The role of thermal contraction stresses associated to inclusions in the formation of the final microstructure of weld metal deposits

1987 ◽  
Vol 22 (1) ◽  
pp. 351-355 ◽  
Author(s):  
M. Ferrante ◽  
K. Akune ◽  
M. Odainai
Keyword(s):  
Weld Metal ◽  
Thermal Contraction ◽  
Final Microstructure

The Influence of Oxygen-Rich Inclusions on the Nature of Austenite Decomposition Products of Weld Metal Deposits

1983 ◽  
Vol 21 ◽  
Author(s):  
M. Ferrante ◽  
K. Akune
Keyword(s):  
Weld Metal ◽  
Catalytic Effect ◽  
Thermal Contraction ◽  
Austenite Decomposition ◽  
Decomposition Products ◽  
The Matrix

ABSTRACTRecent studies carried out on weld metal have called attention to the role of oxygen-rich inclusions on austenite decomposition. This investigation describes some evidences of the catalytic effect of dislocations upon the γ → α transformation. These defects are generated at the matrix inclusion interface and its presence has been ascertained by TEM. Estimates of the stresses arising from differences in thermal contraction between inclusion and matrix on cooling confirm microstructural observations.

scholarly journals Role of Sintering Temperature in Production of Nepheline Ceramics-Based Geopolymer with Addition of Ultra-High Molecular Weight Polyethylene

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1077
Author(s):  
Romisuhani Ahmad ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Wan Mastura Wan Ibrahim ◽  
Kamarudin Hussin ◽  
Fakhryna Hannanee Ahmad Zaidi ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Sintering Temperature ◽  
Ceramic Materials ◽  
Microstructural Properties ◽  
Sintering Process ◽  
Final Microstructure ◽  
Change Of Microstructure ◽  
Ultra High Molecular Weight

The primary motivation of developing ceramic materials using geopolymer method is to minimize the reliance on high sintering temperatures. The ultra-high molecular weight polyethylene (UHMWPE) was added as binder and reinforces the nepheline ceramics based geopolymer. The samples were sintered at 900 °C, 1000 °C, 1100 °C, and 1200 °C to elucidate the influence of sintering on the physical and microstructural properties. The results indicated that a maximum flexural strength of 92 MPa is attainable once the samples are used to be sintered at 1200 °C. It was also determined that the density, porosity, volumetric shrinkage, and water absorption of the samples also affected by the sintering due to the change of microstructure and crystallinity. The IR spectra reveal that the band at around 1400 cm−1 becomes weak, indicating that sodium carbonate decomposed and began to react with the silica and alumina released from gels to form nepheline phases. The sintering process influence in the development of the final microstructure thus improving the properties of the ceramic materials.

High Heat Input Welding of 12Cr-6Ni-2.5Mo Supermartensitic Stainless Steel

2003 ◽  
Author(s):  
Ragnhild Aune ◽  
Hans Fostervoll ◽  
Odd Magne Akselsen
Keyword(s):  
Weld Metal ◽  
Stainless Steels ◽  
Heat Affected Zone ◽  
Heat Input ◽  
High Heat ◽  
Maximum Heat ◽  
Final Microstructure ◽  
Girth Welding ◽  
High Heat Input ◽  
Longitudinal Seam

In conventional welding of 13% Cr supermartensitic stainless steels, the normal microstructure that forms on cooling is martensite. Although high heat input tends to give a certain coarsening of the final microstructure, the eventual accompanying loss in toughness is not known. The present study was initiated to examine the effect of heat input on weld metal and heat affected zone mechanical properties of a 12Cr-6Ni-2.5Mo grade. The results obtained showed that the notch toughness is low (25 J) and independent of heat input for the weld metal, while it is reduced with increasing heat input for fusion line and the heat affected zone locations. Subsequent post weld heat treatment gave a substantial increase in toughness for all notch locations. Based on these results, indications are that a specified maximum heat input is not applicable in welding of supermartensitic stainless steels, allowing more production efficient techniques to be used, both in longitudinal seam and girth welding.

