High-alloy Stainless Steels Research Articles

Dynamic shear resistance and its dependence on geometrical imperfection of high entropy Cantor alloy and BJAM 316L stainless steel

This paper examines the adiabatic shear resistance of recently popular Cantor alloy and Binder Jetting Additive Manufacturing (BJAM) 316L, with emphasis on their dependence on geometrical imperfection. A series of shear tests were conducted by using the long Split Hopkinson bar and shear compression specimen (SCS). Both alloys present strain rate dependent shear behaviour with the large dynamic shear failure strain of about 104 %–132 %. Microstructural characterizations reveal that both Cantor and BJAM 316L alloys fail by adiabatic shear band. Introduced by the varying notch root radius, the sharpness significantly affects the dynamic shear resistance of the Cantor and BJAM 316L alloys. The linear functions are proposed to describe the drop of critical strain and energy density with the designed inverse root radius.

Case Study: Innovative Sand-Screen Technology Resolves Offshore Nigeria Water-Injection Issues

_ During continuous injection, reservoir solids usually remain within the reservoir. However, prolonged or abrupt well shut ins can trigger intense transient flow phenomena like water hammer, backflow, and crossflow, causing fines and matrix sands to migrate and accumulate in the wellbore (SPE 187103). As a result, the accumulation of debris can markedly reduce structural integrity and the overall long-term viability of enhanced oil recovery (EOR) from the injection wells. This issue had become particularly evident in an offshore field situated in the southern region of the Niger Delta. Over time, buildup in the well led to a substantial decrease in injection rates, which had significantly shortened the operational lifespan of the wells to just a few years at the anticipated injection rates. Various remediation technologies were attempted, such as tubing-installed valve and backflow-restrictor technology but both proved ineffective in resolving annular-flow and crossflow issues. To prevent potentially expensive and complex interventions, sidetracking, or wellbore abandonment, further analyses by the operator, SNEPCo, concluded that an effective solution necessitated deployment as close to the sandface within the injector wells as possible. The Cascade system, a check-valve system developed by TAQA Well Completions (formerly Tendeka), was then successfully deployed in three wells to maintain the required injection volumes for efficient pressure maintenance and reservoir sweep. Non-Return Valve Screen Technology Establishing a reliable flow-control system for the lower completion requires engineering the check-valve components to seamlessly integrate within the sand-control screens for deployment across multiple zones of the injection tubing. The non-return valve (NRV) employs a three-component design comprising a valve body, valve insert, and ball. Ball check valves are installed on the screen base pipe under a shroud that allows the injection of fluid into the reservoir and prevents any backflow from the reservoir during shut ins. The system features a flow-control check valve integrated within traditional sand screens that do not alter completion geometry (Fig. 1). With a metal-to-metal seal, it essentially isolates fluid in the completion annulus and locks injection water into the formation. The NRV has been designed to handle a variety of well conditions including erosion, plugging, temperature, and repeated checking cycles. All flow-control device components are manufactured with high-alloy stainless steel and tungsten carbide components to resist tortuous downhole conditions for up to 15 years. Developed in 2018, more than 2,000 of the valves have already been successfully installed in several wells globally. As this new sand-control technology can autonomously and immediately isolate the reservoir from the wellbore during shut ins, the technology offers additional benefits. - Nonintrusive nature for intervention tools - Unhindered access to the lower completion sandface during injection and intervention - Durability throughout the well’s operational life - Compatibility with openhole standalone screens, gravel- pack completions, direct wrap or metal mesh screens - Cost-effectiveness compared to other options

Dissimilar laser welding of CrMnFeCoNi high entropy alloy and 316LN stainless steel for cryogenic application

The microstructure and mechanical properties of dissimilar laser beam welded joint between CrMnFeCoNi alloy and 316LN stainless steel was investigated. The results showed that the defect-free dissimilar joint was obtained by laser beam welding. The ultimate strength of the welded joints can reach ∼90% of the base materials at both room and cryogenic temperatures. The deformation substructure mainly consisted of planar dislocation, the stacking faults and the dissociation of stacking faults into nanotwins. The volume fraction of the nanotwins was increasing at cryogenic temperature. The hardness fluctuates greatly in welded joint and the lowest hardness was located at fusion zone near the fusion line. The fracture of the welded joint was located at the fusion zone in consistence with the lowest hardness area. It is mainly attributed to the coarse grain and stress concentration at this area.

