Effect of Thermomechanical Processing on the Microstructure and Mechanical Properties of Nb-Ti-V Microalloyed Steel

Opiela, M.

doi:10.1007/s11665-014-1111-8

Cited by 50 publications

(29 citation statements)

References 12 publications

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“…Welding can disturb the processes mentioned above and lead to the uncontrolled precipitation of type MX phases. In addition, an excessively high nitrogen content in the base material combined with an overly low content of elements (aluminium and, particularly, titanium) bonding free nitrogen, may be responsible for the phenomenon of ageing responsible for the deteriorated weldability of steels [1][2][3][4][5][6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

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

Górka¹

2017

Archives of Metallurgy and Materials

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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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Section: Introductionmentioning

confidence: 99%

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

Górka¹

2017

Archives of Metallurgy and Materials

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“…1 Also for yield points above 550 MPa, steels subjected to thermomechanical rolling with accelerated cooling and tempering are characterised by a lower carbon equivalent than toughened steels. [2][3][4][5] Due to the significantly lower carbon equivalent, thermomechanicaly treated steels should have significantly better weldability in comparison to normalised or toughened steels of a similar yield point. The alloying microagents of S700MC steel, i.e.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and properties of the high-temperature (HAZ) of thermo-mechanically treated S700MC high-yield-strength steel

Górka

2016

Mater. Tehnol.

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The aim of the study was to determine the properties and microstructure of the high-temperature heat affected zone (HAZ) of S700MC steel heated to a temperature of 1250°C and cooled at different speeds. The simulation of the thermal cycles was performed using a welding thermal cycles simulator. Samples with a cross-section 10 mm × 10 mm × 55 mm were submitted to metallographic analysis, impact tests, hardness measurements and tensile tests. Welding thermal cycles with cooling times t8/5 = (3, 5, 10, 15, 30, 60 and 120) s and a maximum temperature cycle temperature of Tmax = 1250°C were used. The welding thermal thermomechanical processing cycles differ significantly, especially with high rates of heating and cooling in the SWC, short time holding at the maximum temperature and frequent overlap of two or more cycles during the multi-layer welding. One of the elements in the evaluation of steel weldability is the analysis of the austenite phase transformation during cooling. Steel hardness tests on simulated HAZ regions cooling times increasing from 3 s to 120 s, showed reductions by approximately 40 HV, while, regardless of the length of the cooling time t8/5, the impact resistance was very low, at the level of a few J/cm 2 . The tensile strength, hardness and toughness indicates a secondary role of austenite in the control of welded joints transformation strength and plastic properties, the analysis of the g-a phase transition not shown to be a reliable basis for assessment of the weldability of this steel group. Keywords: TMCP steel, welding thermal cycles, HAZ, high yield strength, impact resistance Namen {tudije je bil dolo~iti lastnosti in mikrostrukturo visokotemperaturne toplotno vplivanega obmo~ja zvara (HAZ) v jeklu S700MC, segretem na temperaturo 1250°C in ohlajenem pri razli~nih hitrostih. Simulacija procesa toplotnih ciklov je bila izvedena z uporabo simulatorja toplotnih ciklov pri varjenju. Vzorci s presekom 10 mm × 10 mm × 55 mm so bili metalografsko pregledani, izveden je bil udarni preizkus, izmerjena je bila trdota in izvedeni so bili natezni preizkusi. Uporabljeni so bili toplotni cikli pri varjenju s~asi ohlajanja t8/5 = (3, 5, 10, 15, 30, 60 in 120) s in maksimalna temperatura toplotnega cikla je bila Tmax = 1250°C. Pri varjenju se cikli varilno termi~nega in termomehanskega procesiranja precej razlikujejo, predvsem pri veliki hitrosti ogrevanja in ohlajanja v SWC, kratkotrajnem zadr`anju na maksimalni temperaturi in pogostem prekrivanju enega ali ve~ciklov pri ve~plastnih zvarih. Eden od elementov pri ocenjevanju varivosti jekla, je analiza premene avstenita med ohlajanjem. Pri preizkusih trdote simuliranih HAZ podro~ij, se le ta, s pove~anjem~asa ohlajanja od 3 s na 120 s, zmanj{a za okrog 40 HV, medtem ko je`ilavost zelo nizka in na nivoju nekaj J/cm 2 ne glede na~as ohlajanja t8/5. Natezna trdnost, trdota iǹ ilavost ka`ejo drugotno vlogo pri kontroli trdnosti in plasti~nosti transformiranega avstenita zvarjenih spojev. Analiza faznega prehoda g-a ni zanesljiva osnova za ugotavljanje varlj...

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“…Physical simulation [10,17,[22][23][24][25] and numerical modelling [26][27][28][29] are the effective ways of determining the force-energetic parameters and microstructure evolution during thermomechanical processing. The hot-working behaviour is rarely investigated using semi-industrial hot-rolling lines [9,30,31] or on the basis of real industrial rolling trials [26,32].…”

Section: Introductionmentioning

confidence: 99%

Non-Metallic Inclusions and Hot-Working Behaviour of Advanced High-Strength Medium-Mn Steels

Grajcar¹,

Woźniak²,

Kozłowska³

2016

Archives of Metallurgy and Materials

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The work addresses the production of medium-Mn steels with an increased Al content. The special attention is focused on the identification of non-metallic inclusions and their modification using rare earth elements. The conditions of the thermomechanical treatment using the metallurgical Gleeble simulator and the semi-industrial hot rolling line were designed for steels containing 3 and 5% Mn. Hot-working conditions and controlled cooling strategies with the isothermal holding of steel at 400°C were selected. The effect of Mn content on the hot-working behaviour and microstructure of steel was addressed. The force-energetic parameters of hot rolling were determined. The identification of structural constituents was performed using light microscopy and scanning electron microscopy methods. The addition of rare earth elements led to the total modification of non-metallic inclusions, i.e., they replaced Mn and Al forming complex oxysulphides. The Mn content in a range between 3 and 5% does not affect the inclusion type and the hot-working behaviour. In contrast, it was found that Mn has a significant effect on a microstructure.

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Effect of Thermomechanical Processing on the Microstructure and Mechanical Properties of Nb-Ti-V Microalloyed Steel

Cited by 50 publications

References 12 publications

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

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

Microstructure and properties of the high-temperature (HAZ) of thermo-mechanically treated S700MC high-yield-strength steel

Non-Metallic Inclusions and Hot-Working Behaviour of Advanced High-Strength Medium-Mn Steels

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