scholarly journals A MÖssbauer Study of Microstructural and Chemical Changes in FE-9NI Steel During Two-Phase Tempering

1980 ◽  
Vol 3 ◽  
Author(s):  
B. Fultz ◽  
J. W. Morris
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Hyperfine Field ◽  
Mössbauer Study ◽  
Two Phase ◽  
Ni Alloys ◽  
9Ni Steel ◽  
Low Temperature Toughness ◽  
Kinetics Of ◽  
Composition Changes

ABSTRACTTwo-phase tempering of martensitic Fe-9Ni steel serves to enhance the low temperature toughness and forms austenite precipitates in this material. Hyperfine field effects in Fe-Ni alloys were systematized so that tempering induced chemical composition changes in the martensite could be quantified by Mössbauer spectrometry. The kinetics of segregation of alloy elements from the martensite into the fresh austenite can be determined simultaneously with the amount of austenite which has formed.

Efficiency of Microstructure Refinement in Ti-Based Alloys

2021 ◽  
Vol 1016 ◽  
pp. 1753-1758
Author(s):  
Sergey Zherebtsov ◽  
Nikita Stepanov ◽  
Gennady Salishchev
Keyword(s):  
Plastic Deformation ◽  
Chemical Composition ◽  
Titanium Alloys ◽  
Microstructure Evolution ◽  
Large Plastic Deformation ◽  
Two Phase ◽  
Microstructure Refinement ◽  
Kinetics Of ◽  
Rate Type ◽  
Lamellar Type

The influence of various factors on the efficiency of microstructure refinement in two-phase titanium alloys with respect to a well-known Ti-6Al-4V alloy was discussed. The kinetics of microstructure evolution in titanium alloys with a lamellar type α/β microstructure during large plastic deformation depends mainly on temperature and strain rate, type of the initial microstructure, thickness of the α lamellae, path of deformation and chemical composition. Each parameter should be controlled to provide the most efficient microstructure refinement during conventional metalforming methods.

Metallurgical Design and Development of High-Grade Line Pipe

2012 ◽  
Author(s):  
Takuya Hara ◽  
Taishi Fujishiro ◽  
Yasuhiro Shinohara ◽  
Eiji Tsuru ◽  
Naoki Doi ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Cost Savings ◽  
High Strength ◽  
Design And Development ◽  
Line Pipe ◽  
Good Balance ◽  
Low Temperature Toughness ◽  
And Control ◽  
High Deformability

The application of high-strength line pipes has enabled pipelines to operate at high pressure, generating cost savings for both gas transportation and construction. In general, high-strength line pipes require crack initiation resistance and crack arrestability at low temperatures, as well as field weldability. High strength and deformability for strain-based design and excellent sour resistance are also required. Moreover, composite properties are often required for high-strength line pipes. This paper describes our progress in this field with regard to metallurgical design and development. Metallurgical design aimed at achieving a good balance between strength, low temperature toughness and deformability for strain-based design is also described from the perspectives of grain refinement, microstructure and chemical composition. Metallurgical design focused on a good balance between strength and sour resistance in limited low chemical composition is described from the perspectives of microstructure and control to chemical composition and center segregation. These efforts have led to the development of high-strength heavy wall line pipes of API X60 to X100 grades offering excellent low temperature toughness and high deformability for stain-based design, while API grades X65 to X70 with good sour resistance have also been developed.

scholarly journals STUDY OF THE KINETICS OF HYDRATION STRUCTURING AND THE PROPERTIES OF LIME-BELITIC BINDERS BASED OF MARL

Vestnik MGSU ◽  
2016 ◽  
pp. 62-68
Author(s):  
Aleksey Dmitrievich Zhukov ◽  
Marat Orynbaevich Asamatdinov ◽  
Bakhtiyar Chimbergenovich Nurymbetov ◽  
Sharibay Nauryzbaevich Turemuratov
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Physicochemical Properties ◽  
Calcium Oxide ◽  
Raw Materials ◽  
High Strength ◽  
Dicalcium Silicate ◽  
Different Types ◽  
Materials Used ◽  
Kinetics Of