Pitting corrosion on highly alloyed stainless steels in dilute sulphuric acid containing sodium chloride

Stainless steels are widely used in industrial assets and equipment. Despite their good corrosion resistance under a wide range of operating conditions, there is the possibility of pitting corrosion in the presence of chlorides. However, very few studies have identified the safe operating conditions for various high-alloyed stainless steel grades by comparing their pitting susceptibility. In this research, the susceptibility to pitting attack of five stainless steels with austenitic and duplex microstructures was examined in dilute sulphuric acid solution with varying amounts of NaCl at the temperatures of 50, 90 and 130°C. Based on potentiodynamic polarization scans, none of the test materials underwent pitting corrosion at 50°C, but differences in susceptibility to pitting attack were clear between the test materials and NaCl concentrations at the temperature of 90°C, and further temperature increase facilitated uniform corrosion. 28-day immersion tests at 90°C confirmed the pitting susceptibility of duplex grades 1.4662 (PREN 33) and 1.4462 (PREN 35) in the presence of at least 2000 mg/L NaCl, but not the susceptibility of a corresponding austenitic grade 1.4539 (PREN 34). The grades 1.4547 (PREN 43) and 1.4410 (PREN 44) were not susceptible to pitting corrosion under any of the studied conditions. The results from materials microstructural and electrochemical characterization are presented and discussed in this paper.

Microstructure and Cavitation Damage Characteristics of GX40CrNiSi25-20 Cast Stainless Steel by TIG Surface Remelting

Cavitation erosion degrades the surface of engineering components when the material is exposed to turbulent fluid flows. Under conditions of local pressure fluctuations, a nucleation of gas or vapor bubbles occurs. If the pressure suddenly drops below the vapor pressure, these bubbles collapse violently when subjected to higher pressure. This collapse is accompanied by the sudden flow of the liquid, which is manifested by stress pulses capable of causing plastic deformations on solid surfaces. Repeating these stress conditions can cause material removal and ultimately failure of the component itself. The present study aims to reduce the negative impact of this phenomenon on the mechanical systems components, using the TIG local surface remelting technique. Cavitation erosion tests were performed in accordance with the ASTM G32-2016 standard on samples taken from a cast high-alloy stainless steel. The alloy response for each melting current value was investigated by measuring mass loss as a function of cavitation attack time and by analyzing the damaged surfaces using optical and scanning electron microscopes. It was highlighted that the TIG remelted layers provide an increase in cavitation erosion resistance of 5-6 times as a consequence of the fine graining and microstructure induced by the technique applied.

Microstructural, textural, and residual stress evolution alongside the magnetic properties through isothermal static recrystallization of cold-drawn Fe–Cr–Si–S–C ferritic high-alloy stainless steel and by JMAK modelling

