Study of the microstructure of electrotechnical anisotropic steel with accelerated cooling

On the basis of the conducted research, a complex of scientific and technological methods has been developed for various technological processes (thermomechanical processing with accelerated cooling, quenching from rolling and separate furnace heating with high-temperature tempering). The developed method provides the formation of the structure of acceptable heterogeneity and anisotropy according to different morphological and crystallographic parameters throughout the thickness of rolled products up to 100 mm from low alloy steels with a yield strength of at least 315–460 MPa and up to 60 mm from economically alloyed steels with a yield strength of at least 500–750 MPa. The paper presents results of the industrial implementation of hot plastic deformation and heat treatment schemes for the production of cold rolled steel sheet with yield strength of at least 315–750 MPa for the Arctic. The structure of sheet metal thickness is given, providing guaranteed characteristics of strength, ductility, cold resistance, weldability and crack resistance.

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Modeling of steel hardening process at thermal and mechanical treatment

Voprosy Materialovedeniya ◽

10.22349/1994-6716-2018-96-4-07-13 ◽

2019 ◽

pp. 7-13

Author(s):

A. S. Oryshchenko ◽

V. A. Malyshevsky ◽

E. A. Shumilov

Keyword(s):

Mechanical Treatment ◽

Thermomechanical Processing ◽

High Strength Steels ◽

High Strength ◽

Accelerated Cooling ◽

Rolling Mills ◽

Hardening Process ◽

Deformation Parameters ◽

Research Complex ◽

Steel Hardening

The article deals with modeling of thermomechanical processing of high-strength steels at the Gleeble 3800 research complex, simulating thermomechanical processing with various temperature and deformation parameters of rolling and with accelerated cooling to a predetermined temperature. The identity of steel hardening processes at the Gleeble 3800 complex and specialized rolling mills, as well as the possibility of obtaining steels of unified chemical composition, are shown.

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Examining Ferromagnetic Materials Subjected to a Static Stress Load Using the Magnetic Method

Materials ◽

10.3390/ma14133455 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3455

Author(s):

Tomasz Chady ◽

Ryszard Łukaszuk

Keyword(s):

Statistical Analysis ◽

Measurement System ◽

Rolling Direction ◽

Hysteresis Loops ◽

Ferromagnetic Materials ◽

Static Stress ◽

Magnetic Method ◽

Experimental Examination ◽

Stress Load ◽

Anisotropic Steel

This paper discusses the experimental examination of anisotropic steel-made samples subjected to a static stress load. A nondestructive testing (NDT) measurement system with a transducer, which enables observation of local hysteresis loops and detection of samples’ inhomogeneity, is proposed. Local hysteresis loops are measured on two perpendicular axes, including one parallel to the rolling direction of the samples. The results confirm that the selected features of the local hysteresis loops provide important information about the conditions of ferromagnetic materials. Furthermore, it is shown that the selected parameters of the statistical analysis of the achieved measurements are beneficial for evaluating stress and fatigue changes induced in the material.

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Dynamic Transformation of Austenite at Temperatures above the Ae3

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.633 ◽

2018 ◽

Vol 941 ◽

pp. 633-638

Author(s):

John Joseph Jonas ◽

Clodualdo Aranas Jr. ◽

Samuel F. Rodrigues

Keyword(s):

Electron Microscopy ◽

Driving Force ◽

Energy Difference ◽

Accelerated Cooling ◽

Free Energy Difference ◽

Dynamic Transformation ◽

Plate Rolling ◽

Temperature Transformation ◽

Mn Steel ◽

Kinetics Of

Under loading above the Ae3 temperature, austenite transforms displacively into Widmanstätten ferrite. Here the driving force for transformation is the net softening during the phase change while the obstacle consists of the free energy difference between austenite and ferrite as well as the work of shear accommodation and dilatation during the transformation. Once the driving force is higher than the obstacle, phase transformation occurs. This phenomenon was explored here by means of the optical and electron microscopy of a C-Mn steel deformed above their transformation temperatures. Strain-temperature-transformation (STT) curves are presented that accurately quantify the amount of dynamically formed ferrite; the kinetics of retransformation are also specified in the form of appropriate TTRT diagrams. This technique can be used to improve the models for transformation on accelerated cooling in strip and plate rolling.

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Niobium Microalloyed Line Pipe Steels: Technological Overview

ASME 2013 India Oil and Gas Pipeline Conference ◽

10.1115/iogpc2013-9828 ◽

2013 ◽

Cited By ~ 1

Author(s):

J. M. Gray ◽

S. V. Subramanian

Keyword(s):

Process Integration ◽

Target Strength ◽

Accelerated Cooling ◽

Pipe Steels ◽

Line Pipe ◽

Steel Technology ◽

Quantitative Understanding ◽

Line Pipe Steel ◽

Low Levels ◽

Evolution Of Microstructure

A quantitative understanding of hierarchical evolution of microstructure is essential in order to design the base chemistry and optimize rolling schedules to obtain the morphological microstructure coupled with high density and dispersion of crystallographic high angle boundaries to achieve the target strength and fracture properties in higher grade line pipe steels, microalloyed with niobium. Product-process integration has been the key concept underlying the development of niobium microalloyed line pipe steel technology over the years. The development of HTP technology based on 0.1 wt % Nb and low interstitial was predicated by advances in process metallurgy to control interstitial elements to low levels (C <0.03wt% and N< 0.003wt%), sulfur to ultra-low levels (S<20ppm), as well as in product metallurgy based on advances in basic science aspects of thermo-mechanical rolling and phase transformation of pancaked austenite under accelerated cooling conditions, and toughness properties of heat affected zones in welding of niobium microalloyed line pipes. A historical perspective/technological overview of evolution of HTP for line pipe applications is the focus of this paper in order to highlight the key metallurgical concepts underlying Nb microalloying technology which have paved the way for successful development of higher grade line pipe steels over the years.

