scholarly journals Temperature Effects on Fracture Thresholds of Hydrogen Precharged Stainless Steel Welds

2017 ◽  
Author(s):  
Joseph A. Ronevich ◽  
Chris San Marchi ◽  
Dorian K. Balch
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
Room Temperature ◽  
Nickel Content ◽  
Austenitic Stainless Steels ◽  
Total Elongation ◽  
Fracture Testing ◽  
Fracture Threshold ◽  
Gas Tungsten Arc ◽  
Steel Welds

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.

scholarly journals Fracture Threshold Measurements of Hydrogen Precharged Stainless Steel Weld Fusion Zones and Heat Affected Zones

2015 ◽  
Author(s):  
Joseph A. Ronevich ◽  
Brian P. Somerday ◽  
Chris W. San Marchi ◽  
Dorian K. Balch
Keyword(s):  
Stainless Steel ◽  
Fusion Zone ◽  
Stainless Steels ◽  
Heat Affected Zone ◽  
Austenitic Stainless Steels ◽  
Hydrogen Gas ◽  
Gas Tungsten Arc ◽  
Hydrogen Assisted Cracking ◽  
Point Bend ◽  
Subcritical Cracking

Austenitic stainless steels are used in hydrogen environments because of their generally accepted resistance to hydrogen embrittlement; however, hydrogen-assisted cracking can occur depending on the microstructures or composition of the stainless steel. One area that has not been well researched is welds and in particular heat affected zones. The goal of this work was to measure the subcritical cracking susceptibility of hydrogen precharged gas tungsten arc (GTA) welds in forged stainless steels (21Cr-6Ni-9Mn and 304L). Welds were fabricated using 308L filler metal to form 21-6-9/308L and 304L/308L weld rings, and subsequently three-point bend specimens were extracted from the fusion zone and heat affected zone and precharged in high-pressure hydrogen gas. Crack growth resistance curves were measured in air for the hydrogen precharged fusion zones and heat affected zones under rising-displacement loading, revealing significant susceptibility to subcritical cracking. Fracture thresholds of 304L/308L welds were lower than 21-6-9/308L welds which was attributed to higher ferrite fractions in 304L/308L since this phase governed the crack path. Fracture thresholds for the heat affected zone were greater than the fusion zone in 21-6-9/308L which is likely due to negligible ferrite in the heat affected zone. Modifications to the weld joint geometry through use of a single-J design were implemented to allow consistent testing of the heat affected zones by propagating the crack parallel to the fusion zone boundary. Despite low hydrogen diffusivity in the austenitic stainless steels, effects of displacement rates were observed and a critical rate was defined to yield lower-bound fracture thresholds.

Precipitation Strengthening Of Rapidly Solidified Austenitic Stainless Steels

1983 ◽  
Vol 28 ◽  
Author(s):  
J. Megusar ◽  
A. Chaudhry ◽  
D. Imeson ◽  
N. J. Grant
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
Room Temperature ◽  
Mechanical Stability ◽  
Austenitic Stainless Steels ◽  
Titanium Content ◽  
Recrystallization Temperature ◽  
316 Stainless Steel ◽  
Room Temperature Yield Strength ◽  
Rapidly Solidified

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.

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.

ATI 310S

Alloy Digest ◽  
2020 ◽  
Vol 69 (10) ◽  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Stainless Steels ◽  
Room Temperature ◽  
Austenitic Stainless Steels ◽  
Heat Treating ◽  
Resistance To Oxidation ◽  
The Common ◽  
Type 304 ◽  
Room Temperature Strength

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.

ARMCO NITRONIC 40

Alloy Digest ◽  
1990 ◽  
Vol 39 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Stainless Steels ◽  
Room Temperature ◽  
Austenitic Stainless Steels ◽  
Heat Treating ◽  
Advanced Materials ◽  
High Toughness ◽  
Temperature Performance ◽  
Room Temperature Yield Strength

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.

