scholarly journals Strain-Ageing of Low-Alloyed Multiphase High-Strength Steels

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 439 ◽  
Author(s):  
Ludovic Samek ◽  
Jakub Dykas ◽  
Emmanuel De Moor ◽  
Adam Grajcar
Keyword(s):  
Strain Aging ◽  
Volume Fraction ◽  
High Strength Steels ◽  
High Strength ◽  
X Ray Diffraction ◽  
X Ray ◽  
Static Strain ◽  
Static Strain Aging ◽  
Thin Foils ◽  
Long Time

The strain-aging of low alloyed, multiphase high-strength steels with strain-induced austenite to martensite transformation was studied. The influence of prestrain, aging time, and temperature dependence of the static strain aging was carried out. Ageing temperatures between 60 and 220 ∘ C and aging times from 20 to 10,000 min were investigated. The choice of steel composition allowed studying the influence of alloying elements, such as Si and Al, on the static strain aging behavior. Samples after aging were studied using light-optical microscopy, X-ray diffraction, and in-depth transmission electron microscopy (TEM). The Harper model was used to describe the precipitation mechanisms occurring during aging. The study of thin foils after aging using TEM showed the precipitation of low temperature transition carbides in the microstructure, which was observed between 60 and 5000 min. By using X-ray diffraction, it was revealed that aging at 170 ∘ C for a long time caused a slight decrease of the retained austenite volume fraction, but the C content remained constant.

scholarly journals Characterising the Microstructure of an Additively Built Al-Cu-Li Alloy

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5188
Author(s):  
Iris Raffeis ◽  
Frank Adjei-Kyeremeh ◽  
Uwe Vroomen ◽  
Silvia Richter ◽  
Andreas Bührig-Polaczek
Keyword(s):  
Volume Fraction ◽  
Analytical Techniques ◽  
High Strength ◽  
High Energy ◽  
Phase System ◽  
X Ray Diffraction ◽  
Powder Bed ◽  
X Ray ◽  
Conventional View ◽  
Multi Phase

Al-Cu-Li alloys are famous for their high strength, ductility and weight-saving properties, and have for many years been the aerospace alloy of choice. Depending on the alloy composition, this multi-phase system may give rise to several phases, including the major strengthening T1 (Al2CuLi) phase. Microstructure investigations have extensively been reported for conventionally processed alloys with little focus on their Additive Manufacturing (AM) characterised microstructures. In this work, the Laser Powder Bed Fusion (LPBF) built microstructures of an AA2099 Al-Cu-Li alloy are characterised in the as-built (no preheating) and preheat-treated (320 °C, 500 °C) conditions using various analytical techniques, including Synchrotron High-Energy X-ray Diffraction (S-HEXRD). The observed dislocations in the AM as-built condition with no detected T1 precipitates confirm the conventional view of the difficulty of T1 to nucleate on dislocations without appropriate heat treatments. Two main phases, T1 (Al2CuLi) and TB (Al7.5Cu4Li), were detected using S-HEXRD at both preheat-treated temperatures. Higher volume fraction of T1 measured in the 500 °C (75.2 HV0.1) sample resulted in a higher microhardness compared to the 320 °C (58.7 HV0.1) sample. Higher TB volume fraction measured in the 320 °C sample had a minimal strength effect.

X-Ray Residual Stress Measurement on Stress Corrosion Fracture Surfaces

1992 ◽  
Vol 36 ◽  
pp. 543-549
Author(s):  
Masaaki Tsuda ◽  
Yukio Hirose ◽  
Zenjiro Yajima ◽  
Keisuke Tanaka
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Fracture Surface ◽  
Stress Corrosion ◽  
Stress Measurement ◽  
High Strength Steels ◽  
High Strength ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fracture Surfaces

X-ray fractography is a new method utilizing the X-ray diffraction technique to observe the fracture surface for the analysis of the micromechanisms and mechanics of fracture. X-ray residual stress has been confirmed to be a particularly useful parameter when studying the fracture surfaces of high strength steels. The method has been applied to the fracture surface of fracture toughness and fatigue specimens.

X-ray Residual Stress Measurement on Fracture Surface of Stress Corrosion Cracking

1989 ◽  
Vol 33 ◽  
pp. 327-334 ◽  
Author(s):  
Masaaki Tsuda ◽  
Yukic Hirose ◽  
Zenjiro Yajima ◽  
Keisuke Tanaka
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Fracture Surface ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Stress Measurement ◽  
High Strength Steels ◽  
High Strength ◽  
X Ray Diffraction ◽  
X Ray

X-ray fractography is a new method utilizing the X-ray diffraction technique to observe the fracture surface for the analysis of the micromechanisms and mechanics of fracture. The X-ray residual stress has been confirmed to be a particularly useful parameter when studying the fracture surfaces of high strength steels. The method has been applied to the fracture surface of fracture toughness and fatigue specimens.