The evolution of microstructures, textures, and residual stresses scale of cold-drawn (CD) 18%Cr ferritic stainless steels (FSS) round bars under isothermal static recrystallization annealing are investigated. As for determination of the new grains' formation, the size, growth, and orientation, as well as the nucleation of grains, alongside revealing the recrystallization fractions are studied by a mixed experimental and theoretical work. The recrystallization kinetics are calculated according to the Johnson-Mehl-Avrami-Kolmogorov theory. Electron backscatter diffraction (EBSD) analyses are applied for the actual specimens of an industrial wire drawing process with 20 and 35% reduction rates. The heat treatment has been implemented at three different set ratio temperatures of 0.65, 0.68, and 0.71, defining as a ratio between the temperatures of annealing and melting point (TRAM). According to the results, the nucleation is occurred at faster incubation time with higher temperature and reduction rate. The grain average size (AGS) increases gradually whereas the temperature increases. This is while the 0.71TRAM-scale annealed samples illustrate finer and more equiaxed recrystallized grains. Following recovery, recrystallized grains, and the grain growth, the overall varied AGS of 27–86 μm in the core region are achieved. Moreover, the JMAK model agrees well with the obtained experimental data. All in all, this 18Cr-FSS material is taken into account for the optimal industrial annealing production as well as the targeted material selection of the market applications. It is observed that the higher recrystallization leads the higher magnetic permeability, lower coercivity, and lower residual stresses compared to the unheated specimens.

Americium-beryllium shield container optimization with new high alloyed stainless steel and composite material using MCNPX code

In this paper the goal is to optimize a shield for the americium-beryllium radioactive source, which generates a mixed neutron and gamma-ray radiation field, using two different materials designed with simultaneous moderation and absorption of neutrons and gamma-ray shielding in mind: a new type of stainless steel and epoxy resin (C21H25ClO5) composite with a 40% NiO additive. For this purpose, MCNPX was used and the equivalent dose rate for both types of radiation was calculated. After the optimization process, the shield volume experienced a 54% reduction while its weight, due to the use of a steel alloy, was increased by 3.56 %. At a distance of 1 m from the center of the source, the equivalent dose rate was reduced by 10.98% in comparison to that of the original system.

Determined to the microstructural and mechanical properties of deposits made of high alloy steels used in the construction of environmentally friendly hydraulic turbines

Research on hydraulic turbines, regardless of type, has shown that all materials used in the manufacture of parts that are components of the flow path, working in the same conditions, are subject to hydro-abrasive wear, in different proportions. The most attacked components are the blades and the chambers of the hydraulic turbines. In this paper are studied materials used in the construction of hydraulic turbine blades that have been previously deposited by the method of the electro-spark deposition with tungsten carbide (WC) electrodes. These deposits were made in order to offer the turbine blades as high a reliability as possible but also to be able to use such hydraulic turbines in the harshest conditions and which could provide as much energy as possible. A high-alloy stainless steel containing Cr and Ni was used as the basic material for the study. The raw samples from a hydraulic turbine blade and those submitted were analyzed both structurally using the optical stereomicroscope and the SEM electron microscope and chemically using the EDX probe. High alloy steel based on Cr and Ni but also WC deposits will be subjected to mechanical tests to see how they resist wear.

Ferritic-induced high-alloyed stainless steel produced by laser powder bed fusion (L-PBF) of 2205 duplex stainless steel: Role of microstructure, corrosion, and wear resistance

Stainless steels are dominant in application where combination of corrosion and mechanical resistances are requested. They have gained scientific attention in additive manufacturing (AM) field, and stainless steel products produced by AM find use in a wide array of applications. This study aims to evaluate the microstructure, the wear and corrosion resistances of a high-alloyed ferritic-induced stainless steel (FSS) obtained by laser powder bed fusion (L-PBF), from a duplex stainless steel (DSS) precursor, SAF 2205, used to produce gas-atomized powders. No heat treatment was applied to the ferritic-induced L-PBF stainless steel to restore the duplex structure. The L-PBF FSS was dense and high alloyed with Cr, Mo, and N (pitting resistance equivalent number, PREn, ~33), presenting a negligible corrosion current density in the order of 10−7 A.cm−2, with an enlarged passivation window ~ 1.2 V with respect to the corrosion potential, restraining the current density at the passivation plateau below 10−4 A.cm−2. Also, double-loop electrochemical potentiokinetic reactivation (DL-EPR) tests indicated unsensitized L-PBF FSS, with negligible degree of sensitization caused by the cyclic heat input during building up of the specimen. Besides be corrosion-resistant, the L-PBF FSS was hard (290 HV0.5) and wear-resistant against sliding wear, with a reduced specific wear rate of 5 × 10−4 mm3·N−1·m−1. The corrosion resistance of the L-PBF specimen (almost fully ferritic microstructure) was comparable to its hot-rolled precursor that displayed a duplex microstructure, albeit slight inferior. The L-PBF FSS was harder and more wear resistant than the DSS precursor. These results point out to the formation of a new high-alloyed ferritic-induced stainless steel, which are corrosion-resistant in chloride-rich medium and wear resistant in sliding conditions.

