High Manganese Stainless Steel Research Articles

Effect of Heat Input on Weldability of Low Nickel High Manganese Stainless Steel.

Effect of Heat Input on Weldability of Low Nickel High Manganese Stainless Steel.

Mechanical properties and corrosion behaviour of developed high nitrogen high manganese stainless steels

AbstractInfluence of composition, specifically manganese and nitrogen content, on the microstructure associated corrosion resistance property of newly developed stainless steel has been studied. The developed steels have been characterised for their microstructure, mechanical and electrochemical properties. The results indicate that the addition of manganese and nitrogen as a substitute for nickel favours the austenite microstructure, higher yield strength (>350 MPa), tensile strength (>700 MPa), elongation and superior Charpy V‐notch impact toughness properties. The results obtained from electrochemical tests such as potentiodynamic polarisation and electrochemical impedance spectroscopy of manganese stainless steel show remarkable improvement (about 4 times) in corrosion resistance exhibiting passivity behaviour like that of commercial stainless steel (316L).

Performance analysis of hydrogen blowing in high manganese stainless steel smelting

Performance analysis of hydrogen blowing in high manganese stainless steel smelting

Influence of Groove on Metal Vapour Behavior and Arc Characteristics in TIG Welding of High Manganese Stainless Steels

Influence of Groove on Metal Vapour Behavior and Arc Characteristics in TIG Welding of High Manganese Stainless Steels

Influence of Sulfur Content on Penetration Depth in TIG Welding for High Manganese Stainless Steels

Influence of Sulfur Content on Penetration Depth in TIG Welding for High Manganese Stainless Steels

Metallurgical Nature of the As-Cast Microstructure of High-Nitrogen, High-Manganese Stainless Steels

Abstract High-nitrogen, high-manganese austenitic steels because of their non-magnetic behavior and corrosion resistance in combination with high strength and toughness serve various applications. The Schaeffler diagram is commonly used for predicting the as-cast microstructures but it does not reflect the nature of the austenite associated with the sequence of phase formation during solidification. Thermodynamic simulations are an aid to understanding the metallurgical nature of austenite. In this study, the microstructure was revealed by tint etching with examination using polarized light with the light optical microscope. The fragments of dendritic arms that share a common crystallographic orientation were identified by this technique. Two kinds of austenitic microstructures, both with grains formed by sharply defined primary and secondary dendritic arms and with grains having a blurred dendritic pattern, were observed. Solidification through austenite freezes the chemical inhomogeneity, whereas solidification through δ-ferrite, with subsequent transformation of δ-ferrite to austenite, leads to a “blurring” of the dendritic structure. These two kinds of microstructures were interpreted by a Schaeffler–Spiedel diagram which is modified in this paper. Electrochemical investigations showed that the chemical homogeneity of the austenite obtained by primary δ-ferrite solidification exhibited improved corrosion properties.

Non-Destructive Examination of Jacket Sections for ITER Central Solenoid Conductors

The Japan Atomic Energy Agency is responsible for procuring all amounts of central solenoid (CS) conductors for International Thermonuclear Experimental Reactor, including CS jacket sections. The conductor is cable-in-conduit conductor with a central spiral. A total of 576 Nb 3 Sn strands and 288 copper strands are cabled around the central spiral and then wrapped with stainless steel tape whose thickness is 0.08 mm. The maximum operating current is 40 kA at magnetic field of 13 T. CS jacket section is circular in square type tube made of JK2LB, which is high manganese stainless steel with boron added. Unit length of jacket sections is 7 m, and 6400 sections will be manufactured and inspected. Outer/inner dimension and weight are 51.3/35.3 mm and around 100 kg, respectively. Since the CS conductor suffers 60000 cycles of high electromagnetic force in the lifetime, severe requirements were specified for jacket sections in terms of not only high mechanical performance at 4 K but also of the size of initial defects in the jacket section. The minimum allowable defect size is estimated to be 2 mm2 × 0.2 mm by linear elastic fracture mechanics. Eddy current test (ECT) and phased array ultrasonic test (PAUT) were developed for non-destructive examination. The defects on inner and outer surfaces can be detected by ECT. The defects inside the jacket section can be detected by PAUT. These technologies and the inspected results of more than 700 jacket sections are reported in this paper.

Effect of Retained and Reversed Austenite on the Damping Capacity in High Manganese Stainless Steel

The effect of retained and reversed austenite on the damping capacity in high manganese stainless steel with two phases of martensite and austenite was studied. The two phase structure of martensite and retained austenite was obtained by deformation for various degrees of deformation, and a two phase structure of martensite and reverse austenite was obtained by reverse annealing treatment for various temperatures after 70 % cold rolling. With the increase in the degree of deformation, the retained austenite and damping capacity rapidly decreased, with an increase in the reverse annealing temperature, the reversed austenite and damping capacity rapidly increased. With the volume fraction of the retained and reverse austenite, the damping capacity increased rapidly. At same volume of retained and reversed austenite, the damping capacity of the reversed austenite was higher than the retained austenite. Thus, the damping capacity was affected greatly by the reversed austenite.

