High Strength Duplex Stainless Steel Research Articles

Explosive welding of Al alloys and high strength duplex stainless steel by controlling energetic conditions

Abstract In this study, Al alloys and high strength duplex stainless steel plates were welded using explosive welding technology. Compared with the direct welding method, the use of an interlayer can reduce kinetic energy dissipated during the welding of dissimilar metals, which reduce the thickness of excessive melting layer to achieve high-quality welding. Different interface morphologies were observed under different welding parameters. In particular, a flat welding interface was observed which differed from conventional explosive welding, when the velocity of the flyer plate was relatively less. The tensile shear tests and bending tests demonstrated that the welding strength was high when high-quality welding was achieved. The smoothed particle hydrodynamics (SPH) numerical model was used to simulate the welding process, and the simulated interface morphologies were consistent with the experimental results. The jet velocity, temperature, and strain near the interface and the velocity and collision angle of the interlayer at the collision point were calculated using the numerical simulations. As per the discussion based on the weldability window, the difficulty of achieving direct welding between Al alloys and duplex stainless steel was demonstrated. Using weldability window to analysis tri-metallic joints, the analysis revealed why using an interlayer can make the welding easily. Further, a method to realize interlayer welding is presented.

Transfer and Development Length of High-Strength Duplex Stainless Steel Strand in Prestressed Concrete Piles

Transfer and Development Length of High-Strength Duplex Stainless Steel Strand in Prestressed Concrete Piles

Effects of hydrogen assisted stress corrosion on damage tolerance of a high-strength duplex stainless steel wire for prestressing concrete

The study brings new insights on the hydrogen assisted stress corrosion on damage tolerance of a high-strength duplex stainless steel wire which concerns its potential use as active reinforcement for concrete prestressing. The adopted procedure was to experimentally state the effect of hydrogen on the damage tolerance of cylindrical smooth and precracked wire specimens exposed to stress corrosion cracking using the aggressive medium of the standard test developed by FIP (International Prestressing Federation). Stress corrosion testing, mechanical fracture tests and scanning electron microscopy analysis allowed the damage assessment, and explain the synergy between mechanical loading and environment action on the failure sequence of the wire. In presence of previous damage, hydrogen affects the wire behavior in a qualitative sense, consistently to the fracture anisotropy attributable to cold drawing, but it does not produce quantitative changes since the steel fully preserves its damage tolerance.

Use of Advanced Austenitic and Duplex Stainless Steels for Applications in Oil & Gas and Process Industry

Stainless steels are widely used in the Oil & Gas and chemical process industry. This group of materials is today available in a large variety of alloy compositions, and practically all product forms needed for a construction are available. A historical view and application examples are given on the stainless steel evolution, from the standard grades used in chemical processes to todays most advanced applications in the chemical and oil & gas industry, where demands on reliable and long lasting solutions are necessary. The influence of alloying elements on the properties and manufacturability is described. The chemical industry is a very wide definition of a large group of industries with very different products, from plastics and organic acids to fertilizers, drugs and pesticides. Applications of stainless steels within the chemical industry are described. The first example is organic acids, where the use of high alloyed duplex stainless steels such as UNS S32205 and UNS S32750 have been successful. Another example is phosphoric acid applications, where the aggressiveness of the process solution depends very much on the fluoride and chloride content of the rock phosphate. In sulfuric acid, the material of construction is very much dependent on the acid concentration and temperature. Nitric acid is another common fertilizer acid which is highly oxidizing, and thereby demands stainless steels with high chromium content but with low molybdenum contents. The Oil & Gas industry uses very high quantities of carbon steel and stainless steel in their constructions. The oil wells are defined as sweet when the well contains carbon dioxide and no substantial amounts of hydrogen sulfide, when there is hydrogen sulfide present in the well, the wells are defined as sour. An overview on materials depending on the application is given. In subsea applications, hydraulic control lines (umbilicals) are used for control of valves and for methanol injection in subsea platforms. UNS S32750 is a high strength duplex stainless steel which today is the first choice for umbilicals and has been chosen for a very large amount of umbilical projects worldwide. The newly developed hyper duplex stainless steels with a combination of even higher corrosion resistance and strength are introduced for applications in oil-gas industry. The possibilities with stainless steels are endless, and new alloys are constantly being developed to meet industrial challenges of today and in the future. By choosing the right stainless steel grade, it is possible to find a solution to almost all challenges in the Oil & Gas and Process industry.

ALLEGHENY LUDLUM ALLOY 255

Abstract Allegheny Ludlum alloy 255 is a high-strength duplex stainless steel. It combines high mechanical strength, ductility, and hardness with excellent resistance to corrosion and erosion. Under most conditions of service, its corrosion resistance is superior to that of the fully austenitic AISI type 304, 316, and 317L stainless steels. Its many uses include marine scrubbers, desalination equipment, sulfuric acid production, wet phosphoric acid production, mild sour gas wells, urea production, and applications in the pulp and paper industry. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as forming, machining, and joining. Filing Code: SS-786. Producer or source: Allegheny Ludlum Corporation. Originally published May 2000, revised June 2002.

Applicability range for a high-strength duplex stainless steel in deep sour oil and gas wells

Laboratory tests in simulated sour downhole environments performed on a duplex stainless steel show correlation with the field experience for these alloys.