Precipitation in maraging and martensitic chromium steels — what can we learn using 3-DAP and EFTEM

Stiller, Krystyna Marta; Andrén, Hans-Olof; Andersson, Marcus

doi:10.1179/174328408x296024

Cited by 12 publications

(10 citation statements)

References 45 publications

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“…The η precipitates are larger than the γ and have a rod-like morphology, while the γ precipitates are approximately spherical. After 40 h, Cr-rich α precipitates have appeared in contact with the Ni-rich phases [12,15]. Furthermore, a phase transformation of the γ -Ni 3 (Ti, Al, Si) phase into G-Ni 16 Ti 6 Si 7 takes place at this stage of the aging process (between 40 and 100 h).…”

Section: Introductionmentioning

confidence: 99%

Multiple Influences of Molybdenum on the Precipitation Process in a Martensitic PH Stainless Steel

Thuvander

Andersson

Stiller

2019

Metals

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Molybdenum has been found to influence the complex precipitation process in a martensitic precipitation hardening stainless steel during aging at 475 °C in several different ways. Three steels with different Mo content (0, 1.2 and 2.3 at.%) were investigated. Studies of the microstructure were performed with atom probe tomography and energy filtered transmission electron microscopy. It is shown that, at the initial stage of aging, a faster nucleation of Cu-rich clusters takes place with increasing Mo content. The Cu-clusters act as precipitation sites for other solute elements and promote the nucleation of Ni-rich phases. During further aging, a higher Mo content in the material instead slows down the growth and coarsening of the Ni-rich phases, because Mo segregates to the interface between precipitate and matrix. Additionally, Mo promotes decomposition of the matrix into α and α′ regions. After longer aging times (>40 h) quasicrystalline Mo-rich R′ phase forms (to a greater extent in the material having the highest Mo content). The observations serve to understand the hardness evolution during aging.

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Section: Introductionmentioning

confidence: 99%

Multiple Influences of Molybdenum on the Precipitation Process in a Martensitic PH Stainless Steel

Thuvander

Andersson

Stiller

2019

Metals

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“…Using atom probe, a dense distribution of small platelike MX particles was observed. [13] Since these particles contain a small volume, it can be understood that a minor loss in MX phase fraction can sweep out many particles. According to thermodynamic equilibrium, the phase fraction of MX at 1173 K (900°C) is nearly 30 pct lower than the tempered state at 973 K (700°C).…”

Section: Discussionmentioning

confidence: 99%

“…The smallest recorded values of VN particles in 9 pct Cr steels are platelike particles around 5 to 15 nm in size, which can be observed by using atom probe techniques. [13] Since they contain such a small volume, it will be assumed that r res,MX is zero. This gives an average MX radius of 15 nm.…”

Section: Predicting Microstructure and Creep Properties Of The Hementioning

confidence: 99%

“…[12] Their fine distribution makes it quite difficult to distinguish the smallest particles using standard transmission electron microscopy, and atom probe techniques should be used. [13] Compared to the M 23 C 6 particles, the MX-like particles are more evenly distributed. [6] These particles are also relatively stable against coarsening at typical creep conditions, with average size increasing a few nanometers during 26,000 hours of exposure at 923 K (650°C).…”

Section: Introductionmentioning

confidence: 99%

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Modeling Creep Strength of Welded 9 to 12 Pct Cr Steels

Magnusson

Sandström

2010

Metall Mater Trans A

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The influence of weld-simulated heat treatments of 9 to 12 pct steels is evaluated by a fundamental model for creep. The heat-affected microstructure is predicted by considering particle coarsening, particle dissolution, and subgrain coarsening. Particle coarsening is predicted for a multicomponent system, showing significant M 23 C 6 coarsening in the bcc matrix. Dissolution simulations of MX and M 23 C 6 are performed by considering a size distribution of particles, indicating that the smallest particles can be dissolved already at relatively low welding temperatures. Recovery in dislocation networks will take place due to the coarser particles. Creep rate modeling is performed based on the heat-affected microstructure, showing strength reduction of weld-simulated material by 12 pct at 1123 K (850°C) and 30 pct at 1173 K (900°C). The main cause of this degradation is believed to be the loss of the smallest carbonitrides.

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“…in an irradiation environment. It has been shown in the past that heat treatments on specialized tool steels (Maraging steels [5]) also lead to the formation of finely dispersed intermetallic precipitates [6,7]. The formation of cascades due to particle irradiation and the formation of a large number of point defects cannot be avoided initially.…”

Section: Introductionmentioning

confidence: 99%

Nanostructured Engineering Alloys for Nuclear Application

et al. 2011

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In advanced nuclear applications, high temperature and a corrosive environment are present in addition to a high dose radiation field causing displacement damage in the material. In recent times it has been shown that Nanostructured Ferritic Alloys (NFA's) such as advanced Oxide Dispersion Strengthened (ODS) steels are suitable for this environment as they tolerate high dose irradiation without significant changes in microstructure or relevant mechanical properties. Ion beam irradiation is a fast and cost effective way to induce radiation damage in materials but has limited penetration depth. Therefore, small scale mechanical testing such as nanoindentation and micro compression testing in combination with FIB based sample preparation for micro structural characterization has to be performed allowing a full assessment of the materials' behavior under radiation environment. In this work two different ODS materials have been irradiated using proton and combined proton and He beams up to 1 dpa at different temperatures. Nanoindentation and LEAP measurements were performed in order to assess the changes in properties of these alloys due to irradiation. The same techniques were applied to intermetallic nanostructured alloys in order to investigate the effectiveness of the metal-intermetallic interface to provide defect sinks for He and radiation damage. It was found that irradiation can cause the formation of intermetallic particles even at room temperature while increasing the material strength significantly. 92

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Precipitation in maraging and martensitic chromium steels — what can we learn using 3-DAP and EFTEM

Cited by 12 publications

References 45 publications

Multiple Influences of Molybdenum on the Precipitation Process in a Martensitic PH Stainless Steel

Multiple Influences of Molybdenum on the Precipitation Process in a Martensitic PH Stainless Steel

Modeling Creep Strength of Welded 9 to 12 Pct Cr Steels

Nanostructured Engineering Alloys for Nuclear Application

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