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Schino, Andrea Di; Mecozzi, M.G.; Barteri, M.; Kenny, J. M.

doi:10.1023/a:1004774130483

Cited by 78 publications

(25 citation statements)

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“…Although developed to predict the amount of delta ferrite content, these indexes have also been used to establish correlations among composition, properties and microstructures in stainless steel castings and cast samples. [16][17][18] Regardless of its application, a practical method and its equivalent indexes have been chosen from the methods discussed previously usually without any type of justification.…”

Section: Introductionmentioning

confidence: 99%

Predicting Delta Ferrite Content in Stainless Steel Castings

2012

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The distribution of delta ferrite fraction was measured with the magnetic method in specimens of different stainless steel compositions cast by the investment casting (lost wax) process. Ferrite fraction measurements published in the literature for stainless steel cast samples were added to the present work data, enabling an extensive analysis about practical methods to calculate delta ferrite fractions in stainless steel castings. Nineteen different versions of practical methods were formed using Schaeffler, DeLong, and Siewert diagrams and the nickel and chromium equivalent indexes suggested by several authors. These methods were evaluated by a detailed statistical analysis, showing that the Siewert diagram, including its equivalent indexes and iso-ferrite lines, gives the lowest relative errors between calculated and measured delta ferrite fractions. Although originally created for stainless steel welds, this diagram gives relative errors lower than those for the current ASTM standard method (800/A 800M-01), developed to predict ferrite fractions in stainless steel castings. Practical methods originated from a combination of different chromium/nickel equivalent indexes and the iso-ferrite lines from Schaeffler diagram give the lowest relative errors when compared with combinations using other iso-ferrite line diagrams. For the samples cast in the present work, an increase in cooling rate from 0.78 to 2.7 K/s caused a decrease in the delta ferrite fraction, but a statistical hypothesis test revealed that this effect is significant in only 50% of the samples that have ferrite in their microstructures.

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Section: Introductionmentioning

confidence: 99%

Predicting Delta Ferrite Content in Stainless Steel Castings

2012

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“…It is well known that the mechanical properties of austenitic stainless steels are sensitive to chemical composition (which can induce hardening by substitutional as well as interstitial solid solutions) and grain size [2]. Recently, performance enhancements including an increase in the yield strength have been achieved by nitrogen addition [3].…”

Section: Introductionmentioning

confidence: 99%

Friction and Wear Behavior of Austenitic Stainless Steel: Influence of Atmospheric Humidity, Load Range, and Grain Size

et al. 2004

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Research conducted on steels is motivated by a technological need to further improve their properties. Among the different steel types, austenitic stainless steels possess good corrosion resistance and formability. However, they also have a relatively low yield strength. One way of increasing the yield strength is by grain refining. This work presents a study on the effect of relative humidity and applied load range on the friction and wear of AISI 304 austenitic stainless steel characterized by two different grain sizes: 2.5 and 40 lm. Using a precision microtribometer, with applied loads in the lN regime, it was found that capillarity plays a dominant role. At the same loads, in high humidity environments, both the fine and coarse grain steels exhibit high friction relative to measurements performed under dry conditions. At loads greater than 2 mN a reversal in microfrictional behavior occurs in that microfriction was greater under dry conditions than under moist conditions. At loads of 2 N, using a standard ball-on-disk tribometer, severe wear was evident at low humidities while relatively lower wear was observed at high humidities indicating a lubricating effect of water.

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“…In summary, as a result of a specific solidification path along which an alloy undergoes, significant partitioning of alloying elements take place. 6,8,9,11,[13][14][15]17,18) Numerous papers have been published on morphology and characterization of sulfides in steel. Among sulfides, manganese sulfide (MnS) is commonly observed and utilized in steel, especially in free machining grades, and extensive studies have been devoted to understanding the formation of MnS.…”

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confidence: 99%

The Effect of Alloy Solidification Path on Sulfide Formation in Fe–Cr–Ni Alloys

et al. 2009

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Solidification and sulfide precipitation in Fe-Cr-Ni alloys were investigated. Five samples containing 0.3 wt% S and 1.5 wt% Mn were investigated and each sample chemistry was adjusted to solidify as primary austenite, primary ferrite or eutectic by tailoring the Cr and Ni contents. 355© 2009 ISIJ or g, depending on the balance between Cr and Ni contents. In the 70wt%Fe-Cr-Ni system, if Ni content is less than 10-12 wt%, the alloy will encounter the d-liquidus first and begin to form d phase when it is cooled down from the liquid state, while if Ni content exceeds 10-12 wt% it will solidify as g phase first after passing the g-liquidus during cooling. 8,10,16) At this stage of solidification, the partition of Fe, Cr and Ni between the liquid and the primary solid phase is dependent on the slope of liquidus surface; i.e., the primary solid phase is rich in Fe and the remained liquid is rich in Cr and Ni. 6,8,15) In the region where Ni content lies between 10-12 wt%, the remaining liquid undergoes a eutectic reaction at the latter stage of solidification where the three phases coexist. When the liquid composition reaches a eutectic valley, partitions of solute elements in d and g phases will occur through eutectic reaction; i.e., d phase is rich in Cr and g phase rich in Ni. In summary, as a result of a specific solidification path along which an alloy undergoes, significant partitioning of alloying elements take place. 6,8,9,11,[13][14][15]17,18) Numerous papers have been published on morphology and characterization of sulfides in steel. Among sulfides, manganese sulfide (MnS) is commonly observed and utilized in steel, especially in free machining grades, and extensive studies have been devoted to understanding the formation of MnS.19-25) When S content is small (e.g., less than 1 wt%), MnS will form either in a monotectic or a eutectic manner during solidification, depending on the amounts of other alloying elements such as C, Si and Al. 20,22) Although these elements are not constituents of sulfides, they can switch the formation process of MnS from monotectic to eutectic reaction by lowering melting temperature of the metal matrix or supplying nucleation sites for MnS, which results in the change in morphology of sulfides. 20,22) Besides this change in sulfide morphology potentially caused by these elements, solidification structures, d, g, or the mixture of d and g, can influence the sulfide morphology as well as distribution and composition because partitions of S and sulfide forming elements vary from phase to phase which has a specific solubility limit of sulfide. Since sulfide morphology, distribution and composition have a critical effect on hot crack susceptibility, it is necessary to have a basic understanding of how sulfides precipitate in different solidification modes.Several researchers carried out in-situ observation of sulfide formation using a confocal scanning laser microscope (CSLM). 26,27) In Si-killed and Al-killed steels, MnS was seen to form rapidly as a film on the surface of the interd...

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Cited by 78 publications

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Predicting Delta Ferrite Content in Stainless Steel Castings

Predicting Delta Ferrite Content in Stainless Steel Castings

Friction and Wear Behavior of Austenitic Stainless Steel: Influence of Atmospheric Humidity, Load Range, and Grain Size

The Effect of Alloy Solidification Path on Sulfide Formation in Fe–Cr–Ni Alloys

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