Study of the influence of wire metals on dissimilar welds

The aim of this study is to investigate the effect wire metal on microstructure and mechanical properties of dissimilar welds between HSLA-X70 high strength steel alloy and 304L austenitic stainless steel produced by automatic tungsten arc welding (TIG). The weld joints were prepared using E304L, E316L, E2209L, and E7010 wire metal. The mechanical characteristics obtained from hardness, tensile and impact testing, were correlated to the optical and SEM microscopy, to establish a relationship between wire metal composition and the microstructures in different weld regions. It is concluded that E2209 wire metal lead to improve in the resilience characteristics and tenacity with a slight reduction in the ultimate tensile strength and hardness.

High-Temperature Corrosion of Nickel-Based Coatings for Biomass Boilers in Chlorine-Containing Atmosphere

As there is a strong pressure in the EU to reduce CO2 emissions and overall fossil fuel consumption in the energy sector, many boilers are burning biomass instead of traditional fuels (coal, natural gas, oil, etc.). This is mainly due to the EU 2030 energy strategy, which commits Member States to reduce fossil fuel emissions by at least 40% (compared to the 1990 level) and to use at least 32% of renewable energy. The combustion of biomass containing aggressive elements such as chlorine or sulfur causes serious damage to various boiler components, with negative impacts such as reduced boiler lifetime, increased investments and maintenance costs, reduced availability, and others. These problems occur mainly in plants/boilers designed to burn coal and redesigned to burn biomass (straw, wood chips, wood pellets, etc.). In this paper, the corrosion resistance of heat coatings determined in long-term laboratory tests in an environment specifically corresponding to biomass flue gas is presented. These results can be used to design a suitable modification of existing coal boilers using conventional materials. The aim was to compare three completely different technologies currently available on local markets for the preparation of these coatings—thin wire arc spray (TWAS), high-velocity oxygen fuel (HVOF), and water-stabilized plasma. These coatings were compared with the base material of the boiler tubes—low alloyed steel 16Mo3 and high alloyed austenitic stainless steel AISI 310 as a more expensive option for retrofit. After 5000 h of exposure in an environment containing HCl and SO2, no cracks or structural defects were observed in any of the coatings, and the substrate material showed no signs of oxidation. All the tested coatings had higher corrosion resistance than the 16Mo3 material, and some of them presented a corrosion behavior close to that of the high alloy AISI 310 steel. Structurally and corrosion-wise, the thermally sprayed coating prepared by HVOF technology was the best of all tested materials.

Dry Sliding Wear Behavior of Austenitic Stainless Steel Material by Gas Nitriding Process

In industries, components must operate under extreme conditions such as high load, speed, temperature and chemical environment. Materials are selected according to commercial availability, cost and their properties such as strength, hardness, etc. AISI 904L is a high-alloy stainless steel with low carbon content, poor surface hardness and wear characteristics. Many engineering failures are caused by fatigue, corrosion, and poor wear resistance, begins at the surface level. This causes cracks in the surface, reducing the material’s life. The surfaces of the materials were subjected to severe thermal, chemical, and shock loads. The selected AISI 904L materials for this work were subjected to gas nitriding process and processed with 3 different time parameters such as 12 hours, 18 hours and 24 hours respectively and named as GN1, GN2 and GN3. The treatments were done at a constant temperature of 650°C. Gas nitriding, in comparison to other nitriding processes such as plasma and liquid nitriding, provides good dimensional stability, reduced deformation, and uniform case depth regardless of the size and shape of the specimen. To analyze the wear properties, a pin on a disc machine is used. Finally, metallographic studies were performed by scanning electron microscopy.

