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1

Revealing Prior-Austenite Grain Boundaries and Martensitic Structure of As-Quenched AISI 4140 Steel Treated by Plasma Electrolysis

100%

Cenk Kumruoglu L., Özel A.

Acta Physica Polonica A

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2013

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vol. 123

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issue 2

404-406

EN

The determination of prior-austenite grain size has been the subject of metallurgical research efforts for many years. Metallurgical laboratories are often required to perform prior-austenite grain size determinations on martensitic steel components that have been heat treated. Although these methods may occasionally be mandated by material or procedural specifications, they are typically not preferred because they have a tendency of altering the as-received microstructure. These processes can also be labour-intensive and costly. The goal of this work is to chemically etch and identify the prior austenite grain size and martensitic structure of AISI 4140 steel treated by plasma electrolysis. Polished samples were immersed in 60% HCl, 30% HNO_3, 5% HF, 5% H_2O for 5 seconds then immersed in 5% picric acid, 5% HCl, 90% ethanol to reveal microstructures. Finally, the grain boundary and lath martensitic structure were revealed.

2

Wear Performance of Hardened 1.2333 Cold Work Tool Steel by Plasma Electrolysis

100%

Özel A., Kumruoglu L.

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vol. 125

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issue 2

304-306

EN

Plasma electrolysis is an electrolytic-chemical-thermal technique that can be used for local hardening of the different type of steels. The feasibility of hardening the 1.2333 cold work tool steel by applying a single-stage-local surface treatment, which combines the methods of plasma electrolysis, is discussed. The effects of treatment durations of plasma electrolytic hardening on the surface microstructural, mechanical, and tribological characteristics of 1.2333 cold work steel substrates are studied. The major advantage of the plasma electrolytic hardening is shown to be hardened layer (maximum 900 Hv - minimum 500 Hv) of the substrates consisting of martensitic phase in very short treatment durations, approximately 7 mm thick/0.5 min. Reciprocating-sliding friction and wear tests against an alumina ball counter face have shown that the application of a plasma electrolysis promotes a change in wear mechanism of the friction pair from relatively severe adhesion-abrasion to mild deformation. This results in simultaneous reduction of the volumetric wear rate from 0.18-0.2 mm^3 to 0.04 mm^3.

3

The Evolution of Microstructure for Ductile Iron Treated under Different Thermal Cycles Using Electrolytic Plasma Treatment

88%

Ayday A., Durman M.

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vol. 125

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issue 2

577-578

EN

The effects of the thermal cycles on the microstructures and properties of ductile iron modified by electrolytic plasma treatment were investigated. Microstructure changes occurring in the modified surface were characterized with scanning electron microscopy, X-ray diffractometry techniques. Martensitic structure evolved in the heat affected zone and ledeburite structure was produced in the molten zone of the ductile iron. Microhardness of the treated specimens improved considerably as compared to the original sample. X-ray diffraction clearly revealed the formation of a martensite phases in the modified zone.

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3 Acta Physica Polonica A

2 2014

1 2013

2 Özel A.

1 Ayday A.

1 Cenk Kumruoglu L.

1 Durman M.

1 Kumruoglu L.

Revealing Prior-Austenite Grain Boundaries and Martensitic Structure of As-Quenched AISI 4140 Steel Treated by Plasma Electrolysis

Wear Performance of Hardened 1.2333 Cold Work Tool Steel by Plasma Electrolysis

The Evolution of Microstructure for Ductile Iron Treated under Different Thermal Cycles Using Electrolytic Plasma Treatment