Mean-flow-stress analysis of laboratory hot-rolled S1100QL steel with minor Nb addition

Foder, Jan; Klančnik, Grega; Burja, Jaka; Kokalj, S.; Bradaškja, Boštjan

doi:10.17222/mit.2020.125

Cited by 2 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Like in our previous study on ultrahigh-strength steel (UHSS) [18], the hot deformation behavior of C-Mn steel was also studied during successive reductions and evaluated by MFS as presented further in the paper. The focus is given not only on the roughing stage but also on the finish rolling stage where strain-induced precipitation is expected (for 240 Nb) in partly recrystallized austenite [18].…”

Section: Methodsmentioning

confidence: 99%

“…The general composition, presented in Table 1, was determined by optical emission spectroscopy, ARL MA-310. Carbon and sulfur were determined as in [18] by combustion method using LECO CS-600 (CS 600 series, LECO Corporation, St. Joseph, Michigan, MI, USA) and nitrogen by LECO TC-500 (TC 500, RO 500, TN 500 series, LECO Corporation,St. Joseph, Michigan, MI, USA).…”

Section: Methodsmentioning

confidence: 99%

“…Material resistance during hot rolling can be measured by an indirect method using calculated mean flow stress (MFS) from measured vertical rolling force (FR) as shown in the previous study [18] based on the simplified Sims model [19] and used in numbers of papers [20,21]. Observation of MFS elucidates the material softening and strain hardening phenomena in processed C-Mn steel based on rolling schedules and chemical compositions.…”

Section: Finishing Stagementioning

confidence: 99%

“…Based on [18,23], three basic recrystallization-deformation behaviors are recognized: static recrystallization (Type I); unwanted partial recrystallization (Type III) defined between RST and RLT (due to interaction of austenite continuous grain growth, pinning of PAG, and nucleation of new dislocation free grains), or simply the region of T nr ; and region of no recrystallization, below RST or T nr (Type II). All deformation behaviors are listed in Figure 5a.…”

Section: Mean-flow Stress Curvesmentioning

confidence: 99%

See 3 more Smart Citations

Hot Deformation Behavior of C-Mn Steel with Incomplete Recrystallization during Roughing Phase with and without Nb Addition

Klančnik¹,

Foder

Bradaškja

et al. 2022

Metals

View full text Add to dashboard Cite

The objective of the study is to improve understanding of the practical role of niobium (Nb) in the case of industrial inconsistent rolling processes such as the rolling of heavy gauge plates where a lower stored energy rolling practice will result in a less stable and less repeatable static recrystallization (SRX) activation that prevents complete recrystallization. In the current study, these variabilities are validated by comparing the mean flow stress (MFS) indirectly determined from the rolling force measured on a reverse four-high rolling mill stand. The material resistance to deformation and grain size evolution of a C-Mn steel during hot rolling was observed and validated with and without Nb addition. The pre-defined rolling schedule was predicted to exhibit incomplete recrystallization in the roughing phase due to the limited stored energy of deformation that resulted from low rolling loads and a higher number of rolling passes. The prior austenite grain size (PAGS) distribution was predicted and compared to the measured effective ferrite grain (FG) size distribution after the completion of hot rolling and phase transformation achieved using natural air plate cooling. Both the predicted PAG and measured FG distributions revealed the presence of multimodality, and both distributions were used for grain size reduction factor determination for γ → α transformation for the current study with 1.96 for 0 Nb and 1.70 for 240 Nb. The results presented in this paper are not only limited to the rolling schedule used in this paper because instabilities resulting in incomplete austenite conditioning are also observed when evaluating the cross-sections of other heavy plates and various steel grades utilizing different processing routes with comparable compositions such as modern lean abrasion-resistant steels, regular line pipe steels, and other similar grades.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Finishing Stagementioning

confidence: 99%

Section: Mean-flow Stress Curvesmentioning

confidence: 99%

See 2 more Smart Citations

Hot Deformation Behavior of C-Mn Steel with Incomplete Recrystallization during Roughing Phase with and without Nb Addition

Klančnik¹,

Foder

Bradaškja

et al. 2022

Metals

View full text Add to dashboard Cite

show abstract

“…The Nb, V-Nb, and Ti-Nb were finished rolled using 49%, 42%, and 58% of final reduction below the T nr . Detailed analysis of laboratory hot rolling, temperature control, and percentage of final reduction of Ti-Nb S1100QL steel can be found in [28]. The last step in the production process was off-line laboratory heat treatment in an electric furnace, using additional type-K thermocouples for temperature control.…”

Section: Methodsmentioning

confidence: 99%

Grain Size Evolution and Mechanical Properties of Nb, V–Nb, and Ti–Nb Boron Type S1100QL Steels

Foder

Burja

Klančnik³

2021

Metals

View full text Add to dashboard Cite

Titanium additions are often used for boron factor and primary austenite grain size control in boron high- and ultra-high-strength alloys. Due to the risk of formation of coarse TiN during solidification the addition of titanium is limited in respect to nitrogen. The risk of coarse nitrides working as non-metallic inclusions formed in the last solidification front can degrade fatigue properties and weldability of the final product. In the presented study three microalloying systems with minor additions were tested, two without any titanium addition, to evaluate grain size evolution and mechanical properties with pre-defined as-cast, hot forging, hot rolling, and off-line heat-treatment strategy to meet demands for S1100QL steel. Microstructure evolution from hot-forged to final martensitic microstructure was observed, continuous cooling transformation diagrams of non-deformed austenite were constructed for off-line heat treatment, and the mechanical properties of Nb and V–Nb were compared to Ti–Nb microalloying system with a limited titanium addition. Using the parameters in the laboratory environment all three micro-alloying systems can provide needed mechanical properties, especially the Ti–Nb system can be successfully replaced with V–Nb having the highest response in tensile properties and still obtaining satisfying toughness of 27 J at –40 °C using Charpy V-notch samples.

show abstract

Mean-flow-stress analysis of laboratory hot-rolled S1100QL steel with minor Nb addition

Cited by 2 publications

References 0 publications

Hot Deformation Behavior of C-Mn Steel with Incomplete Recrystallization during Roughing Phase with and without Nb Addition

Hot Deformation Behavior of C-Mn Steel with Incomplete Recrystallization during Roughing Phase with and without Nb Addition

Grain Size Evolution and Mechanical Properties of Nb, V–Nb, and Ti–Nb Boron Type S1100QL Steels

Contact Info

Product

Resources

About