Establishment of Production Process of JK2LB Jacket Section for ITER CS

The Japan Atomic Energy Agency is responsible for the procurement of the central solenoid (CS) conductor for ITER. The CS conductor uses a circular-in-square type sheath tube (jacket, outer dimension: 49 mm × 49 mm square, inner diameter: 32.6 mm) made of high manganese stainless steel JK2LB. The CS jacket suffers high electromagnetic force with 60,000 cycles during its lifetime. Prior to mass-production of CS jacket sections for the ITER machine, production of 170 units of jacket sections has been carried out. During production, it was confirmed that dimensional and mechanical performances satisfy the ITER requirements. The nondestructive examination procedure for the CS jacket sections has been developed. As a result, mass-production processes of CS jacket have been established.

Status of Conductor Qualification for the ITER Central Solenoid

The ITER central solenoid (CS) must be capable of driving inductively 30 000 15 MA plasma pulses with a burn duration of 400 s. This implies that during the lifetime of the machine, the CS, comprised of six independently powered coil modules, will have to sustain severe and repeated electromagnetic cycles to high current and field conditions. The design of the CS calls for the use of cable-in-conduit conductors made up of and pure copper strands, assembled in a five-stage, rope-type cable around a central cooling spiral that is inserted into a circle-in-square jacket made up of a special grade of high manganese stainless steel. Since cable-in-conduit conductors are known to exhibit electromagnetic cycling degradation, prior to the launch of production, the conductor design and potential suppliers must be qualified through the successful testing of full-size conductor samples. These tests are carried out at the SULTAN test facility. In this paper, we report the results of the on-going CS conductor performance qualification and we present the options under consideration for the different modules constituting the CS coil.

Comparison Between Co2 — and Nd:Yag-Laser Beam Welding of High-Strength Crmnni Steels for the Automotive Industry

Austenitic and austenitic-ferritic CrMnNi-stainless steels are suitable materials in the transport and automotive industry due to their high corrosion resistance and high strength that allows weight and cost savings. This study focuses on the laser weldability of a commercial lean duplex and an austenitic high manganese stainless steel. The impact of different laser sources, i.e. a 5 kW CO2 — and a 4 kW Nd:YAG-laser, and of the main process parameters on the resulting weld quality will be investigated. One important aspect will concern the appearance of weld defects such as pores and hot cracks. The factors causing such internal imperfections will be analysed in order to find effective methods for preventing them. Weld microstructure and the associated corrosion and mechanical properties will be assessed with different techniques and adequate process parameters for high quality welds will be determined. The advantages and limitations of the applied welding processes will be evaluated for future applications.

Effects of nitrogen on the passivation of nickel-free high nitrogen and manganese stainless steels in acidic chloride solutions

The role of nitrogen on the passivation of nickel-free high nitrogen and manganese stainless steels was investigated in 0.5 M H 2SO 4, 3.5% NaCl and 0.5 M H 2SO 4 + 0.5 M NaCl solutions using potentiodynamic polarization, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy techniques. The passive film stability was enhanced in 0.5 M H 2SO 4 and the pitting resistance was improved in 3.5% NaCl solution by more nitrogen addition. The influence of nitrogen extended the whole anodic polarization region in 0.5 M H 2SO 4 + 0.5 M NaCl solution, as demonstrated by the enhanced dissolution resistance, promoted adsorption and passivation process, improved film protection and pitting resistance with increasing nitrogen content. Possible mechanisms relating to the role of nitrogen in different potential regions were discussed.

Wear Evaluation of High Interstitial Stainless Steels

A new series of high nitrogen-carbon manganese stainless steel alloys are studied for their wear resistance. High nitrogen and carbon concentrations were obtained by melting elemental iron-chromium-manganese (several with minor alloy additions of nickel, silicon, and molybdenum) in a nitrogen atmosphere and adding elemental graphite. The improvement in material properties (hardness and strength) with increasing nitrogen and carbon interstitial concentration was consistent with previously reported improvements in similar material properties alloyed with nitrogen only. Wear tests included: scratch, pin-on-disk, sand-rubber-wheel, impeller, and jet erosion. Additions of interstitial nitrogen and carbon as well as interstitial nitrogen and carbide precipitates were found to greatly improve material properties. In general, with increasing nitrogen and carbon concentrations, strength, hardness, and wear resistance increased.

