Type 304L Research Articles

Considerations for the Weldability of Types 304L and 316L Stainless Steel

Considerations for the Weldability of Types 304L and 316L Stainless Steel

The mechanical properties of 316L/304L stainless steels, Alloy 718 and Mod 9Cr–1Mo after irradiation in a spallation environment

The Accelerator Production of Tritium (APT) project proposes to use a 1.0 GeV, 100 mA proton beam to produce neutrons via spallation reactions in a tungsten target. The neutrons are multiplied and moderated in a lead/aluminum/water blanket and then captured in 3 He to form tritium. The materials in the target and blanket region are exposed to protons and neutrons with energies into the GeV range. The effect of irradiation on the tensile and fracture toughness properties of candidate APT materials, 316L and 304L stainless steel (annealed), modified (Mod) 9Cr–1Mo steel, and Alloy 718 (precipitation hardened), was measured on tensile and fracture toughness specimens irradiated at the Los Alamos Neutron Science Center accelerator, which operates at an energy of 800 MeV and a current of 1 mA. The irradiation temperatures ranged from 50°C to 164°C, prototypic of those expected in the APT target/blanket. The maximum achieved proton fluence was 4.5×10 21 p/ cm 2 for the materials in the center of the beam. This maximum exposure translates to a dpa of 12 and the generation of 10 000 appm H and 1000 appm He for the Type 304L stainless steel tensile specimens. Specimens were tested at the irradiation temperature of 50–164°C. Less than 1 dpa of exposure reduced the uniform elongation of the Alloy 718 (precipitation hardened) and Mod 9Cr–1Mo to less than 2%. This same dose reduced the fracture toughness by 50%. Approximately 4 dpa of exposure was required to reduce the uniform elongation of the austenitic stainless steels (304L and 316L) to less than 2%. The yield stress of the austenitic steels increased to more than twice its non-irradiated value after less than 1 dpa. The fracture toughness reduced significantly by 4 dpa to ∼100 MPa m 1/2. These results are discussed and compared with results of similar materials irradiated in fission reactor environments.

Identification of processing parameters for Fe–15Cr–2.2Mo–15Ni–0.3Ti austenitic stainless steel using processing maps

The processing parameters for hot working of Fe–15Cr–2.2Mo–15Ni–0.3Ti austenitic stainless steel (alloy D9) are identified using processing maps developed on the basis of the dynamic materials model and hot compression data in the temperature range 850–1250°C and strain rate range 0.001–100 s-1. The efficiency of power dissipation increased with increase in temperature and decrease in strain rate. Dynamically recrystallised microstructures resulted when the efficiency of power dissipation was in the range 27–37%, i.e. in the temperature range 1050–1250°C and strain rate range 0.001–0.5 s-1. Flow localisation occurred in the regions of instability at temperatures lower than 1000°C and at higher strain rates. The dynamic recrystallisation regime observed in this alloy is compared with other austenitic stainless steels, namely, AISI type 304L and 316L.

Tritium and Decay Helium Effects on Cracking Thresholds and Velocities in Stainless Steel

Crack initiation and propagation were studied in three tritium-exposed stainless steels. The purpose was to measure cracking thresholds and velocities as a function of helium concentration in Type 21-6-9 stainless steel and compare the results to earlier measurements on Types 316L and 304L steels. Fracture toughness specimens were cut from forgings, fatigue-cracked and exposed to tritium at 423 K and 31 MPa. The samples were aged for selected times at 273 K to “build-in” 3He from tritium decay. Tritium concentrations ranged from 0-2600 atomic parts-per-million (appm) and 3He concentrations ranged from 0-600 appm. The samples were step-loaded at room temperature in air using a screw-driven mechanical testing machine and held at fixed displacement until crack initiation was detected. Crack propagation was monitored by continuously recording the drop in load until crack arrest. Threshold stress intensity was calculated from the load and the crack length at the end of the test. Crack velocities were determined from the load-time records and compliance relationships and verified on some samples using a DC potential-drop technique. The crack path was along grain and twin boundaries. For 21-6-9, the threshold for cracking decreased with increasing helium concentrations from about 90 MPa-m1/2 (50 appm helium) to 25 MPa-m1/2 (600 appm helium). Steady-state-crack velocities averaged 10-7 m/s and was not strongly dependent on helium concentration. The data show that embrittlement of tritium-exposed stainless steels is a form of hydrogen embrittlement made worse by the hardening of the microstructure from nanometer-sized helium bubbles that build-in with tritium decay.

