Implications of carbon, nitrogen and porosity on the γ→α′ martensite phase transformation and resulting hardness in PM-steel Astaloy 85Mo

Damon, James; Dietrich, Stefan; Schulze, Volker

doi:10.1016/j.jmrt.2020.05.035

Cited by 15 publications

(7 citation statements)

References 32 publications

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“…Looking at the development of retained austenite as a function of depth, the three density states of Fe-85Mo result in similar quantities of retained austenite, which is in accordance with the elemental analysis and hardness measurements. Previous investigations have shown that the amount of retained austenite is independent of the porosity and in a comparable quantity to other works on the alloy Fe-0.85Mo [18]. In comparison, slightly higher quantities of retained austenite in depths of 0.05 mm with amounts of 15 Vol.-% are reported for Fe-1.5Mo-2Cu (Figure 6.)…”

Section: Residual Stress and Retained Austenitesupporting

confidence: 78%

High-cycle fatigue and surface layer stability of case-hardened PM-steels with graded porosity

et al. 2021

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In order to increase the fatigue performance of mechanically loaded PM-components, case hardening procedures can be used to improve the surface layer states in terms of hardness and residual stress. In this work, the effects of carbonitriding treatment on two typical PMsteels with multiple densities are investigated in terms of their surface layer state (hardness, residual stress and retained austenite) before and after fatigue testing and their resulting pulsating fatigue performance. The results confirm fatigue strengths that can be formulated linearly as a function of porosity as well as a cyclic stability of the surface layer condition at loads below the fatigue strength. Further optimisation of the fatigue strength can be expected by tailoring the surface layer with respect to residual stresses. Comparisons to other studies are difficult due to many process parameters, different load cases and limited data, but indicate comparable fatigue strengths.

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Section: Residual Stress and Retained Austenitesupporting

confidence: 78%

High-cycle fatigue and surface layer stability of case-hardened PM-steels with graded porosity

et al. 2021

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“…[ 30 ] Due to the dissolution of the hard carbides, the matrix becomes more and more enriched with C , which causes the hardness of the martensite to increase more and more. [ 31 ] The macrohardness of the microstructure also increases as a result. However, the increase in hardness is counteracted by the soft retained austenite remaining in the quenched structure.…”

Section: Resultsmentioning

confidence: 99%

Short‐Term Heat Treatment of the High‐Alloy Cold‐Work Tool Steel X153CrMoV12: Calculation of Metastable Microstructural States

Schuppener

Müller

Benito

et al. 2022

steel research int.

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The influence of short‐time heat treatment on the widely used and commercially available ledeburitic cold‐work tool steel 1.2379 (X153CrMoV12; AISI D2) is examined herein. Starting from a soft annealed initial condition, the influence of different austenitizing temperatures and holding times on the metastable microstructural states after heat treatment/hardening is investigated. The experimental implementation of the heat treatment is used in a quenching dilatometer, and a microstructural simulation model is built using these results. As validation of the model, on the one hand, the martensite start temperature (Ms) is used, measured experimentally by dilatometry. Additionally, the carbide content and distribution, as determined by quantitative image analysis, are compared with the simulated data and used as an indicator of the model accuracy. Through the developed simulation model, arbitrary heat treatment‐induced metastable microstructural states can be calculated. As a possible application of this model, the live‐adaption of the industrial heat treatment process in dependence on the batch chemical composition is discussed.

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“…The hardness of the outer rim is around 300 HV for ECR samples which indicates the presence of tempered martensite phase [2,48]. Since the carbon concentration of the ECR sample is very low (≈0.22 wt%), therefore, in this case, the hardness is expected to be low because the hardness of martensite mainly depends on the carbon concentration [2,50]. It is noticeable that the hardness value in the case of transition zones is ≈220 HV for both the samples due to the presence of lower bainite whereas, at the core or in the ferrite-pearlite region it is below 200 HV in the case of the plain sample and slightly higher for the ECR sample.…”

Section: Hardness Profilementioning

confidence: 99%

A comparative study on the microstructure, hardness and corrosion resistance of epoxy coated and plain rebars

Yadav¹,

Dey²,

Ghosh³

2022

Mater. Res. Express

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Corrosion of steel rebars and susceptibility of reinforcement steel to chloride ion attacks are the two major problems for the construction industries and thereby a huge amount of money is spent to repair it. Epoxy coating on the steel rebars can be one cost-effective solution to alleviate the detrimental effects of corrosion in concrete structures. In the present research, plain and epoxy coated rebar (ECR) samples were chosen to study the correlation between microstructure, hardness and corrosion performance. The microstructures of the investigated thermomechanically treated (TMT) rebars primarily reveal tempered martensitic rings at the outer surface followed by a narrow bainitic transition zone in between along with a ferrite-pearlite microstructure at the inner core. The corrosion resistance of plain and epoxy-coated rebars in naturally aerated 3.5% NaCl and 1% HCl solutions were studied using gravimetric test, open circuit potential (OCP) test, and linear polarization monitoring techniques. It has been witnessed that the corrosion current (icorr) has been shifted towards lower values and polarization resistance (Rp) values are higher for ECR samples which is a clear indication of higher corrosion resistance of the ECRs than the plain rebars. Energy dispersive spectroscopy (EDS) analysis reveals the presence of iron hydroxides and iron oxides. However, X-Ray diffraction (XRD) analysis indicates the existence of various types of oxides, hydroxides, and oxy-hydroxides like iron chloride hydroxide [Fe2(OH)3Cl], goethite (α-FeO(OH)), lepidocrocite (γ-FeO(OH)), magnetite (Fe3O4) and bernalite [Fe(OH)3(H2O)0.25] in the epoxy coated rebar samples whereas, plain rebars indicate the presence of goethite (α-FeO(OH)), maghemite (γ-Fe2O3), magnetite (Fe3O4), hydrogoethite (Fe2O3.H2O), lepidocrocite (γ-FeO(OH)) and iron oxide (Fe21.34O32). All the experimental results confirm that ECR samples are more corrosion resistant under both acidic and saline environments.

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Implications of carbon, nitrogen and porosity on the γ→α′ martensite phase transformation and resulting hardness in PM-steel Astaloy 85Mo

Cited by 15 publications

References 32 publications

High-cycle fatigue and surface layer stability of case-hardened PM-steels with graded porosity

High-cycle fatigue and surface layer stability of case-hardened PM-steels with graded porosity

Short‐Term Heat Treatment of the High‐Alloy Cold‐Work Tool Steel X153CrMoV12: Calculation of Metastable Microstructural States

A comparative study on the microstructure, hardness and corrosion resistance of epoxy coated and plain rebars

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