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Hiroshi Noguchi - One of the best experts on this subject based on the ideXlab platform.

  • Fatigue Resistance of Laminated and Non-laminated TRIP-Maraging Steels: Crack Roughness vs Tensile Strength
    Metallurgical and Materials Transactions A, 2019
    Co-Authors: Zhao Zhang, Motomichi Koyama, Meimei Wang, Cemal Cem Tasan, Hiroshi Noguchi
    Abstract:

    Pre-cold-rolling before annealing in transformation-induced plasticity (TRIP) Maraging steels changes the microstructural morphology from lamellar to granular, increasing the tensile strength. However, fatigue tests of plain specimens at ambient temperature and the stress ratio − 1 show that increased strength does not improve the fatigue strength compared to laminated TRIP-Maraging steel, irrespective of stress amplitude. The disappearance of fatigue crack roughness suppresses the improvement in fatigue resistance with increasing strength.

  • Microstructural mechanisms of fatigue crack non-propagation in TRIP-Maraging steels
    International Journal of Fatigue, 2018
    Co-Authors: Zhao Zhang, Motomichi Koyama, Meimei Wang, Kaneaki Tsuzaki, Cemal Cem Tasan, Hiroshi Noguchi
    Abstract:

    Abstract In contrast to conventional martensitic steels, transformation-induced plasticity (TRIP)-Maraging steels exhibit exceptional high ductility without sacrificing strength and excellent fatigue property owing to the retained austenite/Maraging martensite laminated structure. In this study, TRIP-Maraging steel (Fe-9Mn-3Ni-1.4Al-0.01C, wt.%) with fine grained austenite was used to investigate the mechanism of high cycle fatigue resistance. Our analyses revealed that soft austenite region acts as a preferential crack propagation path, but the plastic deformation during crack opening involves martensitic transformation, resisting subsequent crack growth via transformation-induced local hardening or crack closure. Moreover, crack growth along the laminates and across the block boundary forms a zigzag crack path, which would act as roughness-induced crack closure. The combined effect of these factors plays an important role in resisting fatigue crack growth at high cycle fatigue.

Janez Grum - One of the best experts on this subject based on the ideXlab platform.

  • Fatigue Resistance of Maraging Steel after Laser Peening
    2018
    Co-Authors: Luca Petan, Janez Grum, José Luis Ocaña Moreno, Roman Šturm
    Abstract:

    Maraging steels are characterised by an exceptional combination of mechanical properties making them suitable for the manufacturing of parts used in critical and added value applications in aerospace engineering and the tooling industry. Depending on the service environment, Maraging steel components may be exposed to dynamic mechanical stresses, corrosion or stress corrosion cracking, and thermal fatigue. In order for these components to withstand demanding working requirements, further improvements of their mechanical properties are necessary. Researchers have studied several surface engineering techniques on Maraging steels, such as laser surface melting, physical vapour deposition, nitriding, and shot peening. Thus far, the effects of laser peening on Maraging steels have been investigated only through surface layer analysis without conducting fatigue tests which offer further insight into the extent of possible fatigue resistance improvement. The scope of the presented research was to investigate the influence of laser peening on the fatigue resistance of high-strength Maraging steel. The laser process was conducted in confined mode without an absorbent coating using a Q-switched Nd:YAG laser with a constant laser pulse energy. The residual stress analysis showed a significant influence of the chosen laser parameters on the residual stress distribution in the thin surface layer. Consequently, this phenomenon proved to have a huge impact on the fatigue resistance of the analyzed Maraging steel.

  • Effects of Laser Shock Peening on the Surface Integrity of 18 % Ni Maraging Steel
    Strojniski Vestnik-journal of Mechanical Engineering, 2016
    Co-Authors: Luca Petan, José Luis Ocaña, Janez Grum
    Abstract:

    Maraging steels represent a special group of steels where ultrahigh strength is achieved with precipitation hardening. Because of their superior mechanical properties, Maraging steels are used for the manufacturing of parts in the aerospace and tooling industry. Usually these mechanical components operate in demanding environments and conditions where they are subject to mechanical fatigue, thermomechanical fatigue, corrosion, and wear. The scope of the research presented in this paper is to analyze the effects of laser shock peening (LSP) on surface integrity characteristics of X2NiCoMo18-9-5 Maraging steel. In this study, Maraging steel specimens, in both quenched and aged condition, were treated with LSP by varying the pulse density. The effects of laser treatment on surface integrity were analyzed with roughness, residual stress, and microhardness measurements. According to the measurement results, LSP generated high compressive residual stresses in the steel surface layer with relatively low surface roughness, which indicates possible fatigue resistance improvements in 18 % Ni Maraging steel.

  • Nanoscale evaluation of laser-based surface treated 12Ni Maraging steel
    Applied Surface Science, 2005
    Co-Authors: Janez Grum, Janez Marko Slabe
    Abstract:

    Maraging steels are used in several high-tech areas. Among them are highly thermo-mechanically loaded vital parts of die casting dies for pressure die casting of aluminium and magnesium alloys. From the economic point of view, the operation life of dies is extremely important to the price of the castings. Operational life can be successfully extended by a regular maintenance of die parts. Laser surfacing is a very promising process for rebuilding of worn out surfaces of vital die parts. In this research, the state in the Maraging steel 1.2799 (DIN) after the application of laser surfacing process has been analysed using scanning electron microscope. The analysis revealed diverse microstructure through-depth of the laser-surfaced specimens. On the basis of the estimated size and volume fraction of the nano-precipitates in the individual microstructure zones located through-depth of the heat-affected zone, a through-depth variation of microhardness was predicted. The results are supported by Vickers microhardness tests. It was confirmed that the mechanical properties of the 1.2799 Maraging steel strongly depend on the characteristic at the nano or micro level. Some of the results obtained can be also applied to laser surface heat treatment of Maraging steels.

