Microstructural refinement of duplex stainless steels

Soylu, B.; Honeycombe, R. W. K.

doi:10.1179/026708391790182980

Cited by 13 publications

(10 citation statements)

References 3 publications

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“…[1][2][3][4][5][6][7][8][9][10][11] Because precipitation of Cu particles in steels improves the high-temperature and fatigue strength, [12][13][14][15] many studies on the precipitation of Cu in stainless steels have been conducted. [16][17][18][19][20][21] Bajguirani et al [17][18][19] reported that precipitation of Cu particles in a 15-5 PH stainless steel occurs first by formation of coherent bcc solute clusters. These clusters then transform into twinned 9R particles, and then into 3R and fcc Cu particles.…”

Section: Introductionmentioning

confidence: 99%

Effect of Nb Addition on the Growth and Coarsening of Cu-particles in Ferritic Stainless Steel

Kobayashi

Takeda

et al. 2014

ISIJ Int.

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The growth and coarsening of Cu-particles in 18%Cr-1.5%Cu ferritic stainless steels as a function of Nb content was investigated quantitatively. The samples were solution-treated at 1 250°C and then isothermally aged at 700°C for up to 86 400 s. Fine, spherical Cu-particles nucleated and grew during aging. The radius of the Cu particles increased in proportion to the one-third power of the aging time in all the stainless steels. The radius of the Cu particles in the Nb-added stainless steels was always smaller than that in the Nb-free stainless steel. The normalized standard deviation of the size distribution of the Cu particles increased and reached saturation at a certain value during aging. The increase in the standard deviation during aging was delayed by the addition of Nb. The volume fraction of Cu particles increased and reached saturation at a certain value during aging. The addition of niobium delayed the saturation of the volume fraction of the Cu particles. The slow growth of Cu particles in Nb-added stainless steels is thought to be owing to the slow diffusion of Nb atoms from the Cu particles.

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Section: Introductionmentioning

confidence: 99%

Effect of Nb Addition on the Growth and Coarsening of Cu-particles in Ferritic Stainless Steel

Kobayashi

Takeda

et al. 2014

ISIJ Int.

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“…19,20) Precipitation of Cu particles in stainless steels can also be found in the literature. [21][22][23][24][25][26] Soylu and Honeycombe studied formation of Cu precipitates in a duplex stainless steel. 21) They reported that first stage of Cu precipitation in ferrite was the formation of bcc coherent Cu-rich zones and bcc Cu-rich zones transformed to fcc Cu particles.…”

Section: Introductionmentioning

confidence: 99%

“…[21][22][23][24][25][26] Soylu and Honeycombe studied formation of Cu precipitates in a duplex stainless steel. 21) They reported that first stage of Cu precipitation in ferrite was the formation of bcc coherent Cu-rich zones and bcc Cu-rich zones transformed to fcc Cu particles. Formation of Cu particles in a PH 15-5 stainless steel was studied in detail by Habibi Bajguirani et al [22][23][24] They showed that Cu-rich precipitation in a PH 15-5 began with the formation of coherent bcc clusters which subsequently transformed to twinned 9R, 3R and fcc-Cu particles.…”

Section: Introductionmentioning

confidence: 99%

Effect of Nb Addition on Cu Precipitation in Ferritic Stainless Steel

et al. 2011

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Formations of Cu-rich precipitate in 18%Cr-1.5%Cu stainless steels without and with 0.5%Nb have been examined mainly using transmission electron microscopy. The specimens solution-treated at 1250°C were isothermally transformed at various temperatures between 500 and 850°C. Fine spherical Cu-rich solute zones were nucleated in the steels in the beginning of aging. These Cu-rich zones exhibited bcc structure and then transformed into 9R structure with twins during aging. The spherical 9R-Cu particles changed into rod-shaped fcc-Cu particles after prolonged aging. Laves phase of Fe2Nb type started to form in the Nb-added steel almost after finishing nucleation and growth of Cu particles. Addition of Nb in the steel delayed the nucleation of the Cu-rich zones due to slow diffusion of Nb atoms in ferrite.

