HTM Journal of Heat Treatment and Materials

Published by De Gruyter

Volume 69 Issue 2

Issue of HTM Journal of Heat Treatment and Materials

Contents
Journal Overview

Veranstaltungen/Events

December 22, 2014

Veranstaltungen in Zusammenarbeit mit der AWT

Page range: A5-A5

HTM-Praxis

December 22, 2014

Preface

E. J. Mittemeijer, B. Scholtes

Page range: 63-63

December 22, 2014

Residual Stress in the Cementite Phase of Cold Drawn Pearlite*

J. Tacq, M. Kriška, M. Seefeldt

Page range: 64-70

Abstract

Residual stresses in cold drawn, pearlitic steel wire have been measured using synchrotron diffraction. In this paper the cementite residual stress evolution is presented. A saturation of the residual stress could be observed. A simple analytical model is proposed to interpret the observed residual stresses in terms of the strain hardening behaviour of the phases present in the material. From the analytical model it follows that it is not reverse plastic yielding of the ferrite that is of primary importance in residual stress saturation, but the actual strain hardening behaviour. The experimentally observed saturation, followed by a gradual decrease of the residual micro phase stress, could be explained by an exponential strain hardening of the ferrite, while the cementite phase doesn't show significant strain hardening.

December 22, 2014

Residual Stress Analysis of Thick Film Systems by the Incremental Hole-Drilling Method*

E. Held, J. Gibmeier

Page range: 71-79

Abstract

Residual stresses play an important role in coating systems as they determine their properties as well as their life-time behavior. In many industrial applications multi-layer systems are used. This work examines the applicability of the incremental hole drilling method to determine residual stress states in multi-layer coating systems, i.e. in the top-layer, in the interlayer and in the substrate. For this purpose systematic finite element (FE) simulations are carried out. Initially, the interfaces were assumed to be planar and subsequently rough interfaces were considered. The results indicate that thin interlayers with layer thicknesses smaller than 30 μm can be neglected in the evaluation of the measured strain relaxations, since they lead only to a minor stress deviation. In case of larger interlayer thicknesses a case-specific calibration, taking into account the exact build-up of the multilayer system, results in reliable determinations of the residual stress states, in the top-layer, the interlayer and the substrate. Finally the simulation results are applied to a model thick film system consisting of a thermally sprayed Al 2 O 3 -coating on a fine-grained construction steel (S690QL). Its residual stress state is determined experimentally by the incremental hole-drilling method.

December 22, 2014

Stress Build-Up during Multilayer Welding with Novel Martensitic Filler Materials*

A. Kromm, T. Kannengießer

Page range: 80-88

Abstract

Controlling the level of mostly detrimental residual stresses already during the welding process would be highly attractive as time and cost consuming post processing may be prevented. Innovative Low Transformation Temperature (LTT-) filler materials are specially designed for controlling weld residual stresses by means of adjusted martensite formation already during welding. Numerous publications can be found on this issue, but they provide only little insight into the interaction between martensite formation and resulting welding residual stresses. Within this study a component weld test was performed in a special large-scale testing facility. In-situ load analysis revealed that the amount of stress reduction during deposition of the individual weld runs is dependent on the weld volume undergoing phase transformation related to the shrinking volume. The residual stresses found after welding show that the desired residual stress control by using LTT alloys is sensitive to welding boundary conditions (i. e. weld geometry, plate thickness) and to be evaluated separately for varying weld scenarios.

December 22, 2014

Characterization of Residual Stress Evolved in Iron-Based Shape Memory Alloys*

S. Suzuki, E. P. Kwon, S.-I. Tanaka

Page range: 89-96

Abstract

It is considered that complicated residual stresses may occur in shape memory alloys (SMAs) during deformation, as the matrix phase is transformed to martensitic phase during plastic deformation and the martensitic phase is reversely transformed by heating. Since the final shape of SMAs are influenced by residual stresses, it is important to characterize the residual stresses formed in SMAs during plastic deformation and annealing. The X-ray diffraction method was used to characterize the phase transformation and the residual stress formed in an Fe-Mn-Si-Cr SMA in this study. The samples were tensile-deformed to different strains and subsequently annealed. The results showed that a part of γ-phase with the face-centered cubic (fcc) structure was found to be transformed to ∊-phase with the hexagonal close-packed (hcp) structure by room-temperature tensile deformation in the SMA, and the ∊-phase was reversely transformed by subsequent heating. It has been also shown that the compressive stress occurred in the tensile direction of the γ-phase on tensile deformation and unloading. The compressive stress is believed to result from the formation of the ∊-phase during stress-induced martensitic transformation. After the deformed samples were annealed to recover their shapes, the residual stress was considerably released. This is considered to be due to the decrease in the amount of the transformed ∊-phase during annealing. These results indicated that residual stress in the fcc matrix phase is correlated with the shape recovery characteristics of the SMA after martensitic and reverse martensitic transformations.