  • MAGNETIC MICRO-PROBE DETERMINATION OF THE CONDITION OF Maraging STEEL
    2005
    Co-Authors: Matevž Zupancic, Janez Grum
    Abstract:

    Microstructural and mechanical properties of precipitation-hardened Maraging steel could be stated on a basis of magnetic properties of such a material. A correlation between mechanical and magnetic properties of the Maraging steel is treated from the view of non-destructive testing during and after heat treatment as well as during use under unfavourable conditions at elevated operating temperatures. A group of Maraging steels shows numerous technical and technological properties, which substantially differ from those of classical steels, i.e. excellent weldability, high ductility in soft state, high hardening ability and favourable suitability for EDM machining. All of those properties are extremely important in machining of technologically exacting products such as die casting dies. The selected Maraging steel contains 12 % of nickel and is primarily intended for the production of hot-working dies and various machine elements exposed to heavy mechanical and thermo-mechanical loads. Non-destructive testing of Maraging steels enables cheaper and more reliable production. Selected characteristic properties for testing of Maraging steel after precipitation hardening are impact toughness, hardness, and residual magnetism. Supervision should be performed not only during precipitation hardening but also during the use of such a material at elevated temperatures at which additional precipitation may occur, which could lead to overaging of the micro-structure. A fast and reliable method of non-destructive testing of mechanical properties could significantly affect the time, price and quality of production as well as maintenance of products made of Maraging steel.

Zhao Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Fatigue Resistance of Laminated and Non-laminated TRIP-Maraging Steels: Crack Roughness vs Tensile Strength
    Metallurgical and Materials Transactions A, 2019
    Co-Authors: Zhao Zhang, Motomichi Koyama, Meimei Wang, Cemal Cem Tasan, Hiroshi Noguchi
    Abstract:

    Pre-cold-rolling before annealing in transformation-induced plasticity (TRIP) Maraging steels changes the microstructural morphology from lamellar to granular, increasing the tensile strength. However, fatigue tests of plain specimens at ambient temperature and the stress ratio − 1 show that increased strength does not improve the fatigue strength compared to laminated TRIP-Maraging steel, irrespective of stress amplitude. The disappearance of fatigue crack roughness suppresses the improvement in fatigue resistance with increasing strength.

  • Microstructural mechanisms of fatigue crack non-propagation in TRIP-Maraging steels
    International Journal of Fatigue, 2018
    Co-Authors: Zhao Zhang, Motomichi Koyama, Meimei Wang, Kaneaki Tsuzaki, Cemal Cem Tasan, Hiroshi Noguchi
    Abstract:

    Abstract In contrast to conventional martensitic steels, transformation-induced plasticity (TRIP)-Maraging steels exhibit exceptional high ductility without sacrificing strength and excellent fatigue property owing to the retained austenite/Maraging martensite laminated structure. In this study, TRIP-Maraging steel (Fe-9Mn-3Ni-1.4Al-0.01C, wt.%) with fine grained austenite was used to investigate the mechanism of high cycle fatigue resistance. Our analyses revealed that soft austenite region acts as a preferential crack propagation path, but the plastic deformation during crack opening involves martensitic transformation, resisting subsequent crack growth via transformation-induced local hardening or crack closure. Moreover, crack growth along the laminates and across the block boundary forms a zigzag crack path, which would act as roughness-induced crack closure. The combined effect of these factors plays an important role in resisting fatigue crack growth at high cycle fatigue.

Venkata P Ramana - One of the best experts on this subject based on the ideXlab platform.

  • role of nickel as an interlayer in dissimilar metal friction welding of Maraging steel to low alloy steel
    Journal of Materials Processing Technology, 2012
    Co-Authors: Madhusudhan G Reddy, Venkata P Ramana
    Abstract:

    Abstract Continuous drive friction welding of dissimilar metals, Maraging steel and low alloy steel was carried out. It was observed that the hardness, ductility and impact toughness of Maraging steel are low due to the diffusion of elements such as carbon, manganese, silicon and phosphorus from low alloy steel to Maraging steel. An attempt was made in this study to improve the properties by friction welding of Maraging steel and low alloy steel with nickel as an interlayer. The hardness, tensile strength and impact toughness are observed to be improved, as nickel acted as diffusion barrier. The effect of post-weld heat treatments on microstructure and mechanical properties of dissimilar metal friction welds with and without interlayer was also studied. Maraging steel responded to solutionizing & aging and low alloy steel responded to quenching and tempering. The notch tensile strength and impact toughness in case of dissimilar metal weld with interlayer are observed to be more than that of the dissimilar metal weld without interlayer.

  • microstructure and residual stress distribution of similar and dissimilar electron beam welds Maraging steel to medium alloy medium carbon steel
    Materials & Design, 2010
    Co-Authors: Venkata P Ramana, T Mohandas, Madhusudha G Reddy, A V S S K S Gupta
    Abstract:

    The influence of parent metal heat treatment condition on the residual stress distribution in dissimilar metal welds of Maraging steel to quenched and tempered medium alloy medium carbon steel has been investigated. It has been observed that the residual stress distribution would be more compressive if the Maraging steel is in soft condition. This is attributed to stress absorbing nature of highly yielding soft Maraging steel.

A V S S K S Gupta - One of the best experts on this subject based on the ideXlab platform.