Tensile behaviour of type 304 austenitic stainless steels in hydrogen atmosphere at low temperatures

The tensile behaviour of solution annealed type 304L, solution annealed type 304, and solution annealed and sensitised type 304 stainless steels was investigated in hydrogen and helium under a pressure of 1·1 MPa over the temperature range 300–80 K at strain rates ranging from 4·2×10-5 to 4·2×10-2 s-1. For 304L steel, hydrogen environment embrittlement (HEE) increased with decreasing strain rate. For 304L and 304 steels, HEE increased with decreasing temperature, reached a maximum, and then decreased with further decrease in temperature: the decrease was particularly rapid near the minimum temperature for HEE. Sensitisation enhanced the HEE of 304 steel. Above the maximum HEE temperature, the HEE behaviour was similar to the hydrogen embrittlement behaviour of materials in previous studies, but near the minimum temperature for HEE it was different. Three types of hydrogen induced brittle fracture were observed as a result of HEE: transgranular fracture along strain induced martensite laths and twin boundary fracture on the fracture surfaces of solution annealed 304L and 304 steels, and grain boundary fracture on the sensitised 304 steel. It was found that from room temperature to the maximum HEE temperature, the HEE of the materials depended on the transformation of strain induced martensite and below the maximum HEE temperature it depended on the diffusion of hydrogen.

微粉添加による304Lステンレス鋼焼結体の高密度化

Granulated type 304L austenitic stainless steel powders were made by adhering fine powders to conventional water-atomized powder of -100 mesh. Our study was carried out to investigate the effect of the fine powder addition on the densification behavior and gas-tightness of the sintered bodies made of these powders. These powders were compacted at 590 MPa, then vacuum-sintered at 1523 K for 3.6 ks. Gas-tightness test was performed by measuring the pressure reduction of compressed air(400 kPa) in the container.

Crack propagation tests of HIPed DSCu/SS joints for plasma facing components

Aluminum oxide dispersion strengthened copper (DSCu), used as the heat sink, and AISI 316L(N) type stainless steel (SS), used for cooling pipes, were metallurgically joined to be used as first wall of plasma facing components. Hot isostatic pressing (HIP) was proposed as the joining fabrication technique in the first-wall/blanket components. In this study, fracture toughness and fatigue crack growth rate tests were carried out for the fracture strength evaluation of HIPed joints. Permissible crack lengths during fabrication of first-wall components were evaluated from the results of the fracture toughness tests. In crack growth rate tests, the crack prepared in the DSCu propagated, turned at the HIPed interface, and propagated along it. Therefore, it was found that the crack provided in the DSCu heat sink did not propagate through the SS cooling pipe.

ALLEGHENY LUDLUM MINIMISER 304/304L

Abstract Allegheny Ludlum 304 and 304L are corrosion resistant type 18-8 stainless steels. Type 304L is the low carbon grade of Type 304 offering decreased carbide precipitation. The MINIMISER form is an improved machinability version, mostly by a change in the sulfur composition, but still maintaining the dual certification capability of the base Type 304/304L grades. This datasheet provides information on composition, physical properties, and elasticity. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-805. Producer or source: Allegheny Ludlum Corporation.

Impact resistance of 304L type stainless steel plates: Identification of Lemaitre and Chaboche damage model's parameters at different strain rates. Comparison with experimental results

The aim of the study is to validate the Lemaitre Chaboche damage model in the explicit finite element code EUROPLEXUS. Tensile tests have been performed on smooth and notched specimens of 304L type stainless steel to determine Lemaitre and Chaboche damage model's parameters at strain rates from quasi-static to 150 s -1 with different triaxiality ratios. The procedure of parameter's identification is based on finite element calculations. The damage parameters are identified through the experimental measurements. We present the results of an experimental investigation of the impact resistance of Inox 304L plates and compare these results with numerical simulations. The goal of the study is to determine the magnitude order of the perforation energy.

A model for creep-fatigue interaction in terms of crack-tip stress relaxation

A model was developed to explain the mechanism of the degradation of fatigue lives caused by the growth of transgranular crack without cavitational damage in spite of the creep-fatigue loading condition for some type 304L stainless steel and 1Cr-Mo-V steel. The model was developed by incorporating the stress relaxation effect during tensile hold time into the pure fatigue crack growth model based on the crack-tip shearing process. In the crack-tip region, the stress relaxation during hold time at the tensile peak stress reduces the maximum stress level but accumulates inelastic strain, which induces creep crack growth during hold time and enhances subsequent fatigue crack growth during subsequent loading by promoting the crack-tip shearing process. The predicted creep-fatigue lives by the model were in good agreement with the actual lives for type 304L stainless steel at 823 and 865 K and for 1Cr-Mo-V rotor steel at 823 K. The model was further expanded to explain the degradation of the life under the conditions of compressive hold cycling for 1Cr-Mo-V and 12Cr-Mo-V steels.

