On the α′ to γ transformation in maraging (grade 350), PH 13-8 Mo and 17-4 PH steels

Kapoor, R.; Batra, I.S.

doi:10.1016/j.msea.2003.12.023

Cited by 55 publications

(51 citation statements)

References 24 publications

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“…Furthermore, they suggested that for smaller heating rates (see Table 2), the redistribution of solute reaches a sufficient level in order to allow precipitation on dislocations by pipe diffusion (due to lower activation energies). Guo et al 22 and Kapoor and Batra 21 have been observed that for higher heating rates, solute diffusion would be occurring by lattice diffusion (due to higher activation energies). In addition, from Table 2 it may be observed that the estimated activation energies for lattice diffusion are very close to those of the activation energies for lattice diffusion of the Ti (272 kJ/mol) and Mo (238 kJ/mol) in ferrite (similar to martensite) 16,22 .…”

Section: Resultsmentioning

confidence: 99%

“…According to Habiby et al 19 and Kapoor et al 21 , the solute in the matrix during heating leads to precipitation in the maraging steels causing a lattice contraction and changes of specimen macroscopic dimensions. Figures 2, 3 and 4 show the temperatures where the maximum rate of phase transformation for precipitation and martensite reversion occurred.…”

Section: Resultsmentioning

confidence: 99%

“…It must be pointed out, in Figure 2, 3 and 4, that for higher heating rates the time available for precipitation decreases leading to a smaller specimen contraction. This is due to the smaller quantity of precipitates formed during heating for higher heating rates 21 . For samples of bar A (maraging 300) a smaller contraction during precipitation could be observed when compared to samples of bar B and C (maraging 350).…”

Section: Resultsmentioning

confidence: 99%

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A dilatometric study of the phase transformations in 300 and 350 maraging steels during continuous heating rates

et al. 2013

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The influences of the chemical composition and heating rate have been studied in 300 and 350 maraging steels using dilatometry. For these tests, heating was carried out with heating rates of 1, 10 and 28 °C/s. The results have shown that the precipitation mechanism for both materials in the studied range is by lattice diffusion. Furthermore, Co and Ti contents influence strongly the precipitation. The lattice diffusion mechanism in the martensite reversion is influenced by Ni and Co contents and heating rate. For small heating rates ( ~1 °C/s) this mechanism prevails in the 300 maraging steel while for the 350 maraging steel has a minor importance. The mechanism of martensite reversion for 350 maraging steel in the studied range is mainly by shear mechanism. For higher heating rates (~28 ºC/s) the shear mechanism prevails in both maraging steels.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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A dilatometric study of the phase transformations in 300 and 350 maraging steels during continuous heating rates

et al. 2013

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“…First, the characteristic transformation temperatures are shifted to higher temperatures with increasing heating rate, which is a well-known effect due to the thermally activated character of the transformation. [15,[39][40][41][42] Phase transformations can take place by either a diffusional or a shear mechanism. [43,44] Diffusional transformation of martensite to austenite is in general heating rate dependent, whereas a shear transformation is independent of the heating rate.…”

Section: A Austenite Formation In Two Stagesmentioning

confidence: 99%

“…[43,44] Diffusional transformation of martensite to austenite is in general heating rate dependent, whereas a shear transformation is independent of the heating rate. [15,40,45] Thus, the martensite-to-austenite transformation in the present study can be assumed to be diffusional. For Table IV).…”

Section: A Austenite Formation In Two Stagesmentioning

confidence: 99%

Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

Bojack

Zhao

Morris

et al. 2016

Metall Mater Trans A

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The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two stages. This is probably due to inhomogeneous distribution of the austenite-stabilizing elements Ni and Mn, resulting from their slow diffusion from martensite into austenite and carbide and nitride dissolution during the second, higher temperature, stage. A better homogenization of the material causes an increase in the transformation temperatures for the martensite-to-austenite transformation and a lower retained austenite fraction with less variability after tempering. Furthermore, the martensite-to-austenite transformation was found to be incomplete at the target temperature of 1223 K (950°C), which is influenced by the previous austenitization treatment and the heating rate. The activation energy for martensite-to-austenite transformation was determined by a modified Kissinger equation to be approximately 400 and 500 kJ/mol for the first and the second stages of transformation, respectively. Both values are much higher than the activation energy found during isothermal treatment in a previous study and are believed to be effective activation energies comprising the activation energies of both mechanisms involved, i.e., nucleation and growth.

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Designing Ultrahigh Strength Steels with Good Ductility by Combining Transformation Induced Plasticity and Martensite Aging

et al. 2009

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Steels with a high ultimate tensile strength (UTS) above 1 GPa and good ductility [total elongation (TE) of 15-20% in a tensile test] are of paramount relevance for lightweight engineering design strategies and corresponding CO 2 savings, Figure 1. [1,2] In this work, we report about a novel design approach for precipitation hardened ductile high strength martensitic and austenitic-martensitic steels (up to 1.5 GPa strength). The alloys are characterized by a low carbon content (0.01 wt% C), 9-15 wt% Mn to obtain different levels of austenite stability, and minor additions of Ni, Ti, and Mo (1-2 wt%). The latter are required for creating precipitates during aging heat treatment.Hardening in these materials is realized by combining the TRIP effect with a maraging treatment [transformationinduced plasticity (TRIP); maraging: martensite aging through thermally stimulated precipitation of particles]. The TRIP mechanism is based on the deformation-stimulated athermal transformation of metastable austenite (face centered cubic Fe-Mn phase) into martensite (metastable body centered cubic or orthorhombic Fe-Mn phase) and the resulting matrix and martensite plasticity required to accommodate the transformation misfit. [3][4][5][6][7][8][9][10][11] The maraging treatment is based on hardening the heavily strained martensite through the formation of small intermetallic precipitates (of the order of several nanometers). These particles act as highly efficient obstacles against dislocation motion through the Orowan and Fine-Kelly mechanisms enhancing the strength of the material. [12][13][14][15][16][17] While both types of alloys, i.e., TRIP steels [3][4][5][6][7][8][9][10][11] and maraging steels [12][13][14][15][16][17] have been well investigated, the combination of the two mechanisms in the form of a set of simple Fe-Mn alloys as suggested in this work, namely, the precipitation hardening of transformation-induced martensite by intermetallic nanoparticles, opens a novel and lean alloy path to the development of ultrahigh strength steels that has not been much explored in the past. [18,19] We refer to these alloys as maraging TRIP steels.Related steel design trends that are based on small-scaled second phase precipitates are also pursued by using oxide, [20][21][22][23] nitride, [24,25] or Cu nanosized particles. [26] Other pathways to the design of ultrahigh strength steels have been realized in ultra fine grained materials obtained by advanced thermomechanical processing [27][28][29][30][31][32][33][34] or by accumulative roll bonding. [35] The joint maraging TRIP approach justifies a more detailed study since it opens up a new approach to increase the UTS of conventional steels at relatively lean alloying costs, i.e., without large quantities of expensive alloying elements, owing to the small volume fraction of precipitates required in maraging steels. [12][13][14][15][16][17] The negative side of such strategies lies often in the fact that an increase in tensile strength is typically accompanied by a corresponding dro...

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On the α′ to γ transformation in maraging (grade 350), PH 13-8 Mo and 17-4 PH steels

Cited by 55 publications

References 24 publications

A dilatometric study of the phase transformations in 300 and 350 maraging steels during continuous heating rates

A dilatometric study of the phase transformations in 300 and 350 maraging steels during continuous heating rates

Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

Designing Ultrahigh Strength Steels with Good Ductility by Combining Transformation Induced Plasticity and Martensite Aging

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