Effect of Mn and Cr on the selective oxidation, surface segregation and hot-dip Zn coatability

Samanta, Santigopal; Halder, Arup Kumar; Deo, Yashwardhan; Guha, Sounak; Dutta, Moumita

doi:10.1016/j.surfcoat.2019.124908

Cited by 18 publications

(9 citation statements)

References 55 publications

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“…6b. Samanta et al 44 reported similar Mn and Cr-rich external oxides for a Cr containing AHSSs (∼0.50 wt%) annealed at 800 °C in a N 2 -5 vol% H 2 process atmosphere with a -40 °C T dp . Further analysis of Fig.…”

Section: Resultsmentioning

confidence: 81%

“…Nevertheless, this result is consistent with the observations reported by various researchers with Mn and Cr containing AHSSs. 43,44,51 For example, Swaminathan 51 reported external MnCr 2 O 4 formation owing to chemical interactions between Mn and Cr at process atmosphere T dp ⩾ -40 °C for a Fe-2Mn-0.8Cr (wt%) alloy. In the present research, thin film-type external MnCr 2 O 4 was observed alongside nodule-type MnO for the M (-10 °C T dp ) and M (+5 °C T dp ) samples (Figs.…”

Section: Discussionmentioning

confidence: 99%

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Selective Oxidation of a Medium-Mn Third Generation Advanced High Strength Steel during Austenitizing and Intercritical Annealing

Bhadhon

McDermid

2022

J. Electrochem. Soc.

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The effect of the simulated continuous galvanizing line N2-5 vol% H2 process atmosphere oxygen partial pressure (pO2) on the external and internal selective oxidation of a prototype medium-Mn third generation (3G) advanced high strength steel was determined during a two-stage heat treatment cycle (i.e., austenitizing and intercritical annealing) which had previously yielded 3G properties. Thick external oxides (~ 200 nm) were observed after the austenitizing heat treatment, regardless of the process atmosphere pO2 employed. An intermediate flash pickling step was successful in reducing the external oxide thickness significantly (to ~ 30 nm) along with revealing some extruded metallic Fe nodules on the surface. The austenitizing heat treatment also resulted in a solute-depleted surface layer with a minimum thickness of 2 µm. This solute-depleted layer inhibited the formation of external oxides during intercritical annealing, resulting in a surface similar to that observed after flash pickling comprising a near-pure Fe surface with isolated, nodular external oxides. These surfaces are promising in terms of successful reactive wetting of this prototype medium-Mn steel during subsequent continuous hot-dip galvanizing.

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Section: Resultsmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Selective Oxidation of a Medium-Mn Third Generation Advanced High Strength Steel during Austenitizing and Intercritical Annealing

Bhadhon

McDermid

2022

J. Electrochem. Soc.

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“…[ 51 ] This analysis confirmed that the external oxides consisted mainly of MnCr 2 O 4 , consistent with the findings of several selective oxidation studies of Cr‐containing AHSSs. [ 60,61 ] Moreover, the presence of extruded Fe nodules and boldly exposed substrate was confirmed for the surface, as shown in Figure 4b. The internal oxides mainly comprised Si and Al, with some Mn and Cr enrichment.…”

Section: Resultsmentioning

confidence: 70%

Continuous Hot‐Dip Galvanizing of Medium‐Manganese Third‐Generation Advanced High‐Strength Steels

Bhadhon

Pallisco

McDermid

2023

steel research int.

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The effects of process atmosphere oxygen partial pressure (pO2) on the preimmersion surface structures, interfacial reactive wetting products, and reactive wetting mechanisms of two prototype (0.15–0.20)C–(5.6–5.9)Mn–(0.4–1.9)Al–(1.1–1.5)Si–(0–0.6)Cr (wt%) third‐generation advanced high‐strength steels during continuous hot‐dip galvanizing are determined. In this study, the two‐stage thermal processing routes employed comprise an austenitization anneal followed by flash pickling and an intercritical anneal. All annealing treatments are conducted in a N2–5 vol% H2 process atmosphere with a controlled dew point. The substrates are austenitized at dew points of –30 or –10 °C, intercritically annealed at a dew point of –30, –10, or +5 °C, and then galvanized using a conventional 0.2 wt% Al (dissolved) bath. The preimmersion surfaces comprise a near‐pure Fe layer with dispersed nanoscaled oxide nodules. The primary reactive wetting mechanism is the direct wetting of the surface Fe, while oxide wetting, oxide cracking and liftoff, and oxide bridging by the liquid metal bath are secondary reactive wetting mechanisms. Zn ingress into the substrate via pores in the oxide network from selective dissolution during flash pickling is also noted. A well‐developed Fe2Al5–xZnx interfacial layer is observed for all metallic coating conditions. The resultant coatings show outstanding adherence after ASTM three‐point bend testing.

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“…However, these alloying elements are easy to be oxidized in the hot-dip galvanizing annealing process. The presence of film-like or granulated SiO 2 and MnO surface oxides lead to deterioration of the reactive wettability of liquid zinc and hindrance of the formation of Fe-Al-Zn inhibition layer, thus worsening the quality of zinc coatings [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Effect of Hot-Dip Galvanizing Process on Selective Oxidation and Galvanizability of Medium Manganese Steel for Automotive Application

Chen

Zheng

et al. 2020

Coatings

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A medium manganese steel with 7.5 wt.% Mn for automobile application was galvanized in a continuous Hot Dip Galvanizing (HDG) simulator under different galvanizing conditions. It was shown that the effects of dew point, annealing temperature and annealing atmosphere on the surface oxidation of steel could be comprehensively evaluated by the consideration of oxygen partial pressure P(O2). Although Mn2SiO4 was a thermodynamic stable phase when P(O2) varied from 10−28 to 10−21 atm, it was difficult to form Mn–Si–O composite oxide because there was no enrichment of silicon on the steel surface. So, this oxide was generally formed in the Fe substrate and had little effect on the galvanizability. With the increase in P(O2) above 10−25 atm, MnO particles in the form of the thermodynamic stable phase became coarser and tended to aggregate, which hindered the formation of a continuous inhibition layer, resulting in the defects of bare spots on the galvanized surface of the steel. When the oxygen partial pressure greater than 10−22 atm, film-like MnO layer was formed on the surface of steel sample, which obviously deteriorated the galvanizability. The galvanizability of the steel can be improved by the regulation of oxygen partial pressure; based on this, the reasonable zinc plating process parameters can be developed.

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Effect of Mn and Cr on the selective oxidation, surface segregation and hot-dip Zn coatability

Cited by 18 publications

References 55 publications

Selective Oxidation of a Medium-Mn Third Generation Advanced High Strength Steel during Austenitizing and Intercritical Annealing

Selective Oxidation of a Medium-Mn Third Generation Advanced High Strength Steel during Austenitizing and Intercritical Annealing

Continuous Hot‐Dip Galvanizing of Medium‐Manganese Third‐Generation Advanced High‐Strength Steels

Effect of Hot-Dip Galvanizing Process on Selective Oxidation and Galvanizability of Medium Manganese Steel for Automotive Application

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