A Model for the Hydrogen Diffusion in Dual-Phase Stainless Steels for High-Pressure Applications

2021 ◽  
Author(s):  
Marco Beghini ◽  
GIUSEPPE MACORETTA ◽  
Bernardo Disma Monelli ◽  
Renzo Valentini ◽  
Linda Bacchi
Keyword(s):  
High Pressure ◽  
Stainless Steels ◽  
Hydrogen Diffusion ◽  
Dual Phase

Comparison of Stress Corrosion Cracking of High-Chromium Stainless Steels

2021 ◽  
Vol 73 (07) ◽  
pp. 53-54
Author(s):  
Chris Carpenter
Keyword(s):  
High Pressure ◽  
Tensile Strength ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Stainless Steels ◽  
Electrochemical Measurement ◽  
Corrosion Cracking ◽  
High Chromium ◽  
High Pressure High Temperature ◽  
Elongation To Failure

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper NACE 2020-14695, “Comparison of Stress Corrosion Cracking Behavior of Fe13Cr5Ni- and Fe17Cr5.5Ni-Based High-Chromium Stainless Steels in High-Pressure/High-Temperature CO2 Environments,” by Yameng Qi, Zhonghua Zhang, and Chunxia Zhang, Baoshan Iron and Steel, prepared for the 2020 NACE International Corrosion Conference and Exposition, Houston, 14–18 June. The paper has not been peer reviewed. Stress corrosion cracking (SCC) of Fe13Cr5Ni- and Fe17Cr5.5Ni-based alloys in high-pressure/high-temperature (HP/HT) carbon dioxide (CO2) environments was investigated through slow-strain-rate tests (SSRTs) and electrochemical methods. The results show that a remarkable decrease in tensile strength and elongation to failure was observed when testing in a CO2 environment compared with that of air. Fe17Cr5.5Ni-based alloys possessed better SCC resistance than Fe13Cr5Ni-based alloys. The better SCC resistance of the former could be attributed to good repassivation capacity and pitting-corrosion resistance induced by the increase in chromium (Cr) and nickel (Ni) content. Introduction When service temperature exceeds 150°C, SCC resistance of Fe13Cr5Ni-based alloys could become an issue. Compared with Fe13Cr5Ni-based alloys, 22Cr duplex stainless steel has an excel-lent performance when exposed to temperatures over 150°C and stable SCC resistance in HP/HT CO2 environments. However, the cost of 22Cr duplex stainless steel is extremely high. Experimental Procedure Fe13Cr5Ni- and Fe17Cr5.5Ni-based alloys were produced by the authors’ research institute. The materials were in a quenched and tempered state. For micrographic observation, each specimen was ground with 2,000-grit carbide silicon paper and polished with 1.2-µm diamond paste. They were then degreased with acetone and etched with hydrochloric ferric chloride solution (a mixture of 5-g ferric chloride, 25-mL hydrochloric acid, and 25-mL ethanol). The steel microstructures were characterized using an optical micro-scope. The micrograph in Fig. 1a for the F-13Cr5Ni-based alloys shows a martensite phase with no notable second phases. Fe17Cr5.5Ni alloys possess long strip ferrite and martensite phases (Fig. 1b). For SSRTs, smooth tensile specimens with a gauge length of 25.4 mm and a diameter of 3.81 mm were prepared. The specimens were cut from the Fe13Cr5Ni- and Fe17Cr5.5Ni-based alloys into an 8-mm-thick, 12-mm-outer- diameter disc for electrochemical measurement. All specimens were polished to a 1,200-grit surface finish, degreased with acetone, cleansed with distilled water, and dried in air. SSRT and electrochemical-measurement procedures are detailed in the complete paper. Results SCC Susceptibility. As expected, tensile strength and elongation to failure of Fe13Cr5Ni- and Fe17Cr5.5Ni-based alloys deteriorated in HP/HT CO2 environments. Compared with an environment of air, the elongation to failure of Fe13Cr5Ni- and Fe17Cr5.5Ni-based alloys in HP/HT CO2 environments decreased by approximately 30 and 25%, respectively. In addition, tensile strength and elongation to failure of Fe17Cr5.5Ni-based alloys were greater than those of Fe13Cr5Ni-based alloys. Elongation, reduction in area, and time to failure of Fe17Cr5.5Ni-based alloys were found to be much higher than that of Fe13Cr5Ni-based alloys in HP/HT CO2 environments. It can be concluded that Fe17Cr5.5Ni alloys possess better SCC resistance than Fe13Cr5Ni alloys in these environments.