ОСОБЕННОСТИ ДУГОВОЙ СВАРКИ СЛОИСТОГО КОРРОЗИОННОСТОЙКОГО МАТЕРИАЛА

The paper shows the demand of the chemical industry for corrosion-resistant materials, as well as the prospects of the creation of laminated metal materials with internal protectors (LMM with IP). The authors offer the architecture and composition of layers of LMM with IP ensuring stable operation within the highly aggressive environment. The study identified the possibility of improving corrosion resistance ten and more times compared to high-alloy austenitic stainless steels. The authors show the efficiency of the application of explosion welding to produce LMM with IP. The paper considers the example of the production of a four-layer material with one internal protector made of low-alloyed, low-carbon steel of the following architecture: 2-mm layers of 12H18N10T + 09G2S + 12H18N10T plates of steel and the base 10-mm layer of 09G2S. The authors developed the process diagrams for performing butt-welded joints of such material, identified special aspects of the formation of its microstructure and properties. To obtain the maps of specific chemical elements distribution in the layers and interlayer boundaries, the authors used the energy-dispersive microanalysis method. Peculiarities of corrosion damage of a welded seam and weld-adjacent area are studied. The study showed the necessity of using a facing layer in a welded seam. Microstructural, X-ray tomographic, and gravity-measuring studies proved the obtained results. To evaluate the quality of welded joint, the authors performed the corrosion tests of a welded seam and weld-adjacent area, carried out visual inspection control and X-ray tomography. The corrosion tests were carried out using 10-% III ferrous chloride water solution. The paper presents the results of the static bending tests of a welded joint. The absence of fracture, lamination, and cracks served as an estimation criterion. The study identified the possibility of obtaining a defect-free welded joint of LMM with IP with high corrosion resistance and advanced mechanical properties.

Evaluation of Microstructure and Mechanical Properties of Explosive-Welded HSLA/304L Steel Bimetallic Plates

High strength low alloy (HSLA) steel 10CrNi3MoV and stainless steel 304L (SS304L) were used to manufacture bimetallic plates by explosive welding. The quality and overall performance of the bimetallic plates were evaluated in terms of microstructure and mechanical properties. Its microstructure, elemental distribution, and phase analysis of the bonding interface were investigated by means of OM, SEM, EDS, and XRD. The mechanical properties of the bimetallic plates were studied by experimental measurements, including tensile tests, shear tests, Charpy impact tests, hardness tests, and then evaluated based on the standards. Experimental evaluation showed out that HSLA 10CrNi3MoV steel and SS304L could be cladded with a good quality of bonding properties by explosive welding. The base material 10CrNi3MoV steel still maintained its inherent excellent mechanical performance, even after undergoing explosive welding process. The functional flyer layer SS304L maintained its corrosion resistance even after undergoing a process of post-weld heat treatment at high temperature 645 °C for 240 min. Shear strength of the bimetallic plates was about 432 MPa more than twice the value required by the standard. The maximum hardness value was obtained near the joint on the side of SS304L, and the minimum one appeared in the middle of the explosive welding interface.

