Hot Deformation Behavior and Dynamic Recrystallization of Ultra High Strength Steel

Zhong, Liping; Wang, Bo; Hu, Chundong; Zhang, Jieyu; Yao, Yu

doi:10.3390/met11081239

Cited by 7 publications

(5 citation statements)

References 18 publications

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“…The micro graph presented by Fig. 4 contains fine lath martensite colonies arranged parallel to the forging direction, while the elongated white regions are surrounding the outside borders of the martensite colonies [17].…”

Section: Resultsmentioning

confidence: 99%

Characterization of Hot Deformation behavior for Ultra-High Strength (UHS) Steel containing Tungsten

El-Bitar,

ElMeligy,

Borek

et al. 2023

Acta Metall Slovaca

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The steel alloy of the current study contains 0.3% carbon with different amounts of Cr, and Mo, in addition to W. Single simulation hits were designed as isothermal passes for compressive hot deformation up to 0.5 true strain. Each simulation compressive pass was carried out at temperatures, 1050, 950, 850 and 750 oC, with strain rates 0.1 and 1.0 sec-1. A numerical computational model is used for formulation of the alloy hot flow behavior at the specified conditions. The model considers inseparable strain hardening mechanism and dynamic softening phenomenon. It is noticed that high deformation temperature lowers the flow stress value (σf), while the increase of the strain rate raises it. The flow curves reveal initial high strain hardening phenomena in combination with low dynamic softening features. With the increase of strain, the dynamic softening, becomes dominant, and the flow stress gradually drops until a relatively stable stress level. Predicted flow curves were then constructed and compared with their counterpart experimental flow curves. The predicted flow curves are typically matching the counterpart experimental ones.

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Section: Resultsmentioning

confidence: 99%

Characterization of Hot Deformation behavior for Ultra-High Strength (UHS) Steel containing Tungsten

El-Bitar,

ElMeligy,

Borek

et al. 2023

Acta Metall Slovaca

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“…In the literature [24][25][26][27][28][29][30], one can encounter two-step curves describing the growth of the fraction of the softened structure as a function of the thermodynamic conditions of the forming process, i.e., temperature, strain, strain rate and grain size, during the interpass time. The most complete data set represents the work of authors around Medina [27][28][29][30][31][32][33][34][35][36][37]. The data of these authors were used in the modification of our model.…”

Section: Description Of the Microstructure Development Model Modifica...mentioning

confidence: 99%

Analysis of the Microstructure Development of Nb-Microalloyed Steel during Rolling on a Heavy-Section Mill

Sauer

Fabík²,

Schindler

et al. 2022

Materials

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It is not realistic to optimize the roll pass design of profile rolling mills, which typically roll hundreds of profiles, using physical modelling or operational rolling. The use of reliable models of microstructure evolution is preferable here. Based on the mathematical equations describing the microstructure evolution during hot rolling, a modified microstructure evolution model was presented that better accounts for the influence of strain-induced precipitation (SIP) on the kinetics of static recrystallization. The time required for half of the structure to soften, t0.5, by static recrystallization was calculated separately for both situations in which strain-induced precipitation occurred or did not occur. On this basis, the resulting model was more sensitive to the description of grain coarsening in the high-rolling-temperature region, which is a consequence of the rapid progress of static recrystallization and the larger interpass times during rolling on cross-country and continuous mills. The modified model was verified using a plain strain compression test (PSCT) simulation of rolling a 100-mm-diameter round bar performed on the Hydrawedge II hot deformation simulator (HDS-20). Four variants of simulations were performed, differing in the rolling temperature in the last four passes. For comparison with the outputs of the modified model, an analysis of the austenite grain size after rolling was performed using optical metallography. For indirect comparison with the model outputs, the SIP initiation time was determined based on the NbX precipitate size distribution obtained by TEM. Using the PSCT and the outputs from the modified microstructure evolution model, it was found that during conventional rolling, strain-induced precipitation occurs after the last pass and thus does not affect the austenite grain size. By lowering the rolling temperature, it was possible to reduce the grain size by up to 56 μm, while increasing the mean flow stress by a maximum of 74%. The resulting grain size for all four modes was consistent with the operating results.

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“…The strength, hardness, and toughness of the new ultra-high-strength steel produced has significantly improved since the continuous improvement of steel smelting and since rolling technology was introduced. In fields such as aerospace, national defense, and shipbuilding, they are slowly taking the place of traditional high-strength steel and becoming a vital critical material [1][2][3]. The balance between strength and toughness becomes more challenging for steels with higher strength [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Ultrasonic Treatment on Microstructure and Properties of 2000 MPa Ultra-High-Strength Steel-Welded Joints

Chu,

Wang,

Yuan

et al. 2023

Coatings

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The microstructure and mechanical properties of ultra-high-strength steel weld joints were examined for the effect of ultrasonic treatment. ER120S-G welding wire is necessary for welding 4 mm thick ultra-high-strength steel. After that, the weld toe region underwent different parameters of the ultrasonic stress relief process. As a means of surface treatment for weld seams, noticeable grain refinement and the formation of a fine-grained layer were observed in the weld toe region after ultrasonic treatment. The blind hole method was used to measure residual stresses in the weld seam, which indicated a transition from tensile stress to compressive stress in the treated portion of the joint. Different ultrasonic treatment processes resulted in a significant increase in hardness values near the weld toe region during hardness testing. The hardness of the weld joint that was treated with ultrasound increased initially but then stabilized after increasing the frequency. The ultrasound-treated joints showed a significant improvement in both tensile strength and fracture elongation, as demonstrated in the tensile tests.

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Hot Deformation Behavior and Dynamic Recrystallization of Ultra High Strength Steel

Cited by 7 publications

References 18 publications

Characterization of Hot Deformation behavior for Ultra-High Strength (UHS) Steel containing Tungsten

Characterization of Hot Deformation behavior for Ultra-High Strength (UHS) Steel containing Tungsten

Analysis of the Microstructure Development of Nb-Microalloyed Steel during Rolling on a Heavy-Section Mill

Effect of Ultrasonic Treatment on Microstructure and Properties of 2000 MPa Ultra-High-Strength Steel-Welded Joints

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