Producing HP Pump Barrels Utilizing Powder Metallurgy and Hot Isostatic Pressing

2009 ◽  
Author(s):  
Martin Bjurstro¨m ◽  
Carl-Gustaf Hjorth
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Stainless Steels ◽  
Hot Isostatic Pressing ◽  
Austenitic Stainless Steels ◽  
Pressure Vessels ◽  
Uniform Structure ◽  
Isostatic Pressing ◽  
Near Net Shape ◽  
Hip Process

The fabrication of near net shape powder metal (PM) components by hot isostatic pressing (HIP) has been an important manufacturing technology for steel and stainless steel alloys since about 1985. The manufacturing process involves inert gas atomization of powder, 3D CAD capsule design, sheet metal capsule fabrication and densification by HIP in very large pressure vessels. Since 1985, several thousand tonnes of parts have been produced. The major applications are found in the oil and gas industry especially in offshore applications, the industrial power generation industry, and traditional engineering industries. Typically, the components replace castings, forgings and fabricated parts and are produced in high alloy grades such as martensitic steels, austenitic stainless steels, duplex (ferritic/austenitic) stainless steels and nickel based superalloys. The application of PM/HIP near net shapes to pump barrels for medium to high pressure use has a number of advantages compared to the traditional forging and welding approach. First, the need for machining of the components is reduced to a minimum and welding during final assembly is reduced substantially. Mechanical properties of the PM/HIP parts are isotropic and equal to the best forged properties in the flow direction. This derives from the fine microstructure using powder powder and the uniform structure from the HIP process. Furthermore, when using the PM HIP process the parts are produced near net shape with supports, nozzles and flanges integrated. This significantly reduces manufacturing lead-time and gives greater design flexibility which improves cost for the final component. The PM HIP near net shape route has received approval from ASTM, NACE and API for specific steel, stainless steel and nickel base alloys. This paper reviews the manufacturing sequence for PM near net shapes and discusses the details of several successful applications. The application of the PM/HIP process to high pressure pump barrels is highlighted.

Development of New Material Testing Apparatus in High-Pressure Hydrogen and Evaluation of Hydrogen Gas Embrittlement of Metals

2007 ◽  
Author(s):  
Seiji Fukuyama ◽  
Masaaki Imade ◽  
Kiyoshi Yokogawa
Keyword(s):  
High Pressure ◽  
Stainless Steels ◽  
Pressure Vessel ◽  
Austenitic Stainless Steels ◽  
Material Testing ◽  
Hydrogen Gas ◽  
Stage Ii ◽  
Fuel Cell Vehicle ◽  
Stage Iii ◽  
Pressure Hydrogen

A new type of apparatus for material testing in high-pressure gas of up to 100 MPa was developed. The apparatus consists of a pressure vessel and a high-pressure control system that applies the controlled pressure to the pressure vessel. A piston is installed inside a cylinder in the pressure vessel, and a specimen is connected to the lower part of the piston. The load is caused by the pressure difference between the upper room and the lower room separated by the piston, which can be controlled to a loading mode by the pressure valves of the high-pressure system supplying gas to the vessel. Hydrogen gas embrittlement (HGE) and internal reversible hydrogen embrittlement (IRHE) of austenitic stainless steels and iron- and nickel-based superalloys used for high-pressure hydrogen storage of fuel cell vehicle were evaluated by conducting tensile tests in 70 MPa hydrogen. Although the HGE of these metals depended on modified Ni equivalent, the IRHE did not. The HGE of austenitic stainless steels was larger than their IRHE; however, the HGE of superalloys was not always larger than their IRHE. The effects of the chemical composition and metallic structure of these materials on the HGE and IRHE were discussed. The HGE of austenitic stainless steels was examined in 105 MPa hydrogen. The following were identified; SUS304: HGE in stage II, solution-annealed SUS316: HGE in stage III, sensitized SUS316: HGE in stage II, SUS316L: HGE in FS, SUS316LN: HGE in stage III and SUS310S: no HGE.

Producing HP Pump Barrels Utilizing Powder Metallurgy and Hot Isostatic Pressing

2009 ◽  
Author(s):  
Martin Bjurstro¨m ◽  
Carl-Gustaf Hjorth
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Stainless Steels ◽  
Hot Isostatic Pressing ◽  
Austenitic Stainless Steels ◽  
Pressure Vessels ◽  
Uniform Structure ◽  
Isostatic Pressing ◽  
Near Net Shape ◽  
Hip Process

The fabrication of near net shape powder metal (PM) components by hot isostatic pressing (HIP) has been an important manufacturing technology for steel and stainless steel alloys since about 1985. The manufacturing process involves inert gas atomization of powder, 3D CAD capsule design, sheet metal capsule fabrication and densification by HIP in very large pressure vessels. Since 1985, several thousand tonnes of parts have been produced. The major applications are found in the oil and gas industry especially in offshore applications, the industrial power generation industry, and traditional engineering industries. Typically, the components replace castings, forgings and fabricated parts and are produced in high alloy grades such as martensitic steels, austenitic stainless steels, duplex (ferritic/austenitic) stainless steels and nickel based superalloys. The application of PM/HIP near net shapes to pump barrels for medium to high pressure use has a number of advantages compared to the traditional forging and welding approach. First, the need for machining of the components is reduced to a minimum and welding during final assembly is reduced substantially. Mechanical properties of the PM/HIP parts are isotropic and equal to the best forged properties in the flow direction. This derives from the fine microstructure using powder powder and the uniform structure from the HIP process. Furthermore, when using the PM HIP process the parts are produced near net shape with supports, nozzles and flanges integrated. This significantly reduces manufacturing lead-time and gives greater design flexibility which improves cost for the final component. The PM HIP near net shape route has received approval from ASTM, NACE and API for specific steel, stainless steel and nickel base alloys. This paper reviews the manufacturing sequence for PM near net shapes and discusses the details of several successful applications. The application of the PM/HIP process to high pressure pump barrels is highlighted.

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