A novel Cu-Ni added medium Mn steel: Precipitation of Cu-rich particles and austenite reversed transformation occurring simultaneously during ART annealing
“…Based on the TEM image (Figure 1(b)), the particles can be readily categorised into two different groups: the interconnected particles along the grain boundaries and nanoscale globular ones within the ferrite matrix. According to the sites, morphologies and selected area diffraction pattern (SADP) of these particles, the interconnected and nanoscale globular particles were preliminarily determined as M23C6 and -Cu, respectively, which was corroborated well with the published literatures [21-24]. Figure 1 (a) Optical microstructure and (b) TEM image of BM.…”
The microstructural evolution, mechanical and electrochemical properties of the rotary friction welding joint of 1MnCrMoNi maraging steel were investigated after post-weld heat treatment (PWHT). The joint could be divided into two zones: weld zone and thermo-mechanically affected zone. After PWHT, the parallel alignment of the laths turned 'blurred'; sub-grain and cell structure appeared; M23C6 and ε-Cu precipitated, respectively; the joint was softened. But the microhardness was still higher than that of base materials and distributed unevenly. The closer it was to the weld centre, the higher the microhardness was. No deformation occurred in the joints during tensile test, indicating the excellent bonding strength. PWHT process slightly reduced the impact toughness and corrosion resistance of the joint.
“…Based on the TEM image (Figure 1(b)), the particles can be readily categorised into two different groups: the interconnected particles along the grain boundaries and nanoscale globular ones within the ferrite matrix. According to the sites, morphologies and selected area diffraction pattern (SADP) of these particles, the interconnected and nanoscale globular particles were preliminarily determined as M23C6 and -Cu, respectively, which was corroborated well with the published literatures [21-24]. Figure 1 (a) Optical microstructure and (b) TEM image of BM.…”
The microstructural evolution, mechanical and electrochemical properties of the rotary friction welding joint of 1MnCrMoNi maraging steel were investigated after post-weld heat treatment (PWHT). The joint could be divided into two zones: weld zone and thermo-mechanically affected zone. After PWHT, the parallel alignment of the laths turned 'blurred'; sub-grain and cell structure appeared; M23C6 and ε-Cu precipitated, respectively; the joint was softened. But the microhardness was still higher than that of base materials and distributed unevenly. The closer it was to the weld centre, the higher the microhardness was. No deformation occurred in the joints during tensile test, indicating the excellent bonding strength. PWHT process slightly reduced the impact toughness and corrosion resistance of the joint.
“…), such that the amount of austenite transformed to martensite decreased. Furthermore, the WR process resulted in high dislocation density (Figure 9), which contributed to stabilizing the retained austenite [23]. With all these favorable factors, it is reasonable to believe that warm rolling has the capability of retaining a significant fraction of austenite in the microstructure.…”
Section: Influencing Factors Of Chemical Composition and Processing On The Austenite Reversion In Mmnsmentioning
confidence: 99%
“…After ART annealing at 650 • C for 1 h, the RA fraction of Cu-containing MMnS (Fe-0.05C-4.9Mn-0.6Si-1.55Ni-1.22Cu) exceeded 23.2%, which is more than two times the reference MMnS (Fe-0.05C-4.9Mn-0.5Si-1.44Ni, 10.7%). Yan et al [23] reported the effect of 0.93 wt. % Ni and 1.4 wt.…”
Developing medium-Mn steels (MMnS) demands a better understanding of the microstructure evolution during thermo-mechanical treatments (TMTs). This study demonstrates the relationship among processing, microstructure, and mechanical properties of a warm-rolled medium-Mn steel (MMnS) containing 1.5 wt. % Cu and 1.5 wt. % Ni. After short-time warm rolling (WR) in an intercritical temperature range, a significant quantity (40.6 vol.%) of austenite was reverted and retained after air cooling. The microstructure and tensile properties of the WR specimens were compared with two typical process routes, namely hot rolling+ cold rolling+ annealing+ tempering (CRAT) and warm rolling+ annealing+ tempering (WRAT). The WR specimen exhibited comparable tensile properties with the CRAT specimens (967 MPa yield strength, 1155 MPa tensile strength, 23% total elongation), with a remarkably shortened process route, which was derived from the dislocation accumulation and austenite reversion during rolling. The WR route stands out among the traditional CRAT and the extended WRAT routes for its excellent tensile properties and compact processing route.
The preparation of nanostructured carbon materials from chosen biomass through hydrothermal carbonization and pyrolysis processes by optimizing the reaction conditions is one of the bases for applying the product in certain of the development activities. The finished product more or less reflects the raw material and the way of preparation. Among the many products, carbon quantum dots (CQDs) have gained importance due to their bolstered characteristics and facile preparation. CQDs are zero‐dimensional (0D) nanomaterials which attracted attention in the recent past due to their excellent water solubility, unique optical properties, good electrical conductivity, eco‐friendliness, and biocompatibility. Small‐sized CQDs offer high surface area per unit volume, strong tunable fluorescence, photo‐luminescent emissions, and semiconducting properties. In this paper, identification of ideal raw materials, process parameters being followed in the preparation of CQDs through hydrothermal carbonization and pyrolysis techniques, and the properties of the resultant CQDs commensurate with the nature of process are reviewed.
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