Effect of molybdenum, aluminium and boron on the phase transformation in 4 ​wt.–% manganese steels

Gramlich, Alexander; Linde, C. van der; Ackermann, Marc; Bleck, Wolfgang

doi:10.1016/j.rinma.2020.100147

Cited by 18 publications

(9 citation statements)

References 24 publications

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“…Additionally, the dilatometer experiments revealed that for the investigated medium manganese steel, the bainitic transformation was suppressed completely, even for slow cooling with t 8/5 >1 h, due to the alloying concept with 5 wt.% Mn and a relatively high 0.3 wt.% C. The decrease in hardness with slower cooling rates can be explained by self-tempering of martensite below M s . As suggested by Gramlich et al [23], the reduction in soluted C in the matrix due to the diffusion of C to lattice defects might be a reason for lower martensite hardness. The same effect was observed by Sackl et al [24] by atom-probe tomography analysis on 42CrMo4.…”

Section: Phase Transformations and Initial Statementioning

confidence: 84%

Influence of Quenching and Partitioning Parameters on Phase Transformations and Mechanical Properties of Medium Manganese Steel for Press-Hardening Application

Blankart

Wesselmecking

Krupp

2021

Metals

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It has been proven that through targeted quenching and partitioning (Q & P), medium manganese steels can exhibit excellent mechanical properties combining very high strength and ductility. In order to apply the potential of these steels in industrial press hardening and to avoid high scrap rates, it is of utmost importance to determine a robust process window for Q & P. Hence, an intensive study of dilatometry experiments was carried out to identify the influence of quenching temperature (TQ) and partitioning time (tp) on phase transformations, phase stabilities, and the mechanical properties of a lean medium manganese steel. For this purpose, additional scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and energy dispersive X-ray spectroscopy (EDX) examinations as well as tensile testing were performed. Based on the dilatometry data, an adjustment of the Koistinen–Marburger (K-M) equation for medium manganese steel was developed. The results show that a retained austenite content of 12–21% in combination with a low-phase fraction of untempered secondary martensite (max. 20%) leads to excellent mechanical properties with a tensile strength higher than 1500 MPa and a total elongation of 18%, whereas an exceeding secondary martensite phase fraction results in brittle failure. The optimum retained austenite content was adjusted for TQ between 130 °C and 150 °C by means of an adapted partitioning.

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Section: Phase Transformations and Initial Statementioning

confidence: 84%

Influence of Quenching and Partitioning Parameters on Phase Transformations and Mechanical Properties of Medium Manganese Steel for Press-Hardening Application

Blankart

Wesselmecking

Krupp

2021

Metals

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“…The sample deformed at 500 °C exhibited a comparatively larger average grain size and a higher number fraction of grains with core–shell structure following partial recrystallization resulting in a slightly lower fraction of stabilized austenite and the formation of more FM. The average M s temperatures and stacking fault energies (SFE) of RA in various samples were estimated using the following equations [ 57 , 58 ]: M s = 517 − 423C − 30.4Mn − 7.5Si + 30Al SFE = 1.2 + 1.4 (Ni + 0.5Mn + 0.3Cu + 30C) + 0.6 (Cr + 2Si + 1.44B) …”

Section: Resultsmentioning

confidence: 99%

Heterogeneous Multiphase Microstructure Formation through Partial Recrystallization of a Warm-Deformed Medium Mn Steel during High-Temperature Partitioning

et al. 2022

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A novel processing route is proposed to create a heterogeneous, multiphase structure in a medium Mn steel by incorporating partial quenching above the ambient, warm deformation, and partial recrystallization at high partitioning temperatures. The processing schedule was implemented in a Gleeble thermomechanical simulator and microstructures were examined by electron microscopy and X-ray diffraction. The hardness of the structures was measured as the preliminary mechanical property. Quenching of the reaustenitized sample to 120 °C provided a microstructure consisting of 73% martensite and balance (27%) untransformed austenite. Subsequent warm deformation at 500 °C enabled partially recrystallized ferrite and retained austenite during subsequent partitioning at 650 °C. The final microstructure consisted of a heterogeneous mixture of several phases and morphologies including lath-tempered martensite, partially recrystallized ferrite, lath and equiaxed austenite, and carbides. The volume fraction of retained austenite was 29% with a grain size of 200–300 nm and an estimated average stacking fault energy of 45 mJ/m2. The study indicates that desired novel microstructures can be imparted in these steels through suitable process design, whereby various hardening mechanisms, such as transformation-induced plasticity, bimodal grain size, phase boundary, strain partitioning, and precipitation hardening can be activated, resulting presumably in enhanced mechanical properties.

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“…As mentioned before, the austenite stability can be approximated by

M_{normals}

. In some empirical calculation formulae, [ 12,27–29 ] aluminum addition increases the

M_{normals}

, thus it stabilizes the martensitic phase. This is what can be seen in the greater amounts of thermally induced martensite (Table 1) of aluminum‐containing MAS compared to aluminum‐free MAS.…”

Section: Discussionmentioning

confidence: 99%

Influence of Aluminum on the Wear Properties of High‐Carbon Metastable Austenitic Steels

Ingber

Duchek

Kunert

2022

steel research int.

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The two‐body abrasive wear properties of metastable austenitic steels (MAS) against SiC abrasive paper are investigated at different wear loads. To ensure a metastable austenitic microstructure, the alloying compositions are chosen such that the martensite start temperature of the MAS is approximately at room temperature, while the proportions of carbon, manganese, and aluminum change. The abrasion test results are compared to martensitic (40MnB5) and austenitic steel (Hadfield steel). An up to four times lower weight loss is found for the MAS compared to the Hadfield steel and up to 6.7 times lower weight loss compared to the martensitic steel. It is found that the wear resistance of the MAS increases significantly with wear load. Wear resistance of over 1300 Nm mm−3 is achieved at the highest wear load of 32 N. The wear properties of the MAS are associated with an increase in the surface hardness resulting from a mechanically induced austenite to martensite phase transformation. It is shown that the addition of aluminum to the MAS reduces the wear resistance. This is explained by an increase in stacking fault energy and the associated restriction of the mechanically induced transformation to martensite.

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Effect of molybdenum, aluminium and boron on the phase transformation in 4 wt.–% manganese steels

Cited by 18 publications

References 24 publications

Influence of Quenching and Partitioning Parameters on Phase Transformations and Mechanical Properties of Medium Manganese Steel for Press-Hardening Application

Influence of Quenching and Partitioning Parameters on Phase Transformations and Mechanical Properties of Medium Manganese Steel for Press-Hardening Application

Heterogeneous Multiphase Microstructure Formation through Partial Recrystallization of a Warm-Deformed Medium Mn Steel during High-Temperature Partitioning

Influence of Aluminum on the Wear Properties of High‐Carbon Metastable Austenitic Steels

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Effect of molybdenum, aluminium and boron on the phase transformation in 4 ​wt.–% manganese steels

Cited by 18 publications

References 24 publications

Influence of Quenching and Partitioning Parameters on Phase Transformations and Mechanical Properties of Medium Manganese Steel for Press-Hardening Application

Influence of Quenching and Partitioning Parameters on Phase Transformations and Mechanical Properties of Medium Manganese Steel for Press-Hardening Application

Heterogeneous Multiphase Microstructure Formation through Partial Recrystallization of a Warm-Deformed Medium Mn Steel during High-Temperature Partitioning

Influence of Aluminum on the Wear Properties of High‐Carbon Metastable Austenitic Steels

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Effect of molybdenum, aluminium and boron on the phase transformation in 4 wt.–% manganese steels