scholarly journals Non-equilibrium solidification and microsegregation in centrifugally cast high speed steel for rolls

2018 ◽  
Vol 54 (1) ◽  
pp. 59-66 ◽  
Author(s):  
U. Klancnik ◽  
B. Kosec ◽  
P. Mrvar ◽  
J. Medved
Keyword(s):  
Electron Microscopy ◽  
High Speed ◽  
Light And Electron Microscopy ◽  
High Speed Steel ◽  
Scanning Calorimetry ◽  
Centrifugally Cast ◽  
Eutectic Carbides ◽  
Thermo Calc Software ◽  
Equilibrium Solidification ◽  
Non Equilibrium

When regarding as-cast microstructures of highly alloyed metals, microsegregation of alloying elements is a common feature resulting from non-equilibrium conditions during solidification. The aim of this work is to predict the occurrence and severity of microsegregation in highly alloyed, centrifugally cast high speed steel used for rolls. The prediction was performed using thermodynamic Scheil-Gulliver modelling with Thermo-Calc software. The modelled predictions were then compared with differential scanning calorimetry, X-ray diffraction, light and electron microscopy with energy dispersive spectroscopy, all performed on an as-cast roll shell. Results show that chromium, molybdenum and vanadium have the highest tendency to microsegregation. Vanadium tends to form negative microsegregation, while molybdenum and chromium form positive microsegregation. Scanning electron microscopy revealed the presence of complex eutectic carbides, confirming the Scheil-Gulliver non-equilibrium solidification path via two main successive eutectic reactions.

scholarly journals Effects of Homogenization Conditions on the Microstructure Evolution of Aluminium Alloy EN AW 8006

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 419
Author(s):  
Maja Vončina ◽  
Kristijan Kresnik ◽  
Darja Volšak ◽  
Jožef Medved
Keyword(s):  
Aluminium Alloy ◽  
Thermodynamic Simulation ◽  
Casting Process ◽  
Optical Microscope ◽  
Scanning Calorimetry ◽  
Energy Dispersion Spectrometer ◽  
Thermo Calc Software ◽  
Equilibrium Solidification ◽  
Equilibrium Phases ◽  
Non Equilibrium

The industrial production of products, such as foil and aluminium alloy strips, begins with the production of semi-finished products in the form of slabs. These are produced by the continuous casting process, which is quick and does not allow the equilibrium conditions of solidification. Non-homogeneity—such as micro and macro segregation, non-equilibrium phases and microstructural constituents, as well as stresses arising during non-equilibrium solidification—are eliminated by means of homogenization annealing. In this way, a number of technological difficulties in the further processing of semi-finished products can be avoided. The aim of this research was the optimization of the homogenization annealing of the EN AW 8006 alloy. With the Thermo-Calc software, a thermodynamic simulation of equilibrium and non-equilibrium solidification was performed. Differential scanning calorimetry (DSC) was performed on selected samples in as-cast state and after various regimes of homogenization annealing and was used for the simulation of homogenization annealing. Using an optical microscope (OM), a scanning electron microscope (SEM) and an energy dispersion spectrometer (EDS), the microstructure of the samples was examined. Based on the results, it was concluded that homogenization annealing has already taken place after 8 h at 580 °C to the extent, that the material is then suitable for further processing.

Mechanical Analysis of Low and High Chromium Steels Used in Hot Strip Work Rolls

2018 ◽  
Vol 279 ◽  
pp. 3-9
Author(s):  
Fethi Benkhenafou ◽  
Ines Fernández Pariente ◽  
F.Javier Belzunce ◽  
Abdelkader Ziadi ◽  
Ming Quan Shi ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
High Speed ◽  
Volume Fraction ◽  
Research Work ◽  
High Speed Steel ◽  
Nodular Cast Iron ◽  
High Chromium ◽  
Eutectic Carbides ◽  
Hot Strip ◽  
Conventional Heat Treatment

Microstructure, hardness and fracture toughness of low and high chromium high speed steel used in hot strip mills and subjected to conventional heat treatment have been examined. The influence of tempering temperatures on the mechanical properties of these products, determined using tensile and fracture toughness tests, was studied in this research work. The developed microstructures have been characterized by XRD, optical microscopy and SEM examinations. Macrohardness and microhardness of the specimens have been evaluated by Vickers indentation technique. The fracture toughness of these products was investigated using the rupture weight on 3 points bending specimens. The plane strain fracture toughness KIc and the fracture strength were measured for each alloy. The shell is high harness high speed steels, and the core is nodular cast iron. It was found that most fracture occurred in the eutectic carbides formed by the high content alloy element, such as Mo,V,Cr, but that for the alloys with a reduced volume fraction of eutectic carbides, a small amount of crack propagation occurred in the austenitic dendrites.