Lime-belite binder is obtained by low-temperature firing of natural marl, marling or sanding limestone and artificial lime-silica mixtures. The binder with calcium oxide also contains significant amounts of dicalcium silicate and some others materials, the composition and quantity of which depend on the chemical composition and firing temperature of the raw materials used. The authors investigated the kinetics of hydration structures and physicochemical properties of lime-based binders on the basis of belitic marl from Akburly and Porlytau. The formation of resistance is associated not only with the formation of the system of different types of structures - coagulation and crystallization, with the transition of the first to the second, but also with the different stages of formation of crystal structures. The possibility of using lime-belitic binders for the preparation of high-strength products of autoclave hardening is proved. The autoclaved binders used in the manufacture of sand-lime products are prepared with the use of mixtures consisting of 60...70 % lime-belite binder and 30...40 % ground quartz sand.

Microstructure Identification for X80 Plates/Pipes With Low Temperature Toughness and Enhanced Strain Capacity

2014 ◽  
Author(s):  
Andrea Di Schino ◽  
Lei Zheng ◽  
Chuanguo Zhang ◽  
Giorgio Porcu
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Ground Movement ◽  
Pipe Material ◽  
Cooling Process ◽  
Long Distance ◽  
Strain Capacity ◽  
Enhanced Strain ◽  
Low Temperature Toughness ◽  
Test Materials

Due to the increasing demand for natural gas, the construction of long-distance pipelines through seismically active regions or arctic regions with ground movement caused by permafrost phenomena will become more and more necessary. To guarantee the safe operation of those pipelines, the pipe material has to fulfil strain-based design requirements. Hence in longitudinal direction low yield-to-tensile ratios, high uniform elongation values and a roundhouse shape of the stress-strain curve combined with sufficient strength values in transverse direction are essential. Moreover, a satisfactory low temperature toughness has to be guaranteed. An adequate plate metallurgical design is fundamental for appropriate pipe properties achievement. As far as concerns the plate design the understanding and the control of microstructure are the key factors, achieved by an adequate steel chemical composition and proper process parameters. In the framework of a co-operation between Baosteel and Centro Sviluppo Materiali (CSM), a project has been started aimed at manufacturing X80 strain based designed pipes. As a starting point pilot trials have been carried out at Baosteel Research Center in order to produce different microstructures. Besides the steel chemical composition, the cooling process has the most significant influence on the formation of the microstructure: in order to assess the effect of the cooling process, the same rolling schedule was adopted for producing the different test materials, obtained varying the start cooling and finish cooling temperatures. The microstructure and mechanical properties of the different test materials were assessed and the best microstructure for the plates for X80 pipes with enhanced strain capacity has been identified.

A Mössbauer Study of the Amorphous System (FexNi1−x)75P16B6Al3

1980 ◽  
Vol 3 ◽  
Author(s):  
S. Bjarman ◽  
R. Wäppling ◽  
K.V. Rao
Keyword(s):  
Low Temperature ◽  
Hyperfine Field ◽  
Composition Range ◽  
Magnetic Hyperfine Field ◽  
Magnetic Behaviour ◽  
Mössbauer Study ◽  
Hyperfine Field Distribution ◽  
Amorphous System ◽  
Spin Texture ◽  
Curie Temperatures

ABSTRACTIn the system (FeXNi1−x)75P16B6Al3 an unusual magnetic behaviour is found in the composition range 0.2<x<0.3. The drastic changes seen at low temperature in the thermomagnetic measurements is found not to affect the Mössbauer spectra. From the width of the magnetic hyperfine field distribution as function of temperature there seems to be a distribution in Curie temperatures. Due to the absence of spin texture it was not possible to make a distinction between the two proposed low temperature phases although the general results favour the spin glass alternative.