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Welding thermal cycle-triggered precipitation processes in steel S700MC subjected to the thermo-mechanical control processing

Archives of Metallurgy and Materials ◽

10.1515/amm-2017-0048 ◽

2017 ◽

Vol 62 (1) ◽

pp. 321-326 ◽

Cited By ~ 13

Author(s):

J. Górka

Keyword(s):

Thermomechanical Processing ◽

Control Process ◽

Base Material ◽

Structural Defects ◽

Accelerated Cooling ◽

Internal Stresses ◽

Mechanical Control ◽

Thin Foils ◽

Precipitation Processes ◽

The Matrix

Abstract This study presents tests concerned with welding thermal process-induced precipitation processes taking place in 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP) with accelerated cooling. The thermomechanical processing of steel S700MC leads to its refinement, structural defects and solutioning with hardening constituents. Tests of thin foils performed using a transmission electron microscope revealed that the hardening of steel S700MC was primarily caused by dispersive (Ti,Nb)(C,N) precipitates (being between several and less than twenty nanometers in size). In arc welding, depending on a welding method and linear energy, an increase in the base material in the weld is accompanied by the increased concentration of hardening microagents in the weld. The longer the time when the base material remains in the liquid state, the greater the amount of microagents dissolved in the matrix. During cooling, such microagents can precipitate again or remain in the solution. An increase in welding linear energy is accompanied by an increase in the content of hardening phases dissolved in the matrix and, during cooling, by their another uncontrolled precipitation in the form of numerous fine-dispersive (Ti,Nb)(C,N) precipitates of several nm in size, leading to a dislocation density increase triggered by type 2 internal stresses.

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Justification for Reducing In-Service Weld Inspection Delay Times for Liquid Pipelines

Volume 3: Operations, Monitoring, and Maintenance; Materials and Joining ◽

10.1115/ipc2018-78250 ◽

2018 ◽

Author(s):

Matt Boring ◽

Mike Bongiovi ◽

David Warman ◽

Harold Kleeman

Keyword(s):

Hydrogen Concentration ◽

Delay Time ◽

Time Dependent ◽

Accelerated Cooling ◽

Hydrogen Cracking ◽

Inspection Method ◽

Time To Peak ◽

Preventative Measures ◽

Increased Risk ◽

Delay Times

Welds that are made onto an operating pipeline cool at an accelerated rate as a result of the flowing pipeline contents cooling the weld region. The accelerated cooling rates increase the probability of forming a crack-susceptible microstructure in the heat-affected zone (HAZ) of in-service welds. The increased risk of forming such microstructures makes in-service welds more susceptible to hydrogen cracking compared to welds that do not experience accelerated cooling. It is understood within the pipeline industry that hydrogen cracking is a time-dependent failure mechanism. Due to the time-dependent nature and susceptibility of in-service welds to hydrogen cracking, it is common to delay the final inspection of in-service welds. The intent of the delayed inspection is to allow hydrogen cracks, if they were going to occur, to form so that the inspection method could detect them and the cracks could repaired. Many industry codes provide a single inspection delay time. By providing a single inspection delay time it is implied that the inspection delay time should be applied for all situations independent of the welding conditions or any other preventative measures the company may employee. There are many aspects that should be addressed when determining what should be considered an appropriate inspection delay time and these aspects can vary the inspection delay time considerably. Such factors include the cooling characteristics of the operating pipeline, the welding procedure that is being followed, the chemical composition of the material being welded and if any preventative measures such as post-weld heating are applied. The objective of this work was to provide an engineering justification for realistic minimum inspection delay times for different in-service welding scenarios. The minimum inspection delay time that was determined was based on modelling results from a previously developed two-dimensional hydrogen diffusion model that predicts the time to peak hydrogen concentration at any location within a weld HAZ. The time to peak hydrogen concentration was considered equal to the minimum inspection delay time since the model uses the assumption that if a weld was to crack the cracking would occur prior to or at the time of peak hydrogen concentration. Several factors were varied during the computer model runs to determine the effect they had on the time to peak hydrogen concentration. These factors included different welding procedures, different material thicknesses and different post-weld heating temperatures. The post-weld heating temperatures were varied between 40 F (4 C) and 300 F (149 C). The results of the analysis did provide justification for reducing the inspection delay time to 30 minutes or less depending on the post-weld heating temperature and pipeline wall thickness. This reduction in inspection delay time has the potential to significantly increase productivity and reduce associated costs without increasing the associated risk to pipeline integrity or public safety.

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Adaptive Control of Accelerated Cooling Plant Based on Distributed Observer

IFAC Proceedings Volumes ◽

10.1016/s1474-6670(17)49199-3 ◽

1993 ◽

Vol 26 (2) ◽

pp. 611-614

Author(s):

V.I. Utkin ◽

I.M. Kaliko ◽

G. Bartolini ◽

C. Ghiazza

Keyword(s):

Adaptive Control ◽

Accelerated Cooling

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