scholarly journals The Effect of Mn and Si on the Properties of Advanced High Strength Steels Processed by Quenching and Partitioning

2010 ◽  
Vol 654-656 ◽  
pp. 94-97 ◽  
Author(s):  
Bohuslav Mašek ◽  
Hana Jirková ◽  
Daniela Hauserova ◽  
Ludmila Kučerová ◽  
Danuše Klauberová
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength Steels ◽  
High Strength ◽  
Microstructural Development ◽  
X Ray Diffraction ◽  
Quenching And Partitioning ◽  
Advanced High Strength Steels ◽  
High Ultimate Strength

The concepts new types of materials are, for economic reasons, focused mainly on low alloyed steels with a good combination of strength and ductility. Suitable heat and thermo-mechanical treatments play an important role for the utilization of these materials. Different alloying strategies are used to influence phase transformations. The quenching and partitioning process (Q-P Process) is one of the heat treatment methods which can result in a high ultimate strength as well as a good ductility. However, these good properties can be obtained only if a sufficient amount of retained austenite is stabilized. The influence of different contents of manganese, silicon and chromium on microstructural development and mechanical properties were experimentally tested. Alloying elements were used to stabilize the retained austenite in the final microstructure and also to strengthen the solid solution. Ultimate strengths of over 2000MPa with ductility over 10% were reached after the optimization of the Q-P Process. The microstructures were analyzed using several microscopic methods; mechanical properties were determined by a tensile test and the volume fraction of the retained austenite was established by X-ray diffraction phase analysis.

scholarly journals Study on Static Strain Aging Kinetics of High-Carbon Steel Wires and Its Impact on High-Strength Steel Cords

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1684
Author(s):  
Tamás Bálint Mező ◽  
Péter Barkóczy
Keyword(s):  
Carbon Steel ◽  
Strain Aging ◽  
High Carbon Steel ◽  
High Strength ◽  
Aging Effect ◽  
Static Strain ◽  
Static Strain Aging ◽  
Steel Wires ◽  
Steel Cords ◽  
Kinetics Of

Under quasi-static loading, an irregular failure mode of high-strength thin carbon steel cords were observed after low-temperature thermal aging. Character and kinetics of damage in such wire ropes highly depend on the plastic elongation of the steel wires, which is significantly modified by the strain aging effect. In this paper, the static strain aging effect on heavily drawn high-carbon steel wires and their cords is experimentally studied in the 80–200 °C temperature range. The kinetics of the aging process is studied in detail. Experimental data are fit by the Johnson–Mehl–Avrami–Kolmogorov (JMAK) kinetic model. The temperature dependence of the static strain aging process is given by means of the Arrhenius equation. The associated JMAK exponents, the apparent activation energy and the pre-exponential constant are determined. Quantitative analysis of the affected strength and strain parameters is given, and based on this, the macroscopic failure mechanism is fundamentally explained.

X-Ray Fractography on Stress Corrosion Cracking of High Strength Steel

1983 ◽  
Vol 27 ◽  
pp. 213-220 ◽  
Author(s):  
Yukio Hirose ◽  
Zenjiro Yajima ◽  
Keisuke Tanaka
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Fracture Surface ◽  
High Strength Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Fatigue Fracture Surface ◽  
X Ray

X-ray fractography is a new method utilizing the X-ray diffraction technique to observe the fracture surface for the analysis of the micromechanisms and mechanics of fracture. The line broadening of X-ray diffraction profiles and the residual stress are two of the important X-ray parameters. Among them, the X-ray residual stress has been confirmed to be particularly useful for the fracture surfaces of high strength steels, and applied to the fracture surface of fracture toughness specimens and the fatigue fracture surface.

scholarly journals In Situ Determination of Phase Stress States in an Unstable Medium Manganese Duplex Steel Studied by High-Energy X-ray Diffraction

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1335
Author(s):  
Mathias Lamari ◽  
Sébastien Y. P. Allain ◽  
Guillaume Geandier ◽  
Jean-Christophe Hell ◽  
Astrid Perlade ◽  
...  
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
High Energy ◽  
Internal Stresses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Advanced High Strength Steels ◽  
Stress States

Duplex medium Mn steels are high-potential advanced high-strength steels (AHSS) for automotive construction. Their excellent forming properties stem from the specific stress partitioning between their constituting phases during deformation, namely the ferritic matrix, unstable retained austenite, and strain-induced fresh martensite. The stability of the retained austenite and the 3D stress tensors of each phase are determined simultaneously in this work by in situ high energy X-ray diffraction on synchrotron beamline during a tensile test. The role of internal stresses inherited from the manufacturing stage are highlighted for the first time as well as new insights to understand the origin of the serrations shown by these alloys.

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