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“…[4][5][6][7][8][9] On the other hand, the improvement of steel properties containing fine Cu precipitates has been reported. [10][11][12][13][14][15] For instance, by controlling of Cu precipitation, it became possible to produce high tensile strength and high r-value steel products. 10) Fine-grained duplex stainless steels were also developed by using Cu precipitates as the nucleation sites of the ferrite during austenite/ferrite phase transformation.…”

Section: Introductionmentioning

confidence: 99%

“…10) Fine-grained duplex stainless steels were also developed by using Cu precipitates as the nucleation sites of the ferrite during austenite/ferrite phase transformation. 15) That is, Cu in steel causes the hot shortness but fine Cu precipitates improve the steel performance. To solve the problem of hot shortness and to utilize Cu precipitates, the behavior of Cu precipitation in Fe-Cu alloys should be properly understood.…”

Section: Introductionmentioning

confidence: 99%

Effects of MnS on the Heterogeneous Nucleation of Cu Precipitates in Fe-10 and -5mass% Cu Alloys

2003

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Copper in steel has been thought harmful because of the hot shortness at grain boundaries, but Cu precipitates finely distributed inside of each grain increase the strength. If the problem of hot shortness is solved, scrap recycling will become much easier and even Cu can be used as an important alloying element. It is therefore most important to investigate the behavior of Cu precipitation in Fe-Cu alloys at high temperatures. In this study, in-situ observation of the Cu precipitation on cooling in Fe-10mass%Cu and Fe-5mass%Cu alloys was made using a confocal scanning laser microscope. The precipitates were analyzed by SEM-EDX after in-situ observation experiments.As a result the effect of MnS inclusion on the heterogeneous nucleation of Cu precipitate was made clear. In Fe-10 mass%Cu alloy containing MnS inclusions, the starting temperature of Cu precipitation became higher and its distribution became more uniform than the same alloy without MnS inclusions. In case of Fe-5mass%Cu alloy containing MnS inclusions, some of Cu precipitates appeared in g phase before the g/a phase transformation. In case of the same alloy without MnS inclusions, many fine Cu precipitates appeared in a phase after the g/a phase transformation. The complex precipitate of MnS and Cu was also found indicating that Cu precipitated at MnS inclusion. The reason for these facts was explained by the heterogeneous nucleation theory. The undercooling for the Cu precipitation was estimated to be smaller in the alloy with MnS inclusions than in another case. Based on these results, if the nucleation sites such as MnS inclusions are finely distributed beforehand, the heterogeneous nucleation of Cu precipitates will be accelerated and its distribution will be made very fine.KEY WORDS: in-situ observation; Cu precipitation; MnS inclusions; laser microscope; heterogeneous nucleation.nificantly affects the precipitation behavior. Fe-5mass%Cu alloy and Fe-10mass%Cu alloy were selected in the present study. Figure 1 shows the phase diagram of Fe-Cu-C alloy system. In Fe-10mass%Cu alloys the liquid Cu precipitates appear at 1 526 K in g phase and the g/a phase transformation occurs at 1 130 K in equilibrium state. In Fe-5mass%Cu alloys the solid e-Cu precipitates appear at 1 238 K in g phase and the g/a phase transformation occurs at 1 130 K in equilibrium state. Experimental Methods SamplesAbout 100 g of pure electrolytic iron was melted and alloyed in a tungsten arc furnace under an argon gas atmosphere. The ingot was machined into a disc (4.3 mm in diameter, 2 mm in height) and the surface was mirror polished. The chemical composition of samples is shown in Table 1. Copper content of both samples A and B was the same as about 10 mass% but sample A was without MnS and sample B was with MnS. Copper content of both samples C and D was again the same as about 5 mass% but sample C was without MnS and sample D was with MnS. In order to make clear the effect of MnS on the Cu precipitation, the content of Mn and S in samples B and D was determined to be 0.6...

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Microstructural refinement of duplex stainless steels

Cited by 13 publications

References 3 publications

Effect of Nb Addition on the Growth and Coarsening of Cu-particles in Ferritic Stainless Steel

Effect of Nb Addition on the Growth and Coarsening of Cu-particles in Ferritic Stainless Steel

Effect of Nb Addition on Cu Precipitation in Ferritic Stainless Steel

Effects of MnS on the Heterogeneous Nucleation of Cu Precipitates in Fe-10 and -5mass% Cu Alloys

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