Effect of Grain Refinement on Tensile Properties in Fe&amp;ndash;25Cr&amp;ndash;1N Alloy

Onomoto, Tatsuro; Terazawa, Yusuke; Tsuchiyama, Toshihiro; Takaki, Setsuo

doi:10.2355/isijinternational.49.1246

Cited by 23 publications

(16 citation statements)

References 15 publications

(21 reference statements)

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“…1.1 mass% nitrogen was added by using solution nitriding process at 1 473 K for 43 ks in nitrogen gas under the pressure of 0.1 MPa. 1) Since the grain size becomes significantly large after this heat treatment, grain refinement was performed using two-step phase transformation as follows.…”

Section: Methodsmentioning

confidence: 99%

“…The concept that dislocation glide controls the BDT suggests that the BDT temperature in austenitic steels should also be influenced by the change in the dislocation mobility. Onomoto et al 15) reported that adding Cu in Ni-free austenitic stainless steels decreases the yield stress. It suggests the decrease in BDT temperatures of Ni-free austenitic stainless steels as long as the BDT is controlled by dislocating glide.…”

Section: Introductionmentioning

confidence: 99%

“…Since nitrogen is a strong austenite former, it is possible to obtain metastable austenite at room temperature without nickel when a large amount of nitrogen is absorbed in steels. [1][2][3][4][5][6][7] Although Ni-free austenitic steels are expected to be used not only for biocompatible materials but also for structural materials, high-nitrogen austenitic steels show a brittle-to-ductile transition (BDT) [4][5][6] which needs to be overcome in order to promote their further utilizations as structural materials.…”

Section: Introductionmentioning

confidence: 99%

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Decrease in the Brittle-to-ductile Transition Temperature in Cu Added Nickel-free Austenitic Stainless Steels

et al. 2014

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Brittle-to-ductile transition (BDT) in Cu added Ni-free austenitic stainless steel was investigated. Temperature dependence of apparent fracture toughness was measured using four-point bending tests, indicating that the BDT temperature was decreased with the increase in the Cu content. The activation energy was obtained from the deformation rate dependence of BDT temperatures. It was found that the values of the activation energy was decreased with the increase in the Cu content, suggesting that the dislocation mobility in austenitic stainless steels was increased by Cu addition. The increase in the dislocation mobility induces the decrease in the BDT temperature. The values of the activation energy are deviated from the regression line drawn on the data which obtained from the materials with high Peierls potentials. Temperature dependence of 0.2% proof stress indicated that the effective stress was nearly independent from the Cu content while the values of activation volume were decreased with the increase in the Cu content. A model for dislocation glide was proposed to explain the both decrease in the activation energy and the activation volume with the increase in the Cu content.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Decrease in the Brittle-to-ductile Transition Temperature in Cu Added Nickel-free Austenitic Stainless Steels

et al. 2014

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“…(4) pile-up of planer dislocations against grain boundaries: 7) the rare opportunity of cross-slip induces pile-up dislocations against grain boundaries, leading to high stress intensity around the grain boundaries which causes fracture. It is still ambiguous, however, why high-nitrogen austenitic steels exhibit the BDT behaviour.…”

Section: Introductionmentioning

confidence: 99%

Brittle-to-ductile Transition in Nickel-free Austenitic Stainless Steels with High Nitrogen

et al. 2012

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The brittle-to-ductile transition (BDT) behaviour in nickel-free austenitic stainless steel with high nitrogen was investigated. Fall-weight impact tests revealed that Fe-25mass%Cr-1.1mass%N austenitic steel exhibits a sharp BDT behaviour in spite of an fcc alloy. The aspects of plastic deformation after the impact tests indicate that the BDT observed in this austenitic steel is induced by poor ductility at low temperatures as is the same as that in ferritic steels. In order to measure the activation energy for the BDT, the strain rate dependence of the BDT temperature was examined by using four-point bending tests. The weak dependence of the BDT temperature on the strain rate was observed. The Arrhenius plot of the BDT temperature against the strain rate elucidated that the activation energy for the BDT of Fe-25mass%Cr-1.1mass%N is much higher than that of low carbon ferritic steels. The origins of such distinct BDT behaviour and its large value of the activation energy in this high-nitrogen steel are discussed in terms of the reduction of dislocation mobility at low temperatures due to the interaction between glide dislocations and nitrogen solute atoms.