The role of addition of Ni on the microstructure and mechanical behaviour of C-Mn weld metals

Exacta ◽  
2008 ◽  
Vol 5 (1) ◽  
Author(s):  
Vicente Braz da Trindade ◽  
João Da Cruz Payão ◽  
Luís Felile Guimarães Souza ◽  
Ronaldo Da Rocha Paranhos
Keyword(s):  
Heat Treatment ◽  
Weld Metal ◽  
Nickel Content ◽  
Stress Relief ◽  
Impact Testing ◽  
Microstructural Refinement ◽  
Weld Metals ◽  
The Impact ◽  
Submerged Arc

The aim in this work is to study the influence of nickel content (as-welded state and after stress relief heat treatment) on the microstructure and toughness of CMn weld metals obtained with submerged arc welding. The nickel content vary between 0.50 wt.% and 3.11 wt.%. The microstructures were observed using optical microscopy (OM) and scanning electron microscopy (SEM). The toughness was evaluated by Charpy-V impact testing in samples cut transversally to the weld bead. The impact energy showed that nickel content up to 1 wt.% improves the toughness due to the increase of the acicular ferrite (AF) content and microstructural refinement. On the other hand, higher nickel contents have a deleterious effect on the toughness due to the presence of the microconstituent martensite-austenite (M-A) in the weld metal. The stress relief heat treatment did not improve too much the weld metal toughness, even the M-A suffering decomposition (ferrite+carbide). This may be explained by the precipitation of carbides along the boundaries of the ferrite.

The Role of Continuous Cooling Transformation Diagrams in Material Design for High Strength Oil and Gas Transmission Pipeline Steels

2006 ◽  
Author(s):  
Douglas G. Stalheim ◽  
Govindarajan Muralidharan
Keyword(s):  
Oil And Gas ◽  
Alloy Composition ◽  
Processing Route ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Effective Manner ◽  
Final Microstructure ◽  
Cct Diagrams ◽  
Transmission Pipelines

The economical, environmental, and safe movement of gas and oil to the marketplace requires transmission pipelines to be designed to operate at higher pressures and/or with improved toughness over a variety of temperature ranges. To meet the higher strength and toughness specification requirements of these transmission pipelines, appropriate materials and processes must be used in their design and construction. This includes selection of appropriate alloy composition, processing routes, microstructure control, and cost. A continuous cooling transformation (CCT) diagram is a tool that can be used to select alloy composition and processing route in order to obtain a specific, desirable microstructure for transmission linepipe steels in a cost-effective manner. In the past, CCT diagrams were developed experimentally under laboratory conditions, thus requiring extensive time and effort. However, with the vast data available and improved computational tools, reasonably accurate computer generated CCT diagrams can be produced quickly. These computer generated diagrams can give the materials design engineer a reasonable understanding of the effect of subjecting a given alloy to various processing routes and hence the resultant microstructures. Since final microstructure is a key variable in determining the linepipe steel material properties, the chosen alloy/processing route and its effect on the final microstructure needs to be understood. This paper will discuss the role of CCT diagrams in the design of steels (cost, alloy, processing, and microstructure) for oil and gas transmission pipelines. Examples of computer generated CCT digrams for various API alloy designs are included.

The role of thermal contraction crack polygons in cold-desert fluvial systems

2008 ◽  
Vol 20 (6) ◽  
pp. 565-579 ◽  
Author(s):  
Joseph S. Levy ◽  
James W. Head ◽  
David R. Marchant
Keyword(s):  
Thermal Contraction ◽  
Patterned Ground ◽  
Sediment Grain Size ◽  
Cold Desert ◽  
Fluvial Systems ◽  
Hyporheic Zones ◽  
Continuous Presence ◽  
And Storage ◽  
Composite Wedge

