Abnormal expansion during the ferro- to para-magnetic transition in pure iron

Park, Jihye; Jung, Minsu; Lee, Young Kook

doi:10.1016/j.jmmm.2014.10.092

Cited by 7 publications

(4 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(ii) a contraction stage (A 2 -A 3 ) due to the a/g transformation, during which the interface is moving back into the original ferrite phase. The abnormal expansion part (marked by the red dashed rectangle) during heating in both alloys is related to the magnetic transition, which has also appeared in pure iron near the Curie temperature and is thought to be caused by a change of electronephonon interaction under the radio frequency field [33]. Moreover, as arrowed in Fig.…”

Section: Microstructuresmentioning

confidence: 81%

“…As for the a/g transformation, the approximately linear dilation in the heating (B 1 -B 2 ) and in the cooling (B 3 -B 4 ) cycle can be considered as stagnant stage; for both alloys a distinctive contraction (B 2 -B 3 ) is observed after the isothermal holding at 790 C, during which the interface migrates back into the original ferrite. Again, the abnormal diameter change in both alloys during heating and cooling is deemed to be a variation of electronephonon interaction during magnetic transition [33], though the variation degree of heating is smaller than that of cooling due to the faster heating rate (5 C/s). Emphasis should be placed on the nonlinear expansion stage (B 4 -B 5 ), which is attributed to the g/a transformation.…”

Section: Interaction Between A/g Interface and Ipd Carbides During G/a Transformationmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of the interaction between moving α/γ interfaces and interphase precipitated carbides during cyclic phase transformations in a Nb-containing Fe-C-Mn alloy

et al. 2018

View full text Add to dashboard Cite

The interaction between moving a/g interfaces and interphase precipitated (IPd) carbides during the austenite (g) to ferrite (a) and the ferrite (a) to austenite (g) transformation has been systematically investigated through cyclic phase transformation experiments for a 0.1C-1.5Mn alloy containing 0.1 wt% Niobium (Nb) and its Nb-free counterpart. Shifts in the critical reaction temperatures during continuous heating and cooling are observed, which are attributed to the pinning force (PF) originating from the IPd carbides present. By applying the Gibbs energy balance (GEB) model to analyze experimental results, the PF was derived to be about 15 J/mol for the a/g transformation and about 5 J/mol for the g/a transformation, respectively, both of which are quite small compared to chemical driving force of phase transformations. Moreover, various modified Zener pinning equations have also been used to predict the PF, and it was found that these values are comparable with those obtained from experiments, which suggests that the classical Zener theory still has promising potential for carbide-interface interaction analysis.

show abstract

Section: Microstructuresmentioning

confidence: 81%

Section: Interaction Between A/g Interface and Ipd Carbides During G/a Transformationmentioning

confidence: 99%

Analysis of the interaction between moving α/γ interfaces and interphase precipitated carbides during cyclic phase transformations in a Nb-containing Fe-C-Mn alloy

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The thermodynamic calculations in Figure 8 predicted the possible precipitation and dissolution of other intermetallic compounds besides Ni 3 (Ti,Al) starting from 533 • C, which might possibly superimpose to the α' → γ reversion, thus further complicating the interpretation of DSC and dilatometric curves. Another possibly involved transformation is the ferromagnetic-to-paramagnetic transition at the Curie temperature TC, which, however, should appear as a contraction on dilatometric curves [56]. Therefore, the variety of possible microstructural changes occurring within the temperature range corresponding to peak II does not enable the complete identification of all the observed peaks.…”

Section: Resultsmentioning

confidence: 99%

Aging Behaviour of a 12.2Cr-10Ni-1Mo-1Ti-0.6Al Precipitation-Hardening Stainless Steel Manufactured via Laser Powder Bed Fusion