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“…Holding time for long duration produce excessive grain size. To overcome grain coarsening, some refinement methods have been developed [8]. The refinement methods promise the prospective application of HTGN treatment in industry.…”

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High Temperature Gas Nitriding Treatment of Aisi 430 Using Low and High Purity Nitrogen Gas

Suprihanto

2016

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IntroductionOnes of materials which widely use in industry is stainless steel due high resistance to corrosion and appropriate mechanical properties. Stainless steel is ferrous alloys which contains at least 11% chromium. Depending on the phase in the microstructure, stainless steel can be grouped as austenitic, ferritic or martensitic.AISI 430 is the most widely produced ferritic stainless steel. AISI 430 is cheapest and fairly good corrosion resistance in a variety of environments. However in certain uses such as high corrosive environments, the mechanical properties and corrosion resistance are less fulfilling. In order to improve its properties, this stainless steel can be treated by high temperature gas nitriding (HTGN) treatment.HTGN treatment is able to enhance the properties of stainless steel such as strength, hardness, wear resistance and corrosion resistance [1]. These treatments not only improve the properties, but also it can modify the initial phase [2,3]. The research of HTGN treatment for AISI 430 has been conducted by many investigators [4,5]. Depending on the variable process, the micro structure of ferritic stainless steel AISI 430 can be modified into martensitic which hard or austenitic stainless steel which soft and non-magnetic.The basic process of HTGN is by exposing the stainless steel in high purity nitrogen gas atmosphere at temperature 1050 o C ± 50 o C within certain time prior quenching [6]. During the process, nitrogen gas become dissociate into two nitrogen atom prior diffuses into stainless steel.The effects HTGN treatment on the properties of stainless steel depends on the amounts of nitrogen atom which diffuse into stainless steel. The resulting effects depend on the process variable such as chemical composition of stainless steel, temperature process, nitrogen gas pressure and duration of holding time [1,6,7].Generally, the increasing strength obtained after treatment is not higher than increasing of its hardness due to the grain coarsening. Holding time for long duration produce excessive grain size. To overcome grain coarsening, some refinement methods have been developed [8]. The refinement methods promise the prospective application of HTGN treatment in industry.Despite HTGN treatment use high purity nitrogen gas, there are several grade of purity on the market. The highest purity and the most expensive grade is scientific or research grade which has minimum purity 99.9999%. The other grades are ultra high purity (UHP) grade (99.999%), zero grade (99.998%), specialized zero grade (99.998%), oxygen free grade (99.998%) and industrial/welding grade (99.5%). The grade purity of nitrogen gas depends on the percentage of moisture, oxygen, hydrocarbon, and CO x .The most widely available grade is industrial or welding grade. The industrial/welding grade promises in cost production reduction for HTGN treatment. However, the effect of nitrogen gas purity on the effect of HTGN treatment ABSTRACTThe properties of stainless steels can be improved by high temperature gas nitriding (HT...

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Effect of Grain Refinement on Tensile Properties in Fe–25Cr–1N Alloy

Cited by 23 publications

References 15 publications

Decrease in the Brittle-to-ductile Transition Temperature in Cu Added Nickel-free Austenitic Stainless Steels

Decrease in the Brittle-to-ductile Transition Temperature in Cu Added Nickel-free Austenitic Stainless Steels

Brittle-to-ductile Transition in Nickel-free Austenitic Stainless Steels with High Nitrogen

High Temperature Gas Nitriding Treatment of Aisi 430 Using Low and High Purity Nitrogen Gas

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