Development and Production of Helical-Two-Step (HTS) Pipes: Grades Up to API X70 for Sour Service Application

2012 ◽  
Author(s):  
Djordje Mirković ◽  
Volker Flaxa ◽  
Franz Martin Knoop
Keyword(s):  
Low Temperature ◽  
Pipeline Steel ◽  
Steel Production ◽  
Standard Test ◽  
Pipe Production ◽  
Two Phase ◽  
Steel Grades ◽  
Low Temperature Toughness ◽  
Service Application ◽  
Sour Service

Within the corresponding commercial and R&D projects five microalloyed pipeline steel grades have recently been developed and processed to spiral-welded pipes. For steel grades X52, X65, and X70 the aimed tensile properties, improved sour service resistivity, and low temperature toughness up to −40°C were reliably achieved. Influence of steel cleanliness, the non-metallic inclusions in particular, on sour gas resistibility has been investigated by means of ultrasonic testing of hydrogen charged HIC (Hydrogen Induced Cracking) samples and SEM (Scanning Electron Microscope) analyses of HIC fracture surfaces. The results have been used to optimize the applied process parameter in steel production and coil processing. The ladle metallurgical treatment and soft reduction were consistently applied within narrow process tolerances enabling high steel cleanness and slab centerline quality, which are both indispensable for sour service application. Subsequent TMCP (Thermo Mechanical Processing) wide strip hot rolling and cooling parameters were selected to prevent a two-phase finish rolling and to obtain a predominating acicular ferritic microstructure. For pipe production, attention was paid to minimize the residual stresses, due to both pipe-forming and welding. The alloying approach is based on the classical sour lean NbTi steel composition, modified by varying Cu, Ni, Cr, and Mo contents to achieve the targeted specification. The processed spiral-welded pipes were formed to diameters between 762 and 1372 mm with a wall thickness of 13.7 to 16.0 mm. CVN (Charpy V-Notch) values were higher than 360 J/cm2 and DWTT (Drop Weight Tear Test) higher than 60% SA (Shear Area) at −40°C. The samples also showed outstanding HIC resistivity. Being proved with standard test conditions according to NACE TM0284 solution A, the CAR (Crack Area Ratio) average value of pipe samples was less than 1% for grades up to X65 and less than 5% for X70 grades. The 4-point-bending SSC (Sulphide Stress Cracking) tests at 80% of SMYS according to NACE TM0177 and ASTM G39 showed no SSC cracks for all projects. Finally, the results of one specific R&D project are presented to demonstrate that even for API X70 grade spiral-welded pipes (OD 1016×16 mm) mechanical properties, e.g. high-strength, ductility, and low temperature toughness has been successfully combined with sour service resistivity.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

A Comparison of Tem and Apfim to the Interpretation of Modulated Microstructures

1985 ◽  
Vol 43 ◽  
pp. 70-71
Author(s):  
M.G. Burke ◽  
M.K. Miller
Keyword(s):  
Low Temperature ◽  
Microstructural Characterization ◽  
Superlattice Reflection ◽  
High Volume ◽  
Atom Probe ◽  
Dark Field ◽  
Miscibility Gap ◽  
Second Phase ◽  
Two Phase ◽  
Probe Field

Interpretation of fine-scale microstructures containing high volume fractions of second phase is complex. In particular, microstructures developed through decomposition within low temperature miscibility gaps may be extremely fine. This paper compares the morphological interpretations of such complex microstructures by the high-resolution techniques of TEM and atom probe field-ion microscopy (APFIM).The Fe-25 at% Be alloy selected for this study was aged within the low temperature miscibility gap to form a <100> aligned two-phase microstructure. This triaxially modulated microstructure is composed of an Fe-rich ferrite phase and a B2-ordered Be-enriched phase. The microstructural characterization through conventional bright-field TEM is inadequate because of the many contributions to image contrast. The ordering reaction which accompanies spinodal decomposition in this alloy permits simplification of the image by the use of the centered dark field technique to image just one phase. A CDF image formed with a B2 superlattice reflection is shown in fig. 1. In this CDF micrograph, the the B2-ordered Be-enriched phase appears as bright regions in the darkly-imaging ferrite. By examining the specimen in a [001] orientation, the <100> nature of the modulations is evident.

Sign in / Sign up

Export Citation Format

Share Document