Precipitation Strengthening Of Rapidly Solidified Austenitic Stainless Steels

1983 ◽  
Vol 28 ◽  
Author(s):  
J. Megusar ◽  
A. Chaudhry ◽  
D. Imeson ◽  
N. J. Grant

ABSTRACTPrecipitation kinetics was studied in a rapidly solidified 316 stainless steel containing 0.22% C and 1% Ti. A high density of fine TiC particles was obtained by annealing at 923 to 973 K. An increase in recrystallization temperature and room temperature yield strength was observed as compared with the rapidly solidified 316 stainless steel with a nominal carbon and titanium content. An extension of solid solubility by rapid solidification thus offers a potential for developing precipitation strengthened austenitic stainless steels to improve structural and mechanical stability and likely the irradiation resistance.

Alloy Digest ◽  
1990 ◽  
Vol 39 (8) ◽  

Abstract ARMCO NITRONIC 40 Stainless Steel is one of the most versatile austenitic stainless steels with a room-temperature yield strength about twice that of AISI Types 304, 321 and 347. In addition, NITRONIC 40 has remarkably good elevated temperature properties and oxidation resistance. It retains high toughness down to -423 F. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness and creep. It also includes information on low temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-327. Producer or source: Armco Advanced Materials Corporation. Originally published as Nitronic 40, May 1976, revised August 1990.


Alloy Digest ◽  
2020 ◽  
Vol 69 (10) ◽  

Abstract ATI 310S is a 25Cr-20Ni austenitic stainless steel that is typically used for elevated temperature applications. Owing to its higher chromium and nickel contents the alloy provides comparable corrosion resistance, superior resistance to oxidation, and the retention of a larger fraction of room temperature strength than the common austenitic stainless steels such as Type 304. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-1328. Producer or source: ATI.


Author(s):  
Joseph A. Ronevich ◽  
Chris San Marchi ◽  
Dorian K. Balch

Austenitic stainless steels are typically used in hydrogen environments due to their resistance to hydrogen embrittlement; however, the behavior of welds is not as well understood and can vary from wrought base materials due to chemical composition differences and the presence of ferrite in the fusion zone of the weld. Applications of welded austenitic stainless steels exposed to hydrogen are not limited to room temperature but also include sub-ambient environments, which can have an additional effect on the degradation. In this study, fracture thresholds were measured of three different austenitic stainless steel welds in the hydrogen-precharged condition. Forged 304L, 316L, and 21Cr-6Ni-9Mn stainless steels were gas tungsten arc welded with 308L filler metal and machined into 3-pt bend bars for fracture testing. Crack growth resistance (J-R) curves were measured of the three welds in the hydrogen-precharged condition at ambient (293 K) and sub-ambient (223 K) temperatures to determine the effects of temperature on fracture threshold. Fracture thresholds were determined using elastic-plastic fracture mechanics through development of J-R curves to determine the stress intensity factor following standard practice for determination of fracture toughness. Fracture threshold tests for the welds revealed significant susceptibility to subcritical cracking when tested in the hydrogen-precharged condition. The 21-6-9/308L and 304L/308L welds exhibited some variability in fracture thresholds that did not appear to trend with temperature, while the 316L/308L weld exhibited a reduction of over 50% in fracture threshold at the lower temperature compared to room temperature. In addition to fracture testing, mini-tensile specimens were extracted from the weld region and tested at 293 K and 223 K in the hydrogen-precharged condition. Hydrogen-precharging slightly increased the yield strength relative to the as-welded condition for all three welds at both temperatures. For all three welds, hydrogen reduced the total elongation by 3–11% at 293 K, whereas reductions in total elongation from 50–64% were observed at 223 K (relative to room temperature without hydrogen). The role of slip planarity on hydrogen-induced degradation of ductility and fracture resistance is discussed as a function of temperature, nickel content, and hydrogen. The fracture surfaces were examined to elucidate the observed differences and similarities in mechanical properties.


Author(s):  
Jussi Solin ◽  
Sven Reese ◽  
Wolfgang Mayinger

The new stainless steel air curve endorsed in NRC RG 1.207 for new US designs only was recently adopted into ASME III without restrictions on applicability. We assume that the new (2009b) ASME curve may be applicable to some grades of stainless steel, but not to all. This paper reports contradictory data for stabilized austenitic stainless steels extending up to 10 million cycles in room temperature at air environment. Niobium and titanium stabilized stainless steel specimens were sampled from 100% relevant material batches fabricated for NPP primary piping. Additional research and more recent data for titanium stabilized steel suggest that our PVP 2009-78138 conclusions are not limited to one material grade. Therefore, the revised ASME design curve cannot be considered universally applicable.


Alloy Digest ◽  
1999 ◽  
Vol 48 (8) ◽  

Abstract ALZ 316 is an austenitic stainless steel with good formability, corrosion resistance, toughness, and mechanical properties. It is the basic grade of the stainless steels, containing 2 to 3% molybdenum. After the 304 series, the molybdenum-containing stainless steels are the most widely used austenitic stainless steels. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-756. Producer or source: ALZ nv.


