scholarly journals Influence of Solidification Conditions on the Microstructure of Laser-Surface-Melted Ductile Cast Iron

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1174 ◽  
Author(s):  
Damian Janicki ◽  
Jacek Górka ◽  
Waldemar Kwaśny ◽  
Wojciech Pakieła ◽  
Krzysztof Matus
Keyword(s):  
Cast Iron ◽  
Martensitic Transformation ◽  
Retained Austenite ◽  
Thermal Conditions ◽  
Alloy System ◽  
Ductile Cast Iron ◽  
Solidification Path ◽  
Laser Surface ◽  
Melted Zone ◽  
Thermal Data

The thermal conditions in the molten pool during the laser surface melting of ductile cast iron EN-GJS-700-2 were estimated by using infrared thermography and thermocouple measurements. The thermal data were then correlated with the microstructure of the melted zone. Additionally, the thermodynamic calculations of a Fe-C-Si alloy system were performed to predict the solidification path of the melted zone. It was found that increasing the cooling rate during solidification of the refined ledeburite eutectic but also suppressed the martensitic transformation. A continuous network of plate-like secondary cementite precipitates and nanometric spherical precipitates of tertiary cementite were observed in regions of primary and eutectic austenite. The solidification of the melted zone terminated with the Liquid → γ-Fe + Fe3C + Fe8Si2C reaction. The hardness of the melted zone was affected by both the fraction of the retained austenite and the morphology of the ledeburite eutectic.

X-Ray Fractographic Study on Fatigue Fracture Surface of Ductile Cast Iron

1993 ◽  
Vol 37 ◽  
pp. 327-334
Author(s):  
Akira Suzuki ◽  
Yoichi Kishi ◽  
Zenjiro Yajima ◽  
Yukio Hirose
Keyword(s):  
Cast Iron ◽  
Fracture Surface ◽  
Fatigue Fracture ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Compact Tension ◽  
Fatigue Tests ◽  
Ductile Cast Iron ◽  
Fatigue Fracture Surface ◽  
X Ray

Austempered ductile cast iron (ADI) has composite microstructures, which are martensite/retained austenite structures. ADI has very large toughness compared to other ductile cast irons. After fracture, the retained austenite near the fracture surface will be transformed to martensite. In the present study, X-ray fractography is applied to fatigue fracture surface of ADI. The fatigue tests were carried out on compact tension (CT) specimens. The volume fraction of retained austenite was quantitatively measured on and beneath fatigue fracture surfaces. The plastic strain on the fracture surface was estimated from measuring the line broadening of X-ray diffraction profiles. The depth of the plastic zone left on fracture surface was evaluated from the distributions of the volume fraction of retained austenite. The results are discussed on the basis of fracture mechanics.

A Study of Austempered Ductile Cast Iron

1984 ◽  
Vol 34 ◽  
Author(s):  
J. D. Verhoeven ◽  
A. El Nagar ◽  
B. El Sarnagawa ◽  
D. P. Cornwell ◽  
F. Laabs
Keyword(s):  
Cast Iron ◽  
Retained Austenite ◽  
Lattice Parameter ◽  
Ductile Cast Iron ◽  
Austenitizing Temperature ◽  
Iron Matrix ◽  
Gamma Iron ◽  
Step Process ◽  
Austempered Ductile Cast Iron

ABSTRACTExperiments were carried out on unalloyed ductile cast iron to evaluate the % retained austenite (%RY) and its lattice parameter as a function of austenitizing time and temperature for austempering temperatures ranging from 270 to 420°C. Results are related to expected carbon levels in the gamma iron matrix at the austenitizing temperature. It is shown that the rate of austenitization can be described as a two step process and experiments demonstrate that 900°C austenitizatlon is complete after 8m. An 1100°C homogenizatdon has been shown to have a small effect upon %RY and rate of austenitization.

