Shaping mechanism of ultrafine metastable austenite in HSLA steels through a cumulative process of hot rolling, partitioning and tempering

2021 ◽  
Vol 811 ◽  
pp. 141060
Author(s):  
Shilong Liu ◽  
Bin Hu ◽  
Yishuang Yu ◽  
Chengjia Shang ◽  
R.D.K. Misra ◽  
...  
1982 ◽  
Vol 104 (1) ◽  
pp. 47-52 ◽  
Author(s):  
A. Murthy ◽  
J. G. Lenard

The accuracy and precision of four mathematial models of varying complexity are evaluated by comparing their predictions to experimental data generated in carefully controlled laboratory experiments and to production logs obtained from the finishing trains of several Canadian, American, and European hot strip mills. The materials rolled are low carbon and HSLA steels; the models used are Orowan’s formulation with Shida’s flow strength and Ford and Alexander’s formulation with Shida’s flow strength; then both these formulations are combined with Ekelund’s flow strength equation. It is concluded that Orowan’s formulation with Shida’s flow strength relation is the most consistently accurate technique of analysis. Further, the behavior of HSLA steels is not well described by either Shida’s or Ekelund’s equations.


2007 ◽  
Vol 539-543 ◽  
pp. 28-35 ◽  
Author(s):  
Anthony J. DeArdo ◽  
R. Marraccini ◽  
Ming Jian Hua ◽  
C. Isaac Garcia

There are two obstacles to be overcome in the CSP production of HSLA heavy gauge strip and skelp, especially for API Pipe applications. First, the microalloying should be conserved by eliminating the high temperature precipitation of complex particles. Second, the heterogeneous microstructure that normally results from the 800 micron initial austenite in the 50mm slab as it is rolled to 12.5mm skelp must be eliminated to optimize the final microstructure and improve the final mechanical properties. Alteration in the hot rolling sequence can strongly homogenize the final austenite and resulting final ferritic microstructure. When coupled with a low coiling temperature near 550°C, the new rolling practice can result in Nb HSLA steels that can easily meet requirements for strength, toughness and ultrasonic testing in 12.5mm skelp gauges for X70 API pipe applications. The underlying physical metallurgy of these two breakthroughs will be presented and discussed in detail.


2019 ◽  
Vol 391 ◽  
pp. 120-127
Author(s):  
J. Prakash Gautam ◽  
A. Miroux ◽  
Jaap Moerman ◽  
Leo Kestens

No recrystallization of austenite, Tnr, has an important influence on the transformed phase fractions and the final crystallographic texture after hot deformation. This paper investigates the evolution of microstructure and texture components during hot-rolling in two austenitic region based on Tnr along with three different cooling trajectory and coiling in dual-phase steels and high strength low alloys steel. The recrystallization of the austenite, the austenite deformation followed by the austenite-to-ferrite transformation influence the final microstructure and texture in dual phase steels, have been examined by means of optical microscopy, X-ray diffraction (XRD) measurements. Recrystallized and deformed austenite have clearly different texture components and, due to the specific lattice correspondence relations between the parent austenite phase and its transformation products, the resulting ferrite textures are different as well.


Author(s):  
Mengzhe Chen ◽  
Siqin Wang ◽  
Jun Ke

A series of investigations have been conducted into the nature and origin of the dislocation cell structure. R.J.Klassen calculated that the dislocation cell limiting size in pure ferrite matrix is about 0.4 μm. M.N.Bassion estimated the size of dislocation cell in deformed ferrite of HSLA steels to be of the same order.In this paper, TEM observation has been concentrated on the interaction of fine carbide precipitates with dislocation cell structure in deformed Fe-C-V (0.05%C, 0.13% and 0.57%V) and Fe-C-Nb (0.07 %C and 0.04%Nb) alloys and compared with that in Fe-C (0.05%). Specimens were austenitized at 1500 “C/20 min and followed by isothermal treatment at 750 °C and 800 “C for 20, 40 and 120 minutes . The carbide particle sizes in these steels are from 9 to 86nm measured from carbon extraction replicas. Specimens for TEM were cut from differently deformed areas of tensile specimens deformed at room temperture. The thin foils were jet electropolished at -20 C in a solution of 10% perchloric acid and 90% ethanol. The TEM observation was carried out in JEM 100CX , EM420 at 100kv and JEM 2000FX at 200kv.


Author(s):  
E. N. Shiryaeva ◽  
M. A. Polyakov ◽  
D. V. Terent'ev

Complexity of modern metallurgical plants, presence of great number of horizontal and vertical interactions between their various structural subdivisions makes it necessary to apply a systems analysis to elaborate effective measures for stable development of a plant operation. Among such measures, digitalization of a plant is widespread at present. To implement the digitalization it is necessary to have clear vision about links at all the levels of the technological system of a plant. A terminology quoted, accepted in the existing regulatory documents for defining of conceptions, comprising the technological system. It was shown, that the following four hierarchical levels of technological systems are distinguished: technological systems of operations, technological systems of processes, technological systems of production subdivisions and technological systems of plants. A hierarchical scheme of technological systems of hot-rolled sheet production at an integrated steel plant presented. Existing horizontal and vertical links between the basic plant’s shops shown. Peculiarities of flows of material, energy and information at the operation “rolling” of the technological system “hot rolling of a steel sheet” considered. As a technical system of the technological process of the hot rolling, the hot rolling mill was chosen. A structural diagram of the hot rolling mill was elaborated, the mill being consisted of reheating furnaces, roughing and finishing stand groups, with an intermediate roll-table between them, and down-coilers section. Since the rolling stands are the basic structural elements of the hot rolling mill, structural diagrams of a roughing and a finishing stands were elaborated. Results of the systems analysis of the technological and technical systems, hierarchically linked in the process of steel sheet hot rolling, can be applied for perfection of organization structure of the whole plant, as well as for elaboration mathematical models of a system separate elements functioning, which is a necessary condition for a plant digitalization.


2019 ◽  
Vol 61 (5) ◽  
pp. 397-404
Author(s):  
Vyacheslav Goryany ◽  
Olga Myronova ◽  
Johannes Buch ◽  
Alexander Buch ◽  
Frank Stein

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