Heat Treatment Effect on Microstructure Evolution in a 7% Cr Steel for Forging

High Silicon Austempered steels (AHSS) are materials of great interest due to their excellent combination of high strength, ductility, toughness, and limited costs. These steel grades are characterized by a microstructure consisting of ferrite and bainite, accompanied by a high quantity retained austenite (RA). The aim of this study is to analyze the effect of an innovative heat treatment, consisting of intercritical annealing at 780 °C and austempering at 400 °C for 30 min, on the microstructure and mechanical properties of a novel high silicon steel (0.43C-3.26Si-2.72Mn wt.%). The microstructure was characterized by optical and electron microscopy and XRD analysis. Hardness and tensile tests were performed. A multiphase ferritic-martensitic microstructure was obtained. A hardness of 426 HV and a tensile strength of 1650 MPa were measured, with an elongation of 4.5%. The results were compared with those ones obtained with annealing and Q&T treatments.

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“…Moreover martensite, formed after quenching, speeds up the kinetic of bainitic transformation and the process of austenite stabilization [22,23].…”

Section: Introductionmentioning

confidence: 99%

Effect of Intercritical Annealing and Austempering on the Microstructure and Mechanical Properties of a High Silicon Manganese Steel

Franceschi

Pezzato

Gennari

et al. 2020

Metals

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“…Material's uniformity improvement and increase at the treatment using increasing or complicating the tools set can be justified economically only for forging ingots made of high alloy steels or rare metals [27]. To equal the mechanical properties over the product cross-section, deformation schedules are combined directly [28] or stepped [29] heat treatment. However, investigations described in [30] deserve attention.…”

Section: Literature Reviewmentioning

confidence: 99%

Hydraulic Press Open Die Forging of 21CrMoV5-7 Steel CCM Roller with Flat Upper and Concave Semi-round Lower Cogging Dies

Kukhar

Vasylevskyi

Khliestova

et al. 2021

Lecture Notes in Mechanical Engineering

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The cogging schedules were investigated with reduction and rotation joint effect around the workpiece's longitudinal axis, making it possible to improve the shaft forgings quality indices in geometry and distribution of strength properties in cross-sections. The forging for the rollers of continuous casting machine (CCM) of 21XMoV5-7 steel was produced according to the improved process in the forging shop with the hydraulic press combined dies (the upper die is flat, the lower die is semi-round cut-out, U-shaped). The advantage of the developed shaft forging schedules is the significant plastic deformation achievement in the forging crosssection using only one combined dies set. Manufacture of the CCM roller forging according to the new process made it possible to improve by 8.9% in the average yield strength and by 11.9% in the average ultimate tensile strength. It was possible to reduce the forging the data spread for the yield strength from 33% to 17% and the data dispersion for the ultimate tensile strength from 26% to 11%. The minimal ultimate tensile strength was increased by 14.7%.

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“…The microstructural evolution of ferritic steels under different thermo-mechanical treatments has been discussed in [45,46]. In the literature, many studies have investigated the effect of different thermo-mechanical treatments (TMTs) on the irradiation resistance of EUROFER97 steel and, various strategies have been adopted to refine the microstructure (e.g., [47][48][49][50]).…”

Section: Introductionmentioning

confidence: 99%

Grain Refinement and Improved Mechanical Properties of EUROFER97 by Thermo-Mechanical Treatments

et al. 2021

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EUROFER97 steel plates for nuclear fusion applications are usually manufactured by hot rolling and subsequent heat treatments: (1) austenitization at 980 °C for 30 min, (2) rapid cooling and (3) tempering at 760 °C for 90 min. An extended experimental campaign was carried out with the scope of improving the strength of the steel without a loss of ductility. Forty groups of samples were prepared by combining cold rolling with five cold reduction ratios (20, 40, 50, 60 and 80%) and heat treatments at eight different temperatures in the range 400–750 °C (steps of 50 °C). This work reports preliminary results regarding the microstructure and mechanical properties of all the cold-rolled samples and the effects of heat treatments on the samples deformed with the greater CR ratio (80%). The strength of deformed samples decreased as heat treatment temperature increased and the change was more pronounced in the samples cold-rolled with greater CR ratios. After heat treatments at temperature up to 600 °C yield stress (YS) and ultimate tensile strength (UTS) of samples deformed with CR ratio of 80% were significantly larger than those of standard EUROFER97 but ductility was lower. On the contrary, the treatment at 650 °C produced a fully recrystallized structure with sub-micrometric grains which guarantees higher strength and comparable ductility. The work demonstrated that EUROFER97 steel can be strengthened without compromising its ductility; the most effective process parameters will be identified by completing the analyses on all the prepared samples.

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Heat Treatment Effect on Microstructure Evolution in a 7% Cr Steel for Forging

Cited by 27 publications

References 44 publications

Effect of Intercritical Annealing and Austempering on the Microstructure and Mechanical Properties of a High Silicon Manganese Steel

Effect of Intercritical Annealing and Austempering on the Microstructure and Mechanical Properties of a High Silicon Manganese Steel

Hydraulic Press Open Die Forging of 21CrMoV5-7 Steel CCM Roller with Flat Upper and Concave Semi-round Lower Cogging Dies

Grain Refinement and Improved Mechanical Properties of EUROFER97 by Thermo-Mechanical Treatments

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