New Manufacturing Process of Nickel-Free Austenitic Stainless Steel with Nitrogen Absorption Treatment

2004 ◽  
Vol 449-452 ◽  
pp. 1085-1088
Author(s):  
Daisuke Kuroda ◽  
Takao Hanawa ◽  
Takaaki Hibaru ◽  
Syuji Kuroda ◽  
Masaki Kobayashi ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Stainless Steels ◽  
Manufacturing Process ◽  
Austenitic Stainless Steels ◽  
Nitrogen Absorption ◽  
Proof Stress ◽  
Nitrogen Gas ◽  
Ferritic Stainless Steels ◽  
316L Steel ◽  
Reduction Of Area

Ingots of ferritic stainless steels, Fe-24Cr and Fe-24Cr-2Mo in mass%, were worked to various dimensions for test specimens. Nitrogen was absorbed by the specimens in a furnace filled with nitrogen gas with a pressure of 101.3 kPa at 1473 K to develop a simple and convenient manufacturing process of nickel-free austenitic stainless steels. Ferritic Fe-24Cr and Fe-24Cr-2Mo were austenitized with nitrogen absorption to a 2-mm depth from the surface. The hardness, tensile strength, 0.2% proof stress, and elongation to fracture increased, and the reduction of area decreased in the alloys by austenitization due to nitrogen absorption. The tensile strength and 0.2% proof stress of these alloys with nitrogen absorption for 129.6 ks were much larger than those of 316L steel, while the elongation to fracture was much smaller than that of 316L steel. Therefore, small devices and parts with a maximum thickness or diameter of 4 mm were manufactured with this process in this study

Effects of External and Internal Hydrogen on Tensile Properties of Austenitic Stainless Steels Containing Additive Elements

2015 ◽  
Author(s):  
Hisatake Itoga ◽  
Hisao Matsunaga ◽  
Junichiro Yamabe ◽  
Saburo Matsuoka
Keyword(s):  
Stainless Steels ◽  
Room Temperature ◽  
Austenitic Stainless Steels ◽  
Hydrogen Gas ◽  
Nitrogen Gas ◽  
Material Compatibility ◽  
Internal Hydrogen ◽  
The Stability ◽  
Reduction Of Area ◽  
Nickel Equivalent

Effect of hydrogen on the slow strain rate tensile (SSRT) properties of five types of austenitic stainless steels, which contain small amounts of additive elements (e.g., nitrogen, niobium, vanadium and titanium), was studied. Some specimens were charged by exposing them to 100 MPa hydrogen gas at 543 K for 200 hours. The SSRT tests were carried out under various combinations of specimens and test atmospheres as follows: (i) non-charged specimens tested in air at room temperature (RT), (ii) non-charged specimens tested in 0.1 MPa nitrogen gas at 193 K, (iii) hydrogen-charged specimens tested in air at RT, (iv) hydrogen-charged specimens tested in 0.1 MPa nitrogen gas at 193 K, and (v) non-charged specimens tested in 115 MPa hydrogen gas at RT. In the tests without hydrogen (i.e., cases (i) and (ii)), the reduction of area (RA) was nearly constant in all the materials, regardless of test temperature. In contrast, in the tests of internal hydrogen (cases (iii) and (iv)), RA was much smaller at 193 K than at RT in all the materials. It was revealed that the susceptibility of the materials to hydrogen embrittlement (HE) can successfully be estimated in terms of the nickel equivalent, which represents the stability of austenite phase. The result suggested that the nickel equivalent can be used for evaluating the material compatibility of austenitic stainless steels for hydrogen service.

Proposal of Fatigue Life Equations for Carbon and Low-Alloy Steels and Austenitic Stainless Steels as a Function of Tensile Strength

2013 ◽  
Author(s):  
Hiroshi Kanasaki ◽  
Makoto Higuchi ◽  
Seiji Asada ◽  
Munehiro Yasuda ◽  
Takehiko Sera
Keyword(s):  
Tensile Strength ◽  
Fatigue Life ◽  
Stainless Steels ◽  
Room Temperature ◽  
Austenitic Stainless Steels ◽  
Low Alloy Steels ◽  
Strength Based ◽  
Fatigue Data ◽  
Current Design ◽  
Alloy Steels

Fatigue life equations for carbon & low-alloy steels and also austenitic stainless steels are proposed as a function of their tensile strength based on large number of fatigue data tested in air at RT to high temperature. The proposed equations give a very good estimation of fatigue life for the steels of varying tensile strength. These results indicate that the current design fatigue curves may be overly conservative at the tensile strength level of 550 MPa for carbon & low-alloy steels. As for austenitic stainless steels, the proposed fatigue life equation is applicable at room temperature to 430 °C and gives more accurate prediction compared to the previously proposed equation which is not function of temperature and tensile strength.

