Effect of Elevated Deformation Temperatures on Microstructural and Tensile Behavior of Si-Al Alloyed TRIP-Aided Steel

Kozłowska, Aleksandra; Grajcar, A.

doi:10.3390/ma13225284

Cited by 5 publications

(3 citation statements)

References 38 publications

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“…However, new martensite blocks the dislocation movement and affects the work hardening [48]. In addition, the same results were reported by Kozłowska and Grajcar for a hot-rolled Si-Al-alloyed 0.24C-1.5Mn-0.87Si in which there was found an increment of work-hardening exponent with the gradual transformation of retained austenite into martensite [49]. On the other hand, the increment in the n-exponent found in QP-421 can be explained by the austenite's transformation into martensite during the deformation.…”

Section: Microstructural Characterization After the Qp Processsupporting

confidence: 83%

Heat Treatment Design for a QP Steel: Effect of Partitioning Temperature

Carpio

Calvo

García³

et al. 2021

Metals

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Designing a new family of advanced high-strength steels (AHSSs) to develop automotive parts that cover early industry needs is the aim of many investigations. One of the candidates in the 3rd family of AHSS are the quenching and partitioning (QP) steels. These steels display an excellent relationship between strength and formability, making them able to fulfill the requirements of safety, while reducing automobile weight to enhance the performance during service. The main attribute of QP steels is the TRIP effect that retained austenite possesses, which allows a significant energy absorption during deformation. The present study is focused on evaluating some process parameters, especially the partitioning temperature, in the microstructures and mechanical properties attained during a QP process. An experimental steel (0.2C-3.5Mn-1.5Si (wt%)) was selected and heated according to the theoretical optimum quenching temperature. For this purpose, heat treatments in a quenching dilatometry and further microstructural and mechanical characterization were carried out by SEM, XRD, EBSD, and hardness and tensile tests, respectively. The samples showed a significant increment in the retained austenite at an increasing partitioning temperature, but with strong penalization on the final ductility due to the large amount of fresh martensite obtained as well.

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Section: Microstructural Characterization After the Qp Processsupporting

confidence: 83%

Heat Treatment Design for a QP Steel: Effect of Partitioning Temperature

Carpio

Calvo

García³

et al. 2021

Metals

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“…Thus, there exists a need to study the potential to hot stamp 3G-AHSS which is motivated primarily by the industrial need to reduce press tonnage and springback. In addition, hot stamping of 3G-AHSS may offer other potential bene ts, such as improvement of the residual ductility following hot stamping, since the TRIP reaction is suppressed at elevated temperatures due to increased mechanical stability of the austenite phase at temperatures above 200°C, which may promote good global formability for secondary forming operations and for increased in-service (crash) ductility [25].…”

Section: Introductionmentioning

confidence: 99%

Development of a Quench and Partition Hot Stamping Process for a Third Generation 980 MPa Steel

Midawi,

Tolton,

George

et al. 2024

Preprint

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This paper explores the potential to hot stamp third generation steels, in this case a 980 MPa grade, while retaining or improving on the as-received microstructure, in particular the retained austenite (RA) fraction, and corresponding strength and ductility. Three classes of thermomechanical processes were investigated using a thermo-mechanical simulator system (Gleeble 3500). The first two processing routes considered a quenching and partitioning process starting from either a fully austenitic condition prior to quenching, designated the “Q&P” process, or an inter-critical partial austenitic condition, designated the “IC Q&P” process. In the two simulated Q&P processes, the samples were quenched to a predetermined temperature and then immediately transferred to a partitioning furnace. In the third processing route, designated the “Q&T” process, the samples were partially austenitized and then quenched to room temperature, followed by a tempering process to restore ductility. The conventional Q&P process resulted in excessive martensite formation, with high hardness and low ductility. The Q&T process produced a tempered martensite microstructure with hardness equivalent to the as-received sheet but with lower elongation and bendability. The IC Q&P heat treatment process increased the amount of retained austenite compared to the as-received sheet which translated into a higher yield strength, total elongation, and v-bend fracture angle. The IC Q&P ultimate tensile strength was approximately 8% lower than that of the as-received material. A sensitivity study was conducted to evaluate the influence of variations (±25 °C) in the intercritical austenitization temperature, quench temperature, and partitioning temperature on the resulting microstructure and microhardness. The final mechanical properties were observed to be relatively independent of these process variations, indicating that the IC Q&P hot stamping process appears to be robust.