Phase Equilibrium Diagram for Electric Arc Furnace Slag Optimization in High Alloyed Chromium Stainless Steelmaking

The electric arc furnace (EAF) process for steelmaking of Cr and Ni high alloyed stainless steel grades differs significantly from the steelmaking process of carbon steel due to the special raw materials and generally lower oxygen consumption. The special slag chemistry in the EAF process affects slag foaming and refractory wear characteristics due to an increased content of CrOx. A special slag diagram is presented in order to improve monitoring and control of slag compositions for Cr alloyed heats, with special focus on saturation to MgO periclase and dicalcium silicate C2S in order to minimize MgO losses from the refractory lining and to improve slag refining capability by avoidance of stable C2S. With the same diagram different EAF process strategies can be efficiently monitored, either at elevated CaO and basicity with lower spinel concentration and more liquid process slags near C2S saturation or at lower CaO content and basicity with increased spinel concentration and stiffer slags at MgO saturation but certainly no C2S stability. Examples for three industrial EAFs are given.

Stress Corrosion Cracking of High-Pressure Scrubber in Urea Plant: A Case Study

This current work investigates the failure of high pressure (HP) scrubber lining in urea fertilizer production plant after 20 years in service. AISI 316L urea grade (UG) stainless steel scrubber lining was showed severe damage. In order to find out the root cause of failure, cracks were observed by visual inspection together with microstructure examination Chemical analysis of the base metal and corrosion products were analyzed Chemical analysis of the lining base alloy is conformed to the AISI 316L UG. Results revealed existence of chloride assisted stress corrosion cracking (SCC) initiated from pitting formed in the inner surface of the scrubber lining. Corrosion products analysis revealed existence of chloride (Cl-). Localized pitting corrosion is attributed to Cl attack. The expected sources of chloride are water during hydrostatic testing, water vapor during passivation, chloride containing atmosphere during transportation or storage the base alloy in coastal areas and water vapor in carbamate gasses (process fluid). Pits initiated at the lining inner surface act as stress concentration sites assisted SCC initiation. Chloride SCC is caused by simultaneous action of both tensile stresses and a corrosive environment containing chloride. To overcome the scrubber failure, chloride must be eliminated and residual stresses must be controlled. Upgrading the scrubber base alloy using high-alloy duplex stainless steel (Safurex) is highly recommended.

Benefits from improved bath agitation with the RADEX DPP gas purging system during EAF highalloyed and stainless steel production

Modern production processes of high alloyed and stainless steel grades are subject to the cost-optimized production of raw steel or molten combined with high flexibility. Excellent mixing of the steel melt helps to improve mass and heat transfer in the EAF, in order to accelerate the melting of heavy scrap and alloys, decarburization, homogeneous superheating, alloy distribution, and to avoid skull formation and solid remainders that may obstruct tapping. The RADEX DPP system generates customer benefits by improving EAF processes during high-alloyed stainless steel making. The most important effect of the enhanced steel bath mixing besides improved heat transfer and decarburization is a decreased chromium oxidation. Firstly, chromium oxidation is decreased by improving the homogeneous distribution of carbon and chromium in the melt. Secondary, build-up of chromium-containing solids in the EAF hearth and skull formation is decreased by stronger melt movement. The cost savings of both effects economically justify the application of gas purging in EAF stainless steelmaking. Case studies are presented demonstrating the advantages. Ill.7. Ref. 7. Tab. 3.

Formation of Multiple Phase Microstructure and Wear Investigation on Treated AISI 904L SS by Low Temperature Ion Nitriding Process

In industries, components have to operate under extreme prerequisites such as high load, speed, temperature and at a chemical environment. The materials are selected by commercial availability, cost and by considering by their properties like strength, hardness etc. AISI 904L is a high alloy stainless steel with low carbon content material having poor hardness on the surface and negative wear properties. Many of the engineering failures are due to fatigue, corrosion and poor wear resistance which are initiated in its surface. This causes cracks in the surface which reduces the life of the material. Also the surfaces of the materials are caused by severe thermal, chemical and shock loads. Chosen for this work, AISI 904L materials were subjected to plasma or ion - nitriding process and were treated to 3 different timing parameters like 24 hrs, 48 hrs and 72 hrs respectively, maintaining constant temperature of 650oC. Among the availability of other nitriding process like gas and liquid nitriding, plasma nitriding gives good dimensional stability, uniform treatment, less distortion, uniform case depth irrespective towards size and shape of the specimen. For analyzing the wear properties, a pin on disc machine is utilized making the pin to get weared on disc against a load of 100N at a speed of 1000 rpm. Finally the metallographic studies were done by Scanning Electron Microscopic analysis.

