Evolution of Microstructure during Isothermal Treatments of a Duplex-Austenitic 0.66C11.4Mn.9.9Al Low-Density Forging Steel and Effect on the Mechanical Properties

Kaltzakorta, Idurre; Gutiérrez, Teresa; Elvira, Roberto; Jimbert, Pello; Guraya, Teresa

doi:10.3390/met11020214

Cited by 5 publications

(9 citation statements)

References 25 publications

(36 reference statements)

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“…The formation of kappa carbides in these steels instead of cementite is also observed [ 5 , 7 ]. With a suitable choice of morphology, distribution, proportion, and size, they can benefit the mechanical properties [ 8 ]. The aluminium content influences their precipitation.…”

Section: Introductionmentioning

confidence: 99%

“…Low density steels are divided into three different categories according to the carbon, aluminium, and manganese content: austenitic steels (0.5 < wt% C < 2, 8 < wt% Al < 12, 15 < wt% Mn < 30), duplex steels (0.1 < wt% C < 0.7, 3 < wt% Al < 10, 5 < wt% Mn < 30), and ferritic steels (wt% C < 0.03, 5 < wt% Al < 8, wt% Mn < 8) [ 8 , 14 ]. An advantage of using low-density steels (LDS) is the possibility of influencing the yield properties by (Fe, Mn) 3 AlC-type precipitates—kappa carbides and B2-type phases rich in Ni and Cu, respectively.…”

Section: Introductionmentioning

confidence: 99%

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A New Alloying Concept for Low-Density Steels

et al. 2022

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This paper introduces a new alloying concept for low-density steels. Based on model calculations, samples—or “heats”—with 0.7 wt% C, 1.45 wt% Si, 2 wt% Cr, 0.5 wt% Ni, and an aluminium content varying from 5 to 7 wt% are prepared. The alloys are designed to obtain steel with reduced density and increased corrosion resistance suitable for products subjected to high dynamic stress during operation. Their density is in the range from 7.2 g cm−3 to 6.96 g cm−3. Basic thermophysical measurements are carried out on all the heats to determine the critical points of each phase transformation in the solid state, supported by metallographic analysis on SEM and LM or the EDS analysis of each phase. It is observed that even at very high austenitisation temperatures of 1100 °C, it is not possible to change the two-phase structure of ferrite and austenite. A substantial part of the austenite is transformed into martensite during cooling at 50 °C s−1. The carbide kappa phase is segregated at lower cooling rates (around 2.5 °C s−1).

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A New Alloying Concept for Low-Density Steels

et al. 2022

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“…[ 13 ] The air hardening in this work did not only avoid cracks in sample but also minimized the possibility of κ‐carbide formation. This is not the case of austenite‐based duplex‐forged steel studied by Kaltzakorta et al, [ 10 ] which still reveals coarse κ‐carbide at the grain boundaries.…”

Section: Discussionmentioning

confidence: 83%

“…However, only very few research groups have studied this for forged products. [ 10,11 ] This paper focusses on the ferrite‐based duplex group of the medium‐manganese steel with a slightly different chemical composition from those published in the literature, [ 1–3,7,12 ] lying at the boundary of the group. Its higher manganese content (>6 wt%) is to avoid the formation of coarse κ‐carbide at forging temperatures and to stabilize the retained austenite during air‐cooling.…”

Section: Introductionmentioning

confidence: 99%

Study of Intercritical Annealing in Air‐Cooled Fe‐Mn‐Al‐C Lightweight Forging Steel for Tailoring the Mechanical Properties

Dickert

Suwanpinij

Bleck

2022

steel research int.

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Herein, the opportunity of lightweight medium‐manganese steel Fe‐7Mn‐6Al‐0.3C for forged components produced without quenching and tempering treatments is explored. The selected composition reveals neither cracks nor intergranular coarse κ‐carbide and has a lower density than pure iron by 9%. Despite the massive dimension of the forged bar and decreased thermal conductivity, outstanding mechanical properties can be achieved by air‐cooling followed by intercritical annealing. An intermediate tensile strength of 685 MPa with total elongation of 29% can be achieved by annealing at 800 °C for 1,000 s, whereas an ultimate tensile strength above 1,000 MPa with an elongation of 13% can be reached by forming tempered martensite with fine κ‐carbide at 400 °C.

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“…As steels are alloys mainly formed by one of the most abundant elements in the Earth's crust, and the most used engineering alloys; the development of new lightweight steels have become a hot topic in materials science. Hence, novel lightweight steels with improved specific strength and/or ductility have been developed, by alloying light elements such as Al or Si [6][7][8][9][10][11][12]. On the other hand, few investigations have been carried out to develop novel lightweight cast irons.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Evolution as a Function of Increasing Aluminum Content in Novel Lightweight Cast Irons

Obregon

Sánchez

Eguizabal

et al. 2021

Metals

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In the context of the development of new lightweight materials, Al-alloyed cast irons have a great potential for reducing the weight of the different part of the vehicles in the transport industry. The correlation of the amount of Al and its effect in the microstructure of cast irons is not completely well established as it is affected by many factors such as chemical composition, cooling rate, etc. In this work, four novel lightweight cast irons were developed with different amounts of Al (from 0 wt. % to 15 wt. %). The alloys were manufactured by an easily scalable and affordable gravity casting process in an induction furnace, and casted in a resin-bonded sand mold. The microstructural evolution as a function of increasing Al content by different microstructural characterization techniques was studied. The hardness of the cast irons was measured by the Vickers indentation test and correlated with the previously characterized microstructures. In general, the microstructural evolution shows that the perlite content decrease with the increment of wt. % of Al. The opposite occurs with the ferrite content. In the case of graphite, a slight increment occurs with 2 wt. % of Al, but a great decrease occurs until 15 wt. % of Al. The addition of Al promotes the stabilization of ferrite in the studied alloys. The hardness obtained varied from 235 HV and 363 HV in function of the Al content. The addition of Al increases the hardness of the studied cast irons, but not gradually. The alloy with the highest hardness is the alloy containing 7 wt. % Al, which is correlated with the formation of kappa-carbides and finer perlite.

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Evolution of Microstructure during Isothermal Treatments of a Duplex-Austenitic 0.66C11.4Mn.9.9Al Low-Density Forging Steel and Effect on the Mechanical Properties

Cited by 5 publications

References 25 publications

A New Alloying Concept for Low-Density Steels

A New Alloying Concept for Low-Density Steels

Study of Intercritical Annealing in Air‐Cooled Fe‐Mn‐Al‐C Lightweight Forging Steel for Tailoring the Mechanical Properties

Microstructural Evolution as a Function of Increasing Aluminum Content in Novel Lightweight Cast Irons

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