A Study of the Carbides in High-Speed Steel Rolls

2010 ◽  
Vol 638-642 ◽  
pp. 3356-3361 ◽  
Author(s):  
Yi Kun Luan ◽  
Nan Nan Song ◽  
Xiu Hong Kang ◽  
Dian Zhong Li
Keyword(s):  
Heat Treatment ◽  
Grain Boundaries ◽  
High Speed ◽  
Solidification Rate ◽  
High Speed Steel ◽  
Eutectic Carbides ◽  
Complex Carbides ◽  
Steel Rolls ◽  
Alloy Concentration

Carbides in HSS roll were studied systematically. The results showed that there were two kinds of carbides in HSS roll, 1st and 2nd carbides. 1st eutectic carbides included the chrysanthemum-like MC mainly consisting of V and the plate-like M2C rich in Mo. 2nd carbides were complex carbides, concentrating Fe, Cr, Mo and V elements. The morphology, distribution and alloy concentration of the 1st eutectic carbides were studied using OM, SEM and EDS. During heat treatment, evolution of the 1st eutectic carbides was analyzed. It was found that the MC carbides had no change in morphology, components and distribution, while the M2C carbides decomposed to M6C and MC. In order to improve the properties of HSS, a method of increasing solidification rate was defined to refine the eutectic carbides. After refinement, the eutectic carbides distributed both along the grain boundaries and inside the grains.

Influence of rare earths on eutectic carbides in AISI M2 high speed steel

2012 ◽  
Vol 30 (10) ◽  
pp. 1075-1078 ◽  
Author(s):  
Xuefeng ZHOU ◽  
Xiaoyan YIN ◽  
Feng FANG ◽  
Jianqing JIANG ◽  
Wanglong ZHU
Keyword(s):  
Rare Earths ◽  
High Speed ◽  
High Speed Steel ◽  
Eutectic Carbides ◽  
M2 High Speed Steel

scholarly journals AutoCLEM: An Automated Workflow for Correlative Live-Cell Fluorescence Microscopy and Cryo-Electron Tomography

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Xiaofeng Fu ◽  
Jiying Ning ◽  
Zhou Zhong ◽  
Zandrea Ambrose ◽  
Simon Charles Watkins ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Speed ◽  
Electron Tomography ◽  
Light And Electron Microscopy ◽  
Live Cell ◽  
Host Cells ◽  
Spatiotemporal Information ◽  
Fluorescence Light ◽  
Correlation Process ◽  
Electron Imaging

AbstractCorrelative light and electron microscopy (CLEM) combines the strengths of both light and electron imaging modalities and enables linking of biological spatiotemporal information from live-cell fluorescence light microscopy (fLM) to high-resolution cellular ultra-structures from cryo-electron microscopy and tomography (cryoEM/ET). This has been previously achieved by using fLM signals to localize the regions of interest under cryogenic conditions. The correlation process, however, is often tedious and time-consuming with low throughput and limited accuracy, because multiple correlation steps at different length scales are largely carried out manually. Here, we present an experimental workflow, AutoCLEM, which overcomes the existing limitations and improves the performance and throughput of CLEM methods, and associated software. The AutoCLEM system encompasses a high-speed confocal live-cell imaging module to acquire an automated fLM grid atlas that is linked to the cryoEM grid atlas, followed by cryofLM imaging after freezing. The fLM coordinates of the targeted areas are automatically converted to cryoEM/ET and refined using fluorescent fiducial beads. This AutoCLEM workflow significantly accelerates the correlation efficiency between live-cell fluorescence imaging and cryoEM/ET structural analysis, as demonstrated by visualizing human immunodeficiency virus type 1 (HIV-1) interacting with host cells.

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