Multicomponent phase selection theory applied to high nitrogen and high manganese stainless steels

Phase selection theory enables a prediction to be made as to which phase forms first when a molten alloy is solidified. Here it is applied to a multicomponent system to provide information about the δ–γ transition that may occur in high nitrogen and high manganese steels. The theoretical predictions are compared with experimental results for microstructures obtained by means of copper mould casting.

STABALLOY AG17

Abstract Staballoy AG17 is a very high manganese stainless steel developed for severe service in downhole drilling conditions. This datasheet provides information on composition, hardness, and tensile properties as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as machining. Filing Code: SS-857. Producer or source: Allvac Ltd.

Aging properties of vanadium-bearing high manganese stainless steel

Multiple precipitates have been utilized so as to improve the strength and strain hardening rate of austenite-based low density steel. Thus, a two-step heat treatment process including annealing and aging was designed for a V-containing Fe–20Mn–9Al-1.2C steel. Based on the analysis of microstructures and mechanical properties under different heat treatment processes, the precipitation behavior and strengthening mechanism were investigated. After annealing at 900 °C and aging at 550 °C, the microstructure of the steel consists of austenite matrix with V4C3 particles, κ-carbides and ferrite with DO3 particles. It is found that the steel exhibits an ultimate tensile strength (UTS) of 1339 MPa and specific strength (SS) of 199.3 MPa cm3/g. High strength and strain hardening ability result from the synthetic effect of shearing and Orowan mechanisms from multiple types of precipitates. Despite the low hardening ability, κ-carbides with shearing mechanism could enhance the yield strength significantly. Meanwhile, Orowan type V4C3 particles effectively improves the strain hardening rate as well as the strength. Fine planar slip bands with dispersive dislocation localization contribute to the strengthening of the steel.

低放射化耐熱性高マンガンステンレス鋼

The outline of recent study on heat resisting high manganese stainless steel is reviewed. High manganese stainless steel is now focused on a reduced radioactivation material used for first wall of fusion reactor. The substitution of manganese for nickel and that of tungsten for molybdenum are very effective to achieve a reduced level of longterm radioactivity. The concept of reduced activation materials is closely related to the waste management and reactor safety. The beneficial effects of alloying elements, carbon and nitrogen, on γ-phase stability and prevension of σ-phase formation in Fe-Cr-Mn alloy system are shown. High temperature tensile strength and creep properties of Fe-Cr-Mn alloy are also improved by alloying with carbon and nitrogen, and combined addition of tungsten and vanadium to the alloy is shown to be very helpful in increasing creep strength. Characteristic feature of void swelling by neutron irradiation is also discussed in these alloys.

Influence of tungsten, carbon and nitrogen on toughness and weldability of low activation austenitic high manganese stainless steels

The effect of alloying elements of tungsten, carbon and nitrogen on high temperature strength, toughness and weldability of Fe12Cr15Mn alloy has been investigated. The high temperature stregth of Fe12Cr15Mn0.2C0.1N at 873 K increases with the addition of 2–300W without affecting ductility. The toughness as estimated by Charpy tests, is also not influenced by the addition of 2–3%W, while the increase of carbon content decreases the absorbed energy. The transition temperature shifts to higher temperature by aging at 873 K for 3600 ks, but it is still lower than room temperature. The degradation of tougheness after aging is considered to be related to the precipitation of M23C6 on grain boundaries. The weldability evaluated by hot cracking susceptibility is not affected by alloying of tungsten and carbon in this alloy system. It is noted that the alloys studied show less hot cracking susceptibility than commercial AISI 316L stainless steel.

Extended ductility and cavitation in a high manganese stainless steel

The deformation behaviour of high manganese stainless steel has been studied by uniaxial test at temperatures ranging from 600° C (873 K) to 850° C (1123 K) and at strain rates of 2.8 × 10−4 to 1.4 × 10−2 sec−1. The maximum elongation (228%) is found to occur at 750° C (1023K) and with an initial strain rate of 4.16 × 10−4sec−1. Cavitation takes place throughout the gauge length of the specimens, with most of the cavities being located near to the fracture region. The cavitation phenomenon has been studied using metallography and the results have been analysed using a semi-empirical model of cavity growth. The cavity growth at high temperatures may be controlled either by diffusion or by a power-law growth process. For smaller cavity sizes, a diffusional growth mechanism is operative and there is a transition to a power-law growth process at a critical cavity radius, rc. The value of rc is found to increase with increase in temperature and decrease in strain rate. The computed critical cavity radii lie in the range of 0.7 to 2µm for the range of temperatures and strain rates used in this investigation.

Thermally induced segregation in high-manganese stainless steels

Thermally induced segregation in high-manganese stainless steels