Comparison of Microstructure and Mechanical Behavior of the Ferritic Stainless Steels ASTM 430 Stabilized with Niobium and ASTM 439 Stabilized with Niobium and Titanium

2016 ◽  
Vol 879 ◽  
pp. 1651-1655 ◽  
Author(s):  
Leandro Paulo de Almeida Reis Tanure ◽  
Cláudio Moreira de Alcântara ◽  
Tarcísio Reis de Oliveira ◽  
Dagoberto Brandão Santos ◽  
Berenice Mendonça Gonzalez
Keyword(s):  
Stainless Steels ◽  
Lower Cost ◽  
Volume Fraction ◽  
Austenitic Stainless Steels ◽  
Total Elongation ◽  
Drawing Ratio ◽  
Limit Drawing Ratio ◽  
Soaking Time ◽  
Ferritic Stainless Steels ◽  
Cold Rolled

The use of Ferritic Stainless Steels has become indispensable due its lower cost and the possibility to replace austenitic stainless steels in many applications. In this study, cold rolled sheets of two stabilized ferritic stainless steels with 85% thickness reduction were annealed by applying a heating rate of 24 oC/s and a soaking time of 24 s. The niobium stabilized ferritic stainless steel type ASTM 430 (430Nb) was annealed at 880 oC while the niobium and titanium bi-stabilized steel ASTM 439 was annealed at 925 oC. The annealed samples were tensile tested and due to the smaller grain size, steel 430Nb, showed a higher yield stress and a higher total elongation. Concerning drawability the steel ASTM 439 presented a better performance with higher average R-value, lower planar anisotropy coefficient and a greater value for Limit Drawing Ratio (LDR). These results are explained in terms of the differences in size and volume fraction of precipitates between the two steels.

Influence of Oxygen Concentration on the Initiation of Dissolution Corrosion on 316L Austenitic Stainless Steel at 450°C

2017 ◽  
Author(s):  
Oksana Klok ◽  
Konstantina Lambrinou ◽  
Serguei Gavrilov ◽  
Iris De Graeve
Keyword(s):  
Electron Microscopy ◽  
Oxygen Concentration ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
X Ray ◽  
First Results ◽  
316L Steel ◽  
316L Austenitic Stainless Steel ◽  
Dissolution Corrosion ◽  
Scanning Electron

This work presents first results of the study on the influence of the LBE oxygen concentration on the initiation of dissolution corrosion in 316L austenitic stainless steels. 316L steel specimens were exposed at 450 °C to static liquid LBE with controlled and constant oxygen concentration of 10−5, 10−6 and 10−7 mass% for 1000 hours. Corroded specimens were analysed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Limited oxidation corrosion and no dissolution corrosion was observed in the specimens exposed to LBE containing 10−5 and 10−6 mass% oxygen, while dissolution corrosion with a maximum depth of 59 μm was found in the specimen exposed to LBE containing 10−7 mass% oxygen.

Evaluation of Cross-Weld Properties of Austenitic Stainless Steels Before and After PWHT

2008 ◽  
Author(s):  
M. M. Ibrahim ◽  
H. G. Mohamed ◽  
Y. E. Tawfik ◽  
Ibrahim Taha
Keyword(s):  
Tensile Strength ◽  
Stainless Steels ◽  
Plate Thickness ◽  
Postweld Heat Treatment ◽  
Austenitic Stainless Steels ◽  
Tensile Tests ◽  
Steel Plates ◽  
Aisi 304L ◽  
Before And After ◽  
Weld Properties

Different types of austenitic stainless steels, which are commonly used for piping systems, tanks, and vessels, required postweld heat treatment (PWHT), at temperatures between 540 and 590 °C, regardless of the plate thickness. This paper reports on the weld procedures and cross-weld performance evalution of weldments in 6 mm AISI 304L, 316L, and 347 steel plates before and after PWHT. This welds were produced by SMAW and GTAW techniques using a single vee preparation and multiple weld beads, and welded by various types of consumables. After PWHT, tensile tests indicated a reduction in the ultimate tensile strength of all samples and a decrease in the yield strength for some cases only. The hardness results were consistent with the tensile test results because they both revealed significant softening in the HAZ and WM as a result of PWHT. In spite of the fact that PWHT exerts a beneficial effect on reducing residual stresses, it is concluded that the ductility of the weld region was satisfactory without PWHT, and PWHT decreased the cross-weld tensile strength.