Alloy Digest ◽  
1998 ◽  
Vol 47 (2) ◽  

Abstract ALLOY 0Cr25Ni6Mo3CuN is one of four grades of duplex stainless steel that were developed and have found wide applications in China since 1980. In oil refinement and the petrochemical processing industries, they have substituted for austenitic stainless steels in many types of equipment, valves, and pump parts. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on low and high temperature performance, and corrosion resistance as well as forming and joining. Filing Code: SS-706. Producer or source: Central Iron & Steel Research Institute.


Alloy Digest ◽  
2021 ◽  
Vol 70 (9) ◽  

Abstract CarTech 347 is a niobium+tantalum stabilized austenitic stainless steel. Like Type 321 austenitic stainless steel, it has superior intergranular corrosion resistance as compared to typical 18-8 austenitic stainless steels. Since niobium and tantalum have stronger affinity for carbon than chromium, carbides of those elements tend to precipitate randomly within the grains instead of forming continuous patterns at the grain boundaries. CarTech 347 should be considered for applications requiring intermittent heating between 425 and 900 °C (800 and 1650 °F). This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-1339. Producer or source: Carpenter Technology Corporation.


2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
K. A. Habib ◽  
M. S. Damra ◽  
J. J. Saura ◽  
I. Cervera ◽  
J. Bellés

The failure of the protective oxide scales of AISI 304 and AISI 316 stainless steels has been studied and compared at 1,000°C in synthetic air. First, the isothermal thermogravimetric curves of both stainless steels were plotted to determine the time needed to reach the breakdown point. The different resistance of each stainless steel was interpreted on the basis of the nature of the crystalline phases formed, the morphology, and the surface structure as well as the cross-section structure of the oxidation products. The weight gain of AISI 304 stainless steel was about 8 times greater than that of AISI 316 stainless steel, and AISI 316 stainless steel reached the breakdown point about 40 times more slowly than AISI 304 stainless steel. In both stainless steels, reaching the breakdown point meant the loss of the protective oxide scale of Cr2O3, but whereas in AISI 304 stainless steel the Cr2O3scale totally disappeared and exclusively Fe2O3was formed, in AISI 316 stainless steel some Cr2O3persisted and Fe3O4was mainly formed, which means that AISI 316 stainless steel is more resistant to oxidation after the breakdown.


Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1845
Author(s):  
Francesca Borgioli ◽  
Emanuele Galvanetto ◽  
Tiberio Bacci

Low-temperature nitriding allows to improve surface hardening of austenitic stainless steels, maintaining or even increasing their corrosion resistance. The treatment conditions to be used in order to avoid the precipitation of large amounts of nitrides are strictly related to alloy composition. When nickel is substituted by manganese as an austenite forming element, the production of nitride-free modified surface layers becomes a challenge, since manganese is a nitride forming element while nickel is not. In this study, the effects of nitriding conditions on the characteristics of the modified surface layers obtained on an austenitic stainless steel having a high manganese content and a negligible nickel one, a so-called nickel-free austenitic stainless steel, were investigated. Microstructure, phase composition, surface microhardness, and corrosion behavior in 5% NaCl were evaluated. The obtained results suggest that the precipitation of a large volume fraction of nitrides can be avoided using treatment temperatures lower than those usually employed for nickel-containing austenitic stainless steels. Nitriding at 360 and 380 °C for duration up to 5 h allows to produce modified surface layers, consisting mainly of the so-called expanded austenite or gN, which increase surface hardness in comparison with the untreated steel. Using selected conditions, corrosion resistance can also be significantly improved.


2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Philip J. Maziasz ◽  
John P. Shingledecker ◽  
Neal D. Evans ◽  
Michael J. Pollard

Oak Ridge National Laboratory and Caterpillar (CAT) have recently developed a new cast austenitic stainless steel, CF8C-Plus, for a wide range of high-temperature applications, including diesel exhaust components and turbine casings. The creep-rupture life of the new CF8C-Plus is over ten times greater than that of the standard cast CF8C stainless steel, and the creep-rupture strength is about 50–70% greater. Another variant, CF8C-Plus Cu/W, has been developed with even more creep strength at 750–850°C. The creep strength of these new cast austenitic stainless steels is close to that of wrought Ni-based superalloys such as 617. CF8C-Plus steel was developed in about 1.5 years using an “engineered microstructure” alloy development approach, which produces creep resistance based on the formation of stable nanocarbides (NbC), and resistance to the formation of deleterious intermetallics (sigma, Laves) during aging or service. The first commercial trial heats (227.5 kg or 500 lb) of CF8C-Plus steel were produced in 2002, and to date, over 27,215 kg (300 tons) have been produced, including various commercial component trials, but mainly for the commercial production of the Caterpillar regeneration system (CRS). The CRS application is a burner housing for the on-highway heavy-duty diesel engines that begins the process to burn-off particulates trapped in the ceramic diesel particulate filter (DPF). The CRS/DPF technology was required to meet the new more stringent emissions regulations in January, 2007, and subjects the CRS to frequent and severe thermal cycling. To date, all CF8C-Plus steel CRS units have performed successfully. The status of testing for other commercial applications of CF8C-Plus steel is also summarized.


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