December 22, 2014

Microstructure and Properties of Pearlitic Steel during Cold Wire Drawing: A Residual Stress Perspective*

M. Kriška, J. Tacq, K. Van Acker, M. Seefeldt

Page range: 97-105

Abstract

The residual stress evolution during cold drawing of pearlitic steel wire was followed over a broad strain range by diffraction techniques. The present work discusses possible links between microstructural changes induced by severe deformation and their “footprints” left in the residual stresses on different – macro, micro and nano – scale levels. Energy dispersive synchrotron diffraction revealed a significant divergence in the grain microstress evolution among differently oriented ferrite grains in the high deformation regime beyond an accumulated true strain of about ∊ t ≥ 2.3. A possible physical reason for the observed divergence is discussed in terms of a distinct microstructure development in this stage of the cold wire drawing.

December 22, 2014

Shot Peening Induced Plastic Deformation in Cast Iron – Influence of Graphite Morphology*

M. Lundberg, R. L. Peng, M. Ahmad, D. Bäckström, T. Vuoristo, S. Johansson

Page range: 106-113

Abstract

Graphite morphology in cast iron strongly affects the mechanical properties such as: Young's modulus, tensile/compressive strength and cyclic mechanical behaviour. In this study, pearlitic compact graphite iron (CGI) and grey cast iron (GI) have been studied in a scanning electron microscope (SEM) before and after shot peening under different conditions. The plastic deformation behaviour of CGI and GI under different shot peening conditions has been analysed using electron backscattering diffraction (EBSD) and electron contrast channelling imaging (ECCI). EBSD and ECCI revealed that plastic deformation around graphite inclusions depends on the size and shape of the graphite. The different response of CGI and GI to shot peening is explained by the different damping properties of the graphite and the matrix capability for plastic deformation. n

December 22, 2014

Heat Treatment Effects of Laser Cladded 12 Ni Maraging Tool Steel with Ni-Co-Mo Alloys*

Zoran Bergant, Janez Grum

Page range: 114-123

Abstract

The aim of the research is to study the effect of a two-stage heat treatment process of two iron based Ni-Co-Mo alloys on microstructure, micro-hardness and residual stress distribution. The laser cladding with multi-jet powder injection was used to deposit different alloys on the 12 % nickel maraging tool steel specimens 1.2799 (SIST EN 10027-2) to study the effect on the material's properties. In Ni-Co-Mo-1 austenite alloy, the precipitation hardening had no effect on hardness even after a prolonged overaging for 16 hours at 720 C. The second alloy Ni-Co-Mo-2 has a chemical composition similar to the maraging steel substrate. After 3 hours of precipitation hardening at 550 C, the alloy hardness increased to the level of base material. The residual stresses were measured using the hole drilling method. The residual stress profiles into the depth show predominantly tensile residual stresses in the Ni-Co-Mo-1 deposit and compressive residual stresses in the Ni-Co-Mo-2 deposit. The results indicate the importance of the chemical composition on microstructure, hardness and residual stresses prior and after heat treatment as well as of the quality of the deposited material on the maraging steel.

About this journal

HTM is a bilingual (German-English) independently assessed and periodical standard publication that provides reports on all aspects of heat treatment and material technology in research and production. By publishing trend-setting contributions to research and practical experience reports, HTM helps in answering scientific questions as well as regarding investment decisions in the industry. All articles are subject to thorough, independent peer review.
HTM is the official organ of AWT – the Association of Heat Treatment and Materials Technology.

Volume 69 Issue 2

Issue of HTM Journal of Heat Treatment and Materials

Veranstaltungen in Zusammenarbeit mit der AWT

HTM-Praxis

Kurzfassungen

Inhalt

Preface

Residual Stress in the Cementite Phase of Cold Drawn Pearlite*

Abstract

Residual Stress Analysis of Thick Film Systems by the Incremental Hole-Drilling Method*

Abstract

Stress Build-Up during Multilayer Welding with Novel Martensitic Filler Materials*

Abstract

Characterization of Residual Stress Evolved in Iron-Based Shape Memory Alloys*

Abstract

Microstructure and Properties of Pearlitic Steel during Cold Wire Drawing: A Residual Stress Perspective*

Abstract

Shot Peening Induced Plastic Deformation in Cast Iron – Influence of Graphite Morphology*

Abstract

Heat Treatment Effects of Laser Cladded 12 Ni Maraging Tool Steel with Ni-Co-Mo Alloys*

Abstract

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Volume 69 Issue 2

Issue of HTM Journal of Heat Treatment and Materials

Veranstaltungen in Zusammenarbeit mit der AWT

HTM-Praxis

Kurzfassungen

Inhalt

Preface

Residual Stress in the Cementite Phase of Cold Drawn Pearlite*

Abstract

Residual Stress Analysis of Thick Film Systems by the Incremental Hole-Drilling Method*

Abstract

Stress Build-Up during Multilayer Welding with Novel Martensitic Filler Materials*

Abstract

Characterization of Residual Stress Evolved in Iron-Based Shape Memory Alloys*

Abstract

Microstructure and Properties of Pearlitic Steel during Cold Wire Drawing: A Residual Stress Perspective*

Abstract

Shot Peening Induced Plastic Deformation in Cast Iron – Influence of Graphite Morphology*

Abstract

Heat Treatment Effects of Laser Cladded 12 Ni Maraging Tool Steel with Ni-Co-Mo Alloys*

Abstract