Formation of the Surface Layer with Improved Tribological Properties on Austenitic Stainless Steel by Alloying with REE Using HIPPB

2014 ◽  
Vol 790-791 ◽  
pp. 479-484
Author(s):  
Bożena Sartowska ◽  
Marek Barlak ◽  
Lech Waliś ◽  
Jan Senatorski ◽  
Wojciech Starosta
Keyword(s):  
Surface Layer ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Industrial Applications ◽  
Pulsed Plasma ◽  
Near Surface ◽  
Heating And Cooling ◽  
316L Steel ◽  
Material Heating ◽  
Melted Material

Austenitic stainless steels with their very good corrosion resistance are used in industrial applications nuclear and petrochemical industries, pulp and paper chemical, food and chemical processing, biomedical industries and others. But poor tribological and mechanical properties of austenitic stainless steels limit their applications in engineering fields. AISI 316L steel was subjected to transient treatment using high intensity pulsed plasma beams HIPPB. The plasma pulses contained both ions/atoms of electrodes material: Ce, La or (Ce+La) and those of working gas. The pulse energy densities (3.0 J/cm2) were sufficient to melt the near surface layer of steel and introduce REE to the melted material. Heating and cooling processes were of non-equilibrium type.

scholarly journals Effect of Hydrogen on Tensile Strength and Ductility of Multi-Pass 304L / 308L Austenitic Stainless Steel Welds

2015 ◽  
Author(s):  
Dorian K. Balch ◽  
Chris San Marchi
Keyword(s):  
Tensile Strength ◽  
Stainless Steels ◽  
Tensile Elongation ◽  
Austenitic Stainless Steels ◽  
Tensile Specimen ◽  
Rolled Plate ◽  
Gas Tungsten Arc ◽  
Steel Welds ◽  
Weld Root ◽  
Strength And Ductility

Austenitic stainless steels such as 304L are frequently used for hydrogen service applications due to their excellent resistance to hydrogen embrittlement. However, welds in austenitic stainless steels often contain microstructures that are more susceptible to the presence of hydrogen. This study examines the tensile strength and ductility of a multi-pass gas tungsten arc weld made on 304L cross-rolled plate using 308L weld filler wire. Sub-sized tensile specimens were used to ensure the entire gage section of each tensile specimen consisted of weld metal. Specimens were extracted in both axial and transverse orientations, and at three different depths within the weld (root, center, and top). Yield strength decreased and ductility increased moving from the root to the top of the weld. A subset of specimens was precharged with hydrogen at 138 MPa (20,000 psi) and 300°C prior to testing, resulting in a uniform hydrogen concentration of 7700 appm. The presence of hydrogen resulted in a slight increase in yield and tensile strength and a roughly 50% decrease in tensile elongation and reduction in area, compared to the hydrogen-free properties.

Nanoscale Nickel-Free Austenitic Stainless Steel

2008 ◽  
Vol 140 ◽  
pp. 179-184 ◽  
Author(s):  
Maciej Tulinski ◽  
Karolina Jurczyk ◽  
Mieczyslaw Jurczyk
Keyword(s):  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Xrd Analysis ◽  
Human Osteoblast ◽  
Corrosion Properties ◽  
Nanoscale Structures ◽  
316L Steel ◽  
Normal Human ◽  
Mechanical And Corrosion Properties ◽  
Normal Human Osteoblast

In this work Ni-free austenitic stainless steels with nanostructure were synthesized by mechanical alloying (MA), heat treatment and nitrogenation of elemental Fe, Cr, Mn and Mo microcrystalline powders. The phase transformation from ferritic to austenitic was confirmed by XRD analysis. The mechanical and corrosion properties of the produced biomaterials were investigated. Additionally, the biocompatibility of nickel-free austenitic stainless steels with nanostructure and microcrystalline 316L steel, were analyzed studying the behaviour of Normal Human Osteoblast (NHOst) cells from Cambrex (CC-2538). An enhancement of the properties due to the nanoscale structures in the bulk consolidated materials was observed.

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