Published by De Gruyter

Volume 58 Issue 2

February 2021

Issue of Practical Metallography

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Contents
Journal Overview

Publicly Available February 19, 2021

Page range: i-ii

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Publicly Available February 19, 2021

Editorial

Page range: 71-71

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February 19, 2021

Heat Treatment Effect on the Microstructure and the Corrosion Resistance of Manganese-Aluminum Bronzes

P. Linhardt, S. Strobl, J. Böhm, M.V. Biezma, R. Haubner

Page range: 72-82

February 19, 2021

Phase Identification in Multi-Phase Cu-Zn/Cu-Al Alloys with Macroscopic Concentration Gradients

T. Kaaden, M. Rettenmayr, S. Lippmann

Page range: 83-95

Abstract

In order to study concentration invariant phase transitions in Cu-Zn-Al alloys which occur in a very narrow concentration range samples with concentration gradients were produced. Cylinders made of brass and Cu-Al bronze were joined by diffusion bonding and subsequently annealed. The samples exhibit multi-phase regions (α, β, γ 1 , martensite) with changing compositions and very different chemical properties. Standard techniques for the metallographic preparation of Cu alloys usually target specific phases within limited concentration ranges. To evaluate the microstructure, a two-stage chemical etching method using sodium hydroxide solution and subsequent selective colour etching was successfully used to gain an overview of the phases present in different areas along the concentration gradient. For the characterization of martensite, its birefringent optical properties were utilized. In polarized light, details of the martensitic structure are revealed which would otherwise only be accessible by scanning electron methods.

Failure analysis

February 19, 2021

Gamma Prime Solutioning Tests of Alloy 247 Specimens

A. Neidel, B. Fischer, M. Giller

Page range: 96-106

Abstract

Strictly speaking, this contribution is not about a case study in failure analysis. However, the investigation described herein was inspired by a failure case. A heavyduty gas turbine engine used in a power and desalination plant in the Middle East experienced creep damage and cracking in some of its row 4 turbine blades after only some 15,000 operating hours. Microstructural alterations detrimental to the creep strength of the alloy were determined to be the metallurgical root cause of the failure. It was believed that said microstructural alterations were brought about by unusual transient operating conditions in engine service. Heat treatment tests were ordered to verify or disprove this hypothesis. It was established that the peculiar gamma prime morphology found in the failed blades can be produced by very high solutioning temperatures and subsequent rapid cooling. Such conditions in engine service are conceivable if sufficient unburnt fuel enters the turbine and ignites downstream of the combustion chamber (high temperature), and if water used in fuel line purging is injected into the turbine section immediately thereafter (rapid cooling). Solutioning above 1240 °C, followed by a water quench, produced said mono-modal fine γ' morphology.

Picture of the Month

February 19, 2021

Picture of the Month

Page range: 107-107

PM-News

February 19, 2021

PM-News

Page range: 108-111

Meeting Diary

February 19, 2021

Meeting Diary

Page range: 112-115

About this journal

Practical Metallography is a bilingual (German-English) journal that informs you thoroughly on materialographic preparation, imaging and analysis of microstructures. The journal covers the development and improvement of metallographic methods and equipment, possibilities of optical and electron microscopy, spectroscopy, diffraction techniques, non-destructive testing, metallographic investigations of materials, problems of specimens preparation and evaluation including useful laboratory advice and recipes, failure analysis including damage detection and elimination.
All articles are subject to thorough, independent peer review.
Practical Metallography works closely with Deutsche Gesellschaft für Materialkunde e.V. (DGM)

Volume 58 Issue 2

Issue of Practical Metallography

Contents

Editorial

Heat Treatment Effect on the Microstructure and the Corrosion Resistance of Manganese-Aluminum Bronzes

Phase Identification in Multi-Phase Cu-Zn/Cu-Al Alloys with Macroscopic Concentration Gradients

Abstract

Gamma Prime Solutioning Tests of Alloy 247 Specimens

Abstract

Picture of the Month

PM-News

Meeting Diary