Sand-Control Technology for Water Injectors Improves Well Performance

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 192840, “Field-Trial Results for New Sand-Control Technology for Water Injectors,” by Steven Fipke, SPE, Tendeka; J.E. Charles, SPE, Shell; and Annabel Green, Tendeka, prepared for the 2018 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 12–15 November. The paper has not been peer reviewed. In 2014, a research and development (R&D) project was initiated to increase the life expectancy of Gulf of Mexico (GOM) Miocene and Lower Tertiary water-injection (WI) wells, several of which had suffered a severe loss of injectivity within only a few years of completion. The solution was to find a way to prevent fine material from entering the completion while sustaining high injection rates, with no loss of injection pressure or requirement for additional horsepower. A new flow-control device (FCD) and completion system were developed along with intrinsic nonreturn valves (NRVs) that prevent any backflow or crossflow during•shut-ins. Developing the Flow-Control Technology Tubing-deployed injection valves and regulators have been available for many years. However, these cannot address the problem of annular flow. The most-damaging factor in solids production is likely crossflow, wherein differently pressured injection zones can flow between layers inside the tubing or casing annulus. Crossflow can be eliminated only by blocking the flow at the sandface. This solution also would mitigate the damaging effects of water hammer by blocking pressure waves from entering the lower completion. Check-valve components must fit within sand-control screens or be deployed across multiple zones of the injection tubing.• During the R&D phase of the project, researchers used extensive laboratory testing, flow-loop testing, and computational-fluid-dynamics modeling to develop a series of NRV prototypes. The technology was designed to handle a variety of well conditions, including erosion, plugging, temperature, and repeated checking cycles. All FCD components, including the NRV technology, are manufactured with high-alloy stainless steel and tungsten-carbide components to resist tortuous downhole conditions for up to 15 years. FCD prototypes and design iterations were tested over 18 months and a final design was qualified to withstand repetitive pressure- checking cycles reliably at 1,500 psi (and up to 10,000-psi static differential•pressure).• The laboratory testing conducted to finalize the project development stage is described in detail in the complete paper; it consisted of leak-rate, erosion, plugging, and screen-construction stages. One determination of this testing was that the placement of the screen over the FCD joint could cause erosive wear because of the placement of the screen ribs over the valves. An alternative rib wire was designed that could place the FCD between wires without compromising the strength of the screen. With laboratory and workshop testing completed by early 2017, the focus of the project shifted to identifying and organizing a field trial for the new technology in a low-cost, low-risk environment.

The Role of Surface Texture on the Corrosion Fatigue Behavior of High Alloyed Stainless Steel Exposed to Saline Aquifer Water Environment

Corrosion fatigue specimen with different surfaces (technical surfaces after machining and polished surfaces) of high alloyed martensitic stainless steel X46Cr13 (1.4043) and duplex stai nless steel X2CrNiMoN22 3 2 (1.4462) were compared at load amplitudes from 175 MPa to 325 MPa in the geothermal brine of the N orthern German Basin at 98 °C. Surface corrosion layers and pits reveal carbonate corrosion products on the surface such as FeCO 3 and FeOOH as the main precipitation phases with no dependence on the original surface roughness . At high stress amplitudes above 275 MPa technical surfaces (P50% at σa 300 MPa=5 × 10 5 ) resulted in more cycles to failure than polished (P50% at σa 300 MPa=1.5 × 10 5 ). The greater slope coefficient for technical surfaces k = 19.006 compared to polished surfaces k =8.78 demonstrate s earlier failure at given stress amplitude σa .