AbstractThermal contraction crack polygons modify the generation, transport, and storage of water in Wright Valley gullies. Water generation is contributed to by trapping of windblown snow in polygon troughs. Water transport is modified by changes to the ice-cement table and active layer topography caused by polygon trough formation. Water storage is modified by sediment grain-size distribution within polygons in gully distal hyporheic zones. Patterned ground morphological variation can serve as an indicator of fluvial modification, ranging from nearly unmodified composite-wedge polygons to polygons forming in association with gully channels. Thermal contraction crack polygons may also constrain the gully formation sequence, suggesting the continuous presence of permafrost beneath the Wright Valley gullies during the entire period of gully emplacement. This analysis provides a framework for understanding the relationships between polygons and gullies observed on Mars. If comparable stratigraphic relationships can be documented, the presence of an analogous impermeable ice-cemented layer beneath the gullies can be inferred, suggesting an atmospheric source for Martian gully-carving fluids.

Low carbon steel weld metal microstructures: The role of oxygen and manganese

1987 ◽  
Vol 9 (3) ◽  
pp. 253-267 ◽  
Author(s):  
P. F. Chaveriat ◽  
G. S. Kim ◽  
S. Shah ◽  
J. E. Indacochea
Keyword(s):  
Carbon Steel ◽  
Weld Metal ◽  
Low Carbon Steel ◽  
Steel Weld ◽  
Low Carbon ◽  
Steel Weld Metal

Faceting behavior of Al2O3 in the presence of glassy phase

1987 ◽  
Vol 45 ◽  
pp. 152-153
Author(s):  
Y. Kouh Simpson
Keyword(s):  
Liquid Phase ◽  
Glass Phase ◽  
Glassy Phase ◽  
Liquid Phase Sintering ◽  
Sintering Process ◽  
Final Microstructure ◽  
Amorphous Glass ◽  
Glass Interface ◽  
Energy Consideration

It is well known that A1203 can reach near-theoretical density by a liquid-phase sintering process in which an amorphous glass phase containing SiO2, CaO and Al2O3 helps density Al2O3. Understanding the faceting behavior of Al2O3 in the presence of such a glass phase is important since the movement of the facets and the type of facets that form during the liquid-phase sintering process determine the final microstructure of the grain boundaries that ultimately control the properties of Al2O3 compacts. As a part of a larger study on the role of impurities in the sintering process of Al2O3 compacts, a new investigation has been carried out to examine the nature and the type (e.g. facet planes) of the crystalline Al2O3, / amorphous glass interface in systematic experiments in which densification aids such as SiO2, CaO and MgO are reacted with single crystal Al2O3. Substantial anisotropy, both from an energy consideration and a kinetics consideration, in the Al2O3/ glass interface is to be expected, and has been observed in this investigation.

scholarly journals The role of addition of Ni on the microstructure and mechanical behaviour of C-Mn weld metals DOI: 10.5585/exacta.v5i1.1037

Exacta ◽  
2008 ◽  
Vol 5 (1) ◽  
Author(s):  
Vicente Braz da Trindade ◽  
João Da Cruz Payão ◽  
Luís Felile Guimarães Souza ◽  
Ronaldo Da Rocha Paranhos
Keyword(s):  
Heat Treatment ◽  
Weld Metal ◽  
Nickel Content ◽  
Stress Relief ◽  
Impact Testing ◽  
Microstructural Refinement ◽  
Weld Metals ◽  
The Impact ◽  
Submerged Arc

The aim in this work is to study the influence of nickel content (as-welded state and after stress relief heat treatment) on the microstructure and toughness of CMn weld metals obtained with submerged arc welding. The nickel content vary between 0.50 wt.% and 3.11 wt.%. The microstructures were observed using optical microscopy (OM) and scanning electron microscopy (SEM). The toughness was evaluated by Charpy-V impact testing in samples cut transversally to the weld bead. The impact energy showed that nickel content up to 1 wt.% improves the toughness due to the increase of the acicular ferrite (AF) content and microstructural refinement. On the other hand, higher nickel contents have a deleterious effect on the toughness due to the presence of the microconstituent martensite-austenite (M-A) in the weld metal. The stress relief heat treatment did not improve too much the weld metal toughness, even the M-A suffering decomposition (ferrite+carbide). This may be explained by the precipitation of carbides along the boundaries of the ferrite.

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