speeds and without coolant.

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.

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.

The impact of cutting speed and depth of cut on cutting force during turning of austempered ductile iron

2019 ◽  
Vol 19 ◽  
pp. 663-669
Author(s):  
Prashant Parhad ◽  
Vinayak Dakre ◽  
Ajay Likhite ◽  
Jatin Bhatt
Keyword(s):  
Cutting Force ◽  
Ductile Iron ◽  
Cutting Speed ◽  
Austempered Ductile Iron ◽  
Depth Of Cut ◽  
The Impact

Turning of Austempered Ductile Iron with ceramic tools

2020 ◽  
pp. 095440542095715 ◽  
Author(s):  
A Fernández-Valdivielso ◽  
LN López de Lacalle ◽  
P Fernández-Lucio ◽  
H González
Keyword(s):  
Heat Treatment ◽  
Tool Wear ◽  
Ductile Iron ◽  
High Strength ◽  
Cutting Parameters ◽  
Precise Determination ◽  
Machining Process ◽  
Austempered Ductile Iron ◽  
Machining Time ◽  
Ceramic Tools

Austempered ductile iron castings (ADI) are characterized by the high strength and resistance to fatigue, impact, and wear. ADI mechanical properties are obtained by performing a heat treatment on ductile iron casting. Thus, the so-called ausferrite microstructure is achieved. However, heat treatment significantly affects ductile casting machinability. A precise determination of ADI microstructure, on the one hand, and to choose correct machining process parameters and tool wear control on the other, are essential to optimize cutting processes and for the introduction of ceramic inserts. Ceramics are an alternative to carbide tools. In this paper, ceramic tools for the dry turning of ADI castings are studied. Thus, different technical ceramics were analyzed, identifying the dominant wear mechanism and evolution. Tool wear rate magnitude was determined indirectly by the variation of cutting force along machining time. Finally, different tests helped to study ceramics wear sensitivity with respect to cutting parameters. Mixed ceramics of Al2O3 with TiC showed the best performance, followed by SiAlON ones.

The Influence of Boron on Structure and Mechanical Properties of Bainite Ductile Iron in the Step Austempering in Room Temperature Machine Oil

2010 ◽  
Vol 139-141 ◽  
pp. 235-238
Author(s):  
De Qiang Wei
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cast Iron ◽  
Impact Strength ◽  
Ductile Iron ◽  
Room Temperature ◽  
Solute Drag ◽  
Ductile Cast Iron ◽  
Treatment Technique ◽  
The Impact

In this paper, the low alloy bainite ductile cast iron has been obtained by a new heat treatment technique of the step austempering in room-temperature machine oil. The effects of element boron, manganese and copper on structure and mechanical properties of the bainite ductile cast Iron in above-mentioned process are investigated. The phenomenon, hardness lag of the alloyed bainite ductile cast Iron, has been discussed. It shows that after the step austempering in room-temperature machine oil, the hardness will increases with the time. It is found that boron and manganese can increase the hardness and reduce the impact strength while copper can increase the impact strength. The results show that reasonable alloyed elements can improve mechanical properties of the bainite ductile cast Iron. Essentially, hardness lag of the alloyed bainite ductile cast Iron is resulted from solute drag-like effect.

scholarly journals Твердофазные реакции и фазовые превращения в наноразмерной пленочной структуре висмут/селен

2018 ◽  
Vol 52 (8) ◽  
pp. 823
Author(s):  
В.Я. Когай ◽  
Г.М. Михеев
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Phase Transformations ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Film Structure ◽  
Phase Synthesis ◽  
Crystallite Sizes ◽  
Solid Phase Reactions ◽  
First Time

AbstractExperimental results of a study concerned with solid-phase reactions and phase transformations in a Bi/Se nanoscale film structure under heat treatment in vacuum are presented. Nanocrystalline Bi2Se3, BiSe, and Bi_4Se_3 films are obtained for the first time by solid-phase synthesis at various ratios between the Bi and Se layer thicknesses. The phase-transformation temperatures at which Se, BiSe, and Bi4Se3 crystalline phases are formed are determined. The average crystallite sizes in the Bi_2Se_3, BiSe, and Bi_4Se_3 films are found to be 21, 23, and 33 nm, respectively.

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