Low temperature fracture properties of DIN 22NiMoCr37 steel in fine-grained bainite and coarse-grained tempered embrittled martensite microstructures

2008 ◽  
Vol 75 (8) ◽  
pp. 2480-2513 ◽  
Author(s):  
M.J. Balart ◽  
J.F. Knott
Keyword(s):  
Low Temperature ◽  
Coarse Grained ◽  
Fracture Properties ◽  
Fine Grained ◽  
Temperature Fracture

Low Temperature Fracture Properties of Polyphosphoric Acid Modified Asphalt Mixtures

2012 ◽  
Vol 24 (8) ◽  
pp. 1089-1096 ◽  
Author(s):  
Eyoab T. Zegeye ◽  
Ki H. Moon ◽  
Mugur Turos ◽  
Timothy R. Clyne ◽  
Mihai O. Marasteanu
Keyword(s):  
Low Temperature ◽  
Polyphosphoric Acid ◽  
Asphalt Mixtures ◽  
Fracture Properties ◽  
Modified Asphalt ◽  
Temperature Fracture

High-Ti magnetite in some fine-grained carbonatites and the magmatic implications

2002 ◽  
Vol 66 (3) ◽  
pp. 379-384 ◽  
Author(s):  
D. K. Bailey ◽  
S. Kearns
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Composition Range ◽  
Volcanic Rocks ◽  
Coarse Grained ◽  
Slow Cooling ◽  
Fine Grained ◽  
Narrow Composition Range ◽  
Fast Quenching ◽  
Temperature Crystallization

AbstractMagnetite is present in most carbonatites, and in the most abundant and best-known form of carbonatite, coarse-grained intrusions, it typically falls in a narrow composition range close to Fe3O4. A fine-grained carbonatite from Zambia contains magnetites with an extraordinary array of compositions (from 18–1% TiO2, 10–2% Al2O3, and 16–4% MgO) outranging previously-reported examples. Zoning trends are from high TiO2 to high Al2O3 and MgO. No signs of exsolution are seen. Checks on similar rocks from Germany, Uganda and Tanzania reveal magnetites with comparable compositions, ranges, and zoning. Magnetites from alkaline and alkaline ultramafic silicate volcanic rocks cover only parts of this array. Magnetite analyses from some other fine-grained carbonatites, reported in the literature, fall in the same composition field, suggesting that this form of carbonatite may be distinctive. The chemistry and zoning would be consonant with rapid high-temperature crystallization in the carbonatite melts, with the lack of exsolution pointing to fast quenching: this contrasts with coarse-grained intrusive carbonatites, in which the magnetite compositions are attributed to slow cooling, with final equilibration at low temperature. In some complexes, both forms of carbonatite, with their different magnetite compositions, are represented.

Microstructure and Texture of Mg-Based AZ Alloys after Heavy Deformation under Cyclic Strain Path Change Conditions

2008 ◽  
Vol 584-586 ◽  
pp. 565-570 ◽  
Author(s):  
Jan Pospiech ◽  
Andrzej Korbel ◽  
Jan T. Bonarski ◽  
Włodzimierz Bochniak ◽  
Leszek Tarkowski
Keyword(s):  
Low Temperature ◽  
Texture Evolution ◽  
New Technology ◽  
Metal Flow ◽  
Cyclic Strain ◽  
Optical Observations ◽  
Coarse Grained ◽  
Extrusion Force ◽  
Fine Grained ◽  
Heterogeneous Deformation