Discussion on Fatigue Design Curves for Stainless Steels

2011 ◽  
Author(s):  
Jussi Solin ◽  
Sven Reese ◽  
Wolfgang Mayinger
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
Room Temperature ◽  
Austenitic Stainless Steels ◽  
Additional Research ◽  
Design Curve ◽  
Fatigue Design ◽  
Contradictory Data ◽  
Relevant Material

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.

scholarly journals Evaluating the Resistance of Austenitic Stainless Steel Welds to Hydrogen Embrittlement

2019 ◽  
Author(s):  
Joseph Ronevich ◽  
Chris San Marchi ◽  
Dorian K. Balch
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stainless Steels ◽  
Extreme Environments ◽  
Base Material ◽  
Austenitic Stainless Steels ◽  
Hydrogen Gas ◽  
Gas Leakage ◽  
Toughness Testing ◽  
Steel Welds

Abstract Austenitic stainless steels are used extensively in hydrogen gas containment components due to their known resilience in hydrogen environments. Depending on the conditions, degradation can occur in austenitic stainless steels but typically the materials retain sufficient mechanical properties within such extreme environments. In many hydrogen containment applications, it is necessary or advantageous to join components through welding as it ensures minimal gas leakage, unlike mechanical fittings that can become leak paths that develop over time. Over the years many studies have focused on the mechanical behavior of austenitic stainless steels in hydrogen environments and determined their properties to be sufficient for most applications. However, significantly less data have been generated on austenitic stainless steel welds, which can exhibit more degradation than the base material. In this paper, we assess the trends observed in austenitic stainless steel welds tested in hydrogen. Experiments of welds including tensile and fracture toughness testing are assessed and comparisons to behavior of base metals are discussed.

Microstructure Analysis of Post Weld Aging in Duplex Stainless Steel Welds

2013 ◽  
Vol 717 ◽  
pp. 210-214
Author(s):  
Santirat Nansa-Arng ◽  
Prachya Peasura
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Phase Analysis ◽  
Stainless Steels ◽  
Heat Affected Zone ◽  
Parent Phase ◽  
Austenitic Stainless Steels ◽  
Ferrite Phase ◽  
Structural Applications ◽  
Steel Welds

Duplex stainless steel (DSS) offers an alternative to the austenitic stainless steels especially at temperatures between –50 and 300°C and is suitable for structural applications. The research was study the effect of post weld aging (PWA) parameters on microstructure in heat affected zone. The specimen was duplex stainless steel (DSS) UNS31803 which thickness of 10 mm. The PWA sample were tested the microstructure and phase analysis. The factors used in this study were PWA temperature of 650, 750, and 850๐C with PWA time of 1, 2, 4 and 8 hours. The welded specimens were tested by microstructure and phase analysis testing according to ASTM E3-11 code. The result showed that both of PWA temperature and PWA time can greatly affect microstructure and phase analysis in heat affected zone (HAZ). The ferrite that was austenite with a grain and an austenite scattered throughout. The microstructures of PWA 650 °C with PWA 1, 2, 4 and 8 hours in ferrite phase which ferrite phase was not different. The widmanstätten structures were observed high PWA temperatures were also distributed at grain. At high PWA temperature, ferrite at the grain boundary tended to decrease. Moreover excessive aging temperature can result in increasing austenite intensity and size in parent phase. Definitely, at high PWA temperature and time, over-aging of HAZ resulted in corrosion resistance reduce.

ALZ 316

Alloy Digest ◽  
1999 ◽  
Vol 48 (8) ◽  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Austenitic Stainless Steel ◽  
Physical Properties ◽  
Tensile Properties ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Heat Treating

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 0Cr25Ni6Mo3CuN

Alloy Digest ◽  
1998 ◽  
Vol 47 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Temperature Performance ◽  
Steel Research ◽  
Oil Refinement

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.

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