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“…The high mechanical properties (strength and plasticity) of TRIP steel are obtained thanks to the phenomenon of additional plasticity during the transformation of metastable retained austenite into martensite during plastic deformation (Umwandlungsplastizit in Wassermann, 1937 [7], or Transformation-Induced Plasticity (TRIP) in Zackay, 1969 [8]) [9]. The TRIP effect occurs in three types of steel: austenitic stainless steels, nickel steels for cryogenic operation and low-alloy carbon steels with the addition of manganese, aluminium and/or silicon or phosphorus [10][11][12][13][14][15][16][17][18][19]. A TRIP-type structure in low alloy carbon steels can be obtained using a two-stage heat treatment process.…”

Section: Introductionmentioning

confidence: 99%

Determination of Two-Stage Heat Treatment Parameters in Industrial Conditions in Order to Obtain a TRIP Structure in Low-Alloy Carbon Steel Wires

et al. 2022

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The research presented in this article aimed to obtain a semi-finished product in the form of TRIP wires, which in further research will be used to produce fasteners in the form of KPS-6 screws used in the construction industry. At present, the process of manufacturing this type of fastener (from wire rod to the finished product) involves two technological lines: one for carrying out the drawing process and obtaining a semi-finished product in the form of a wire with appropriate properties, and the other for the production of fasteners. Semi-finished product wires with a ferritic-perlitic structure obtained after the drawing process are the starting product for the production of fasteners, the tensile strength of which is approximately 450 MPa. In order to be able to obtain fasteners characterized by an increased level of properties in 8.8 grade, after the screw manufacturing process, heat treatment should be carried out by hardening and tempering. The new technology proposed in the article includes: a drawing wire rod with a semi-finished product diameter, two-stage heat treatment on the line for pass-through heating and cooling, ensuring the obtaining of a TRIP-type structure in drawn wires, and calibration drawing. The product of this process was a wire whose tensile strength was in the range of 700–800 MPa with a TRIP structure. Thanks to obtaining a TRIP-type structure with the assumed amount of retained austenite, we obtained wires with higher strength properties and very high plasticity in relation to wires with the same chemical composition and ferritic and perlitic structure. The research carried out in the article also allowed us to obtain, in the semi-finished product wires, a favourable relationship between the strength properties and plasticity of the material, expressed by the value of the Re/Rm coefficient (yield strength/tensile strength) and the so-called yield ratio, which determines the material's susceptibility to cold deformation; the smaller these coefficients, the greater the yield strength. The subsequent stages of the research will include the development of forming fasteners in the form of KPS-6 screws used in the steel construction industry with TRIP structures, with increased properties of products in the 8.8 property class, without conducting heat treatment by hardening and tempering. It is assumed that the resulting product will have an additional usable feature: preserving a certain amount of retained austenite in the structure of the finished fasteners, which will be transformed into martensite during operation, and thus affect the longevity of the fasteners.

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Effect of Elevated Deformation Temperatures on Microstructural and Tensile Behavior of Si-Al Alloyed TRIP-Aided Steel

Cited by 5 publications

References 38 publications

Heat Treatment Design for a QP Steel: Effect of Partitioning Temperature

Heat Treatment Design for a QP Steel: Effect of Partitioning Temperature

Development of a Quench and Partition Hot Stamping Process for a Third Generation 980 MPa Steel

Determination of Two-Stage Heat Treatment Parameters in Industrial Conditions in Order to Obtain a TRIP Structure in Low-Alloy Carbon Steel Wires

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