High Performance Unalloyed Ductile Cast Iron with Multiphase Structure

2019 ◽  
Vol 295 ◽  
pp. 43-48
Author(s):  
Wen Tao Zhou ◽  
Chen Yang ◽  
Xi Xi Cui ◽  
Zhong Yang Liang ◽  
Xuan Wang ◽  
...  
Keyword(s):  
Cast Iron ◽  
Retained Austenite ◽  
High Performance ◽  
Bainitic Ferrite ◽  
Rapid Quenching ◽  
Ductile Cast Iron ◽  
Fine Needle ◽  
Multiphase Structure ◽  
Matrix Microstructure ◽  
The Matrix

An unalloyed ductile cast iron with a multiphase structure is designed by a novel austempering process. The designed austempering treatment consists of initial rapid quenching to 180°C after austenizing at 890°C for 20min, and finally austempering at 220°C for 240min. A multiphase structure comprising lenticular/needle-like prior martensite, fine needle bainitic ferrite and film retained austenite is obtained. The excellent mechanical properties, with a tensile strength of 1530MPa and an elongation of 3.1% can be achieved by controlling the matrix microstructure of 12% prior martensite, 15% retained austenite with 1.64% carbon content, and 73% bainitic ferrite. This is mainly attributed to prior marteniste which can promote refinement of multiphase colonies.

scholarly journals Microstructural Evolution During Laser Surface Alloying of Ductile Cast Iron with Titanium

2017 ◽  
Vol 62 (4) ◽  
pp. 2425-2431 ◽  
Author(s):  
D. Janicki
Keyword(s):  
Cast Iron ◽  
Solidification Rate ◽  
Titanium Content ◽  
Ductile Cast Iron ◽  
Laser Surface ◽  
Surface Alloying ◽  
Surface Layers ◽  
Composite Surface ◽  
Laser Surface Alloying ◽  
Xrd Diffraction

AbstractDiode laser surface alloying process was used to the in-situ synthesis of TiC-reinforced composite surface layers on the ductile cast iron substrate. The obtained composite surface layers were investigated using optical and scanning electron microscopy, and XRD diffraction.It was found that the morphology and fraction of TiC phase is directly dependent upon both the concentration of titanium in the molten pool and also the solidification rate. With increasing titanium content, the fraction of TiC increases, whereas the fraction of cementite decreases. The TiC phase promotes a heterogeneous nucleation of primary austenite grains, what reduces a tendency of cracking in the alloyed layers.

Effects of CO2 Laser Surface Hardening in the Unlubricated Wear of Ductile Cast Iron Against Alumina

1996 ◽  
Vol 118 (4) ◽  
pp. 748-752 ◽  
Author(s):  
C. Papaphilippou ◽  
M. Vardavoulias ◽  
M. Jeandin
Keyword(s):  
Wear Resistance ◽  
Cast Iron ◽  
Co2 Laser ◽  
Surface Hardening ◽  
Normal Load ◽  
Ductile Cast Iron ◽  
Laser Surface ◽  
Sliding Velocity ◽  
Wear Coefficient ◽  
Laser Surface Hardening

The microstructure of a ferrito-pearlitic ductile cast iron has been modified by CO2 laser surface hardening. Analysis of the laser-processed surfaces showed a dramatic increase in microhardness. Dry sliding wear of laser-treated specimens against an alumina counterbody has been investigated by “ball-on-disk” testing. The evolution of the wear coefficient, as well as metallographic observations, revealed an oxidational wear mechanism. The wear resistance of the laser-treated samples was significantly enhanced. The laser-treated cast iron has a better resistance to abrasion and plastic deformation. The improvement of the wear resistance was due to the fine and homogeneous microstructure produced after laser-treatment. Wear plots showing the evolution of wear coefficient with normal load, sliding velocity, and humidity have been established. The wear of the laser-treated cast iron is not influenced by the variation of operating conditions (normal load, sliding velocity, and relative humidity).

X-Ray Study on the Fatigue Fracture Surface of Austempered Ductile Cast Iron

1991 ◽  
Vol 35 (A) ◽  
pp. 503-510 ◽  
Author(s):  
Yoichi Kishi ◽  
Yukio Hirose ◽  
Zenjiro Yajima ◽  
Keisuke Tanaka
Keyword(s):  
Cast Iron ◽  
Fatigue Fracture ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Compact Tension ◽  
Ductile Cast Iron ◽  
Line Broadening ◽  
X Ray ◽  
Fracture Surfaces ◽  
Austempered Ductile Cast Iron

Austempered ductile cast iron (ADI) lias microstructures that consist of martensite and of retained austenite. ADI has very toughness compared with cast iron heat-treated differently. The retained austenite near fracture surfaces transforms to martensite when fracture occurs.In the present study, X-ray fraetography is applied to fatigue fracture surfaces of ADI. The fatigue tests were carried out on compact tension (CT) specimens. The volume fraction of retained austenite was measured quantitatively and the line broadening of X-ray diffraction profiles was measured on and beneath fatigue fracture surfaces. The depth of the plastic zone left on fracture surfaces was evaluated from line broadening. The results are discussed on the basis of fracture mechanics.

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