The effects associated with the change of the deformation path - such as the replacement of homogeneous multi-slip by heterogeneous deformation and a decrease of global strain hardening - have been utilised in the metal forming operation termed KOBO technology. In the case of extrusion it consists in reversible, cyclic twisting of a billet under the extrusion force. The technology enables extrusion of metals with very large deformation in one operation at low temperature. A complex scheme of straining, large cumulated deformation and low temperature of the process results in a fine grained microstructure of the extruded material (product). The new technology requires detailed studies of the mechanism of the plastic deformation with the specific geometry of the zone of metal flow during extrusion. Essential in these studies is the information on the texture and microstructure in the deformation zone. The aim of this work is therefore to disclose the deformation mechanisms on the basis of the observations of microstructure and texture evolution in the zone of plastic flow of the extrudate. Coarse grained polycrystalline billets of magnesium alloys AZ31 were extruded by KOBO at room temperature and also by a conventional method at about 400°C. Methods of texture topography as well as optical observations reveal the specific microstructure and texture in mezzo and micro scale of heavily deformed material after extrusion. It is worth mentioning that the KOBO process leads to compact and rather homogeneous extrudates even in the case of AZ alloys. These hexagonal metals cannot be cold-formed to a high reduction with conventional techniques.

Microstructural and mechanical properties of ternary Mo-Si-B alloys resulting from different processing routes

2011 ◽  
Vol 1295 ◽  
Author(s):  
Manja Krüger ◽  
Martin Heilmaier ◽  
Veronika Shyrska ◽  
Petr I. Loboda
Keyword(s):  
Zone Melting ◽  
Coarse Grained ◽  
Processing Route ◽  
Chemical Compositions ◽  
Homogeneous Microstructure ◽  
Fine Grained ◽  
Intermetallic Matrix ◽  
Oxidation Performance ◽  
Embedded Particles ◽  
Temperature Fracture

ABSTRACTMo-base silicide alloys take advantage of their outstanding intrinsic properties, notably the high melting point and, thus, their excellent mechanical and creep strength. We demonstrate how the processing route influences the microstructure and consequently the mechanical and oxidation behaviour. Therefore two fabrication routes, a powder metallurgical (PM) and a zone melting (ZM) process, both starting from elemental powders, were used to prepare several Mo-Si-B alloys with varying chemical compositions. While PM processing leads to an ultrafine microstructure with a continuous Mo solid solution (“α-Mo”) matrix and embedded particles of the two intermetallic compounds Mo3Si and Mo5SiB2, the directionally solidified (ZM) materials possess a coarse grained structure composed of an intermetallic matrix with dendritic islands of α-Mo. A comparative assessment of the mechanical behaviour of the alloys utilizing both the Vickers indentation fracture (VIF) technique and three-point bending tests emphasizes the beneficial effect of a continuous Mo matrix resulting in increased room temperature fracture toughness and a reduction of the brittle-to-ductile-transition-temperature (BDTT). Likewise, the positive effect of the fine grained and homogeneous microstructure on oxidation performance is shown by the evaluation of mass change during heat treatment at 1100°C.

scholarly journals Effect of Martensite–Austenite Constituent on Low-Temperature Toughness in YS 500 MPa Grade Steel Welds

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 638 ◽  
Author(s):  
In Kim ◽  
Hyunbin Nam ◽  
Myungjin Lee ◽  
Daegeun Nam ◽  
Yeongdo Park ◽  
...  
Keyword(s):  
Low Temperature ◽  
Heat Affected Zone ◽  
Coarse Grained ◽  
Fine Grained ◽  
Direct Quenching ◽  
Austenite Grain ◽  
Low Temperature Toughness ◽  
Steel Welds ◽  
Quenching And Tempering ◽  
Grade Steel

The effect of martensite–austenite (M–A) constituents and simulated microstructure on low-temperature toughness was investigated in YS 500 MPa grade structural steel welds. The specimens were fabricated using a direct quenching and tempering process. After simulated weld thermal cycles, the coarse-grained heat-affected zone (CGHAZ) and intercritically reheated coarse-grained heat-affected zone (IRCGHAZ) were produced using a Gleeble tester and real welded joint to support the simulation results. The largest low-temperature toughness was observed in the fine-grained heat-affected zone (FGHAZ) owing to the fine-ferrite microstructure. However, the toughness decreased in the IRCGHAZ because of the slender morphology of the M–A constituents that formed primarily along the prior austenite grain boundaries in the IRCGHAZ.

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