Investigating the Properties of Coil Tail in Ti–Nb–Mo Microalloyed Hot‐Rolled Strip

Xiong

et al. 2020

Mater. Res. Express

Self Cite

The heat treatments with different quenching and tempering temperatures were conducted to clarify the effects of Q&T (quenching and tempering) parameters on phase transformation, microstructure, precipitation, mechanical properties in a PS-30Cr2Nb pipeline steel. Results indicate that the optimum property of tensile strength of 892 MPa and elongation of 19.17% was obtained at a low quenching (950°C) and low tempering temperature (570°C). Finer prior austenite grains and carbides contributed to the higher strength. Besides, the content of coarsening carbides increased with tempering temperature and quenching temperature. The increased content of coarsening carbides is responsible for the deteriorative comprehensive performance. In addition, Fe 3 C particle was gradually substituted by the alloy carbides with the proceeding of tempering by the dynamic assignment of elements.

Section: Methodsmentioning

confidence: 99%

Section: Mechanical Propertiesmentioning

confidence: 99%

Effects of Q&T parameters on phase transformation, microstructure, precipitation and mechanical properties in a PS-30Cr2Nb pipeline steel

Guan

Xiong

et al. 2020

Mater. Res. Express

Self Cite

“…Moreover, an appropriate amount of Mo can facilitate the formation of nanoscale Ti precipitates. [25,26]…”

Section: Composition Designmentioning

confidence: 99%

“…The detailed descriptions of sample preparations are presented in the literature. [10][11][12]25,27] 3. Results…”

Section: Microstructuresmentioning

confidence: 99%

“…It is well known that the lath martensite consists of three MAIN substructures such as packet, block, and lath, and the grain size in TM usually refers to the size of block in the martensite. [25] It is important to obtain the size of martensite block in the direct comparison between martensite dimensions. During the measurement, martensite block at the edge (almost 226 and 190 grains) was excluded to ensure the accuracy of the obtained results, and the actual block numbers for the Q850 and Q910 steels were 3420 and 2932, respectively.…”

Section: Microstructurementioning

confidence: 99%

See 1 more Smart Citation

Influences of Quenching Temperature on the Microstructure Evolution and Strength−Toughness of a Novel Medium‐Carbon Ti−Mo‐Bearing Martensite Steel

Guan

Yuan³

et al. 2021

steel research int.

Self Cite

High-strength steels have attracted much attention in recent decades due to their positive roles in energy conservation, emission reduction, and cost reduction in the global setting. [1,2] Numerous methods have been adopted to improve the strength of steels. For example, microalloyed steels, individually or associatedly alloyed with Nb, V, and Ti, manifest better mechanical properties than other plain carbon steels. [3][4][5] The super-bainite steel proposed by Bhadeshia and coworkers [6,7] exhibits commendable properties due to the presence of nanoscale bainite structure and retained austenite. In addition, numerous works have been conducted on ultrafine-grain (UFG) steels consisting of microÀnanometer ferrite/austenite grains. [8][9][10][11][12][13][14] Especially, martensite steels are found to be promising due to their very high strength; however, the unsatisfactory toughness limits their commercial applications. [15,16] To improve the properties of martensite steels, secondary-hardening martensite steel, maraging steel, medium-carbon low-alloy martensite steel, and bainite/martensite duplex-phase high-strength steels have been successively proposed. [17][18][19][20][21][22][23][24] Kown et al. [17] prepared a new type of secondary-hardening martensite steel (0.24CÀ3.13WÀ3.07CrÀ14.18CoÀ9.83Ni) with a hardness of 55 HRC and room-temperature impact energy of <30 J. Mooney et al. [18] and Casalino et al. [19] both developed maraging steels with different Ti additions. The tensile strength was substantially improved to about 1200 MPa accomplished by a common failure elongation. Liu and coworkers [20] fabricated a novel ultrahigh-strength martensite steel with a strength of 1589À2446 MPa by quenching and tempering; however, the increased strength sacrificed the ductility of the steel. Multifarious schemes have been adopted to improve the toughness of martensite steels; unfortunately, the improvement of toughness is often accompanied by the sacrifice in strength.Very few studies reported the improved mechanical properties of medium-carbon martensite steel by simultaneous addition of Ti and Mo. In the present study, a novel TiÀMo-bearing martensite steel was developed by thermoÀmechanical control process (TMCP) and subsequent quenching and tempering (QÀT) process to optimize the strength and toughness of high-strength martensite steels. It is well known that the design of quenching temperature is crucial for the final service life of the low-alloy high-strength steels compared with isothermal holding time. A lower quenching temperature will result in an incomplete austenization for the martensite steel, whereas a higher quenching temperature leads to coarse austenite grains and deteriorates the combination property of the high-strength TiÀMo-bearing

Enhanced Thermal Stability of the Low‐Carbon Ultrafine Grain Steel with Nanoprecipitates

Zhang

Wang

et al. 2021

steel research int.

Self Cite

Niobium (Nb), a microalloy element, is purposefully added to improve the thermal stability of ferrite grains in a low-carbon ultrafine grain (UFG) steel. Results manifest the excellent thermal stability in the Nb-UFG steel with 0.028 wt% Nb addition by providing favorable kinetics and thermodynamic stabilization effects. The almost unchanged grain size and mechanical properties of Nb-UFG steels annealed for 45 and 180 min at 500 C are simultaneously obtained by the heterogeneous ferrite grains, NbC precipitates, and geometrically necessary dislocations (GNDs) mainly formed during tensile tests. The imperceptible change in size and volume fraction of NbC particles of the two Nb-UFG steels annealed at different time are attributed to the inherent thermal stability of NbC and main precipitation pattern of NbC particles from the α phase.