Morri,

Zanni,

Ceschini

et al. 2023

Metals

View full text Add to dashboard Cite

The combination of precipitation-hardening stainless steels (PH-SS) and laser powder bed fusion (LPBF) enables the manufacturing of tools for plastic injection moulding with optimised geometry and conformal cooling channels, with potential benefits in terms of productivity, part quality, and tool duration. Moreover, the suitability of LPBF-manufactured PH-SS in the as-built (AB) condition to be age-hardened through a direct aging (DA) treatment enables a great heat treatment simplification with respect to the traditional solution annealing and aging treatment (SA). However, plastic injection moulding tools experience severe thermal cycles during their service, which can lead to over-aging of PH-SS and thus shorten tool life. Therefore, proper thermal stability is required to ensure adequate tool life and reliability. The aim of the present work is to investigate the aging and over-aging behaviour of a commercially available PH-SS (AMPO M789) manufactured by LPBF in the AB condition and after a solution-annealing treatment in order to evaluate the effect of the heat treatment condition on the microstructure and the aging and over-aging response, aiming at assessing its feasibility for plastic injection moulding applications. The AB microstructure features melt pool borders, oriented martensite grains, and a cellular solidification sub-structure, and was retained during aging and over-aging. On the other hand, a homogeneous and isotropic martensite structure was present after solution annealing and quenching, with no melt pool borders, cellular structure, or oriented grains. The results indicate no significant difference between AB and solution-annealed and quenched specimens in terms of aging and over-aging behaviour and peak hardness (in the range 580–600 HV), despite the considerably different microstructures. Over-aging was attributed to both the coarsening of strengthening precipitates and martensite-to-austenite reversion (up to ~11 vol.%) upon prolonged exposure to high temperature. Based on the results, guidelines to aid the selection of the most suitable heat treatment procedure are proposed.

show abstract

“…This should be owing to the time needed for the incubation of austenite nuclei that would improve the Ac 1 temperatures for a higher heating rate. The deviations from linear expansion during heating before Ac 1 were caused by the switching of the heating rate and the magnetic transition [ 35 ]. Figure 5 b shows the volume fraction of austenite calculated from the dilatometric curves.…”

Section: Resultsmentioning

confidence: 99%

Prediction of the Non-Isothermal Austenitization Kinetics of Fe-C-Cr Low Alloy Steels with Lamellar Pearlite Microstructure

Zhang

et al. 2022

Materials

View full text Add to dashboard Cite

The austenitization of low alloy steels during rapid heating processes was involved in many kinds of advanced heat treatment technologies. Most of the previous research on the austenitization kinetics was focused on the spherical pearlite microstructures, which were different from the lamellar pearlite microstructures. In the present research, to predict the non-isothermal austenitization process of an Fe-C-Cr steel with lamellar pearlite, a novel 3-dimensional (3D) cellular automata model, which considered the influences of the coupling diffusion of Cr and C, and the interfacial diffusion between pearlite lamellae and the pearlite lamellar orientation, was established based on the thermodynamic equilibrium data obtained from the Thermo-Calc software and the simulation results of the DICTRA module. To clarify the influences of the heating rate on the austenitization kinetics and validate the simulation results, the austenitization processes of a Fe-1C-1.41Cr steel for different heating rates were studied with a series of dilatometric experiments. The good agreements between the cellular automata simulation results and the experimental results showed that the newly proposed cellular automata model is reasonable. The experimental results show an obvious change of the transition activity energies from the low to high heating rates. The transition from partitioning local equilibrium (PLE) to non-partitioning local equilibrium (NPLE) mechanisms was proved with DICTRA simulations. Basing on the simulation results, the influences of the pearlite lamellae orientation on the austenitization kinetics and the topological aspects of austenite grains were evaluated. In addition, the topological aspects of the rapidly austenitized grains were also compared to the normal grains.

show abstract

Abnormal expansion during the ferro- to para-magnetic transition in pure iron

Cited by 7 publications

References 15 publications

Analysis of the interaction between moving α/γ interfaces and interphase precipitated carbides during cyclic phase transformations in a Nb-containing Fe-C-Mn alloy

Analysis of the interaction between moving α/γ interfaces and interphase precipitated carbides during cyclic phase transformations in a Nb-containing Fe-C-Mn alloy

Aging Behaviour of a 12.2Cr-10Ni-1Mo-1Ti-0.6Al Precipitation-Hardening Stainless Steel Manufactured via Laser Powder Bed Fusion

Prediction of the Non-Isothermal Austenitization Kinetics of Fe-C-Cr Low Alloy Steels with Lamellar Pearlite Microstructure

Contact Info

Product

Resources

About