RAM 316L

Abstract RAM 316L is a machining-quality version of standard austenitic stainless steel type 316L. The alloy is designed to increase productivity and efficiency by allowing one to machine at higher speeds and feeds with less tool wear. 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, machining, and joining. Filing Code: SS-790. Producer or source: Rolled Alloys Inc.

Analysis of Different Methods to Calculate Electrochemical Noise Resistance Using a Three-Electrode Cell

Abstract In a theoretical approach, the noise resistance parameter (Rn (in time domain) was deduced from an electric equivalent model proposed by Bertocci and coworkers for a cell with three identical electrodes. The voltage and current were measured. The Rn and resistance of spectral noise (Rsn and Rsn0 [defined elsewhere]) were estimated for mild steel (MS) and stainless steel (SS) Type 304L (UNS S30403) electrodes immersed in four different solutions. The obtained results were converted into corrosion rate and finally compared with data measured with linear polarization resistance (LPR) and mass loss techniques. Electrochemical noise (EN) techniques had better agreement with other techniques in high corrosion rates. Furthermore, dispersed results were measured in low-activity systems.

Effect of Nitrogen Ion Implantation on the Corrosion Resistance of Titanium Modified Type 316L Stainless Steel in Comparison with Argon and Oxygen Ion Implantation

Studies on nitrogen ion implanted (1 x 10 15 , 1 x 10 16 , 1 x 10 17 and 2.5 x 10 17 ions/cm 2 ) titanium modified type 316L stainless steel (SS) showed an increase in the localized corrosion resistance of the material. Gracing Incidence X-ray Diffraction studies showed implanted nitrogen at the interstitial in the specimen implanted at 1 x 10 17 ions/cm 2 which showed the optimum corrosion resistance. Chromium nitride has been found in the dose of 2.5 x 10 17 ions/cm 2 , which showed the inferior corrosion resistance. Argon and oxygen ion implantations were carried out to confirm whether the improvement in the localized corrosion resistance after nitrogen ion implantation was due to chemical effect produced by nitrogen or due to microstructural effect produced by ion implantation. The results showed that nitrogen ion implantation improved more than two fold increase in the localized corrosion resistance with low passive current density. XPS studies of the passive film of implanted specimen (optimum dose) showed the presence of oxynitrides along with oxides which could have contributed to the enhanced corrosion resistance. The argon and oxygen ion implantations did not improve localized corrosion resistance and was found detrimental with increase in doses.

Stress Corrosion Test for Clad Plate Weldments with Compressive Stress Treatment Using the Anti-Welding-Heating Method

Abstract Stress corrosion of a type 304L stainless steel (SS [UNS S30403]) clad plate weldment was investigated prior to and after compressive stress treatment using the anti-welding-heating method...

Effect of Nitrogen Ion Implantation on the Localized Corrosion Behavior of Titanium Modified Type 316L Stainless Steel in Simulated Body Fluid

Nitrogen ion implantation on titanium-modified type 316L stainless steel (SS) at the energy of 70 keV was carried out at different doses ranging from 1×1015 to 2.5×1017 ions/cm2. These samples were subjected to open circuit potential (OCP)—time measurement, cyclic polarization, and accelerated leaching studies—in order to discover the optimum dose that can provide good localized corrosion resistance in a simulated body fluid condition. The results showed that the localized corrosion resistance improved with an increase in doses up to 1×1017 ions/cm2, beyond which it started to deteriorate. The results of the accelerated leaching studies showed that the leaching of the major alloying elements was arrested upon nitrogen ion implantation. Gracing incidence x-ray diffraction studies showed the formation of chromium nitrides at a dose of 2.5×1017 ions/cm2. X-ray photoelectron spectroscopy studies revealed the presence of these chromium nitrides in the passive film, which was attributed to the decreased corrosion resistance at a higher dose. Secondary ion mass spectroscopy studies on the passive film showed the variation in the depth profile upon nitrogen ion implantation. Thus, nitrogen ion implantation can be effectively used as a method to improve the corrosion resistance of the orthopedic implant devices made of titanium-modified type 316L SS. The nature of the passive film and its influence on corrosion resistance are discussed in this article.

Corrosion sous contrainte de mono et polycristaux d'aciers inoxydables austenitiques en milieu MgCl 2: Recherche d'ameliorations du comportement

The fractographic results of stress corrosion cracking of a 316L type austenitic stainless steel in MgCl 2 are in good agreement with the corrosion enhanced plasticity model. Based on the ideas of this model, the research of an improvement of the SCC resistance is attempted. It is shown that a cyclic prehardening can delay the initiation of the first microcracks and decrease the crack propagation velocity.

Influence des couches d'oxyde sur l'endommagement par fatigue d'un acier inoxydable de type 316l

bstract The fatigue damage behaviour of a 316L type stainless steet has been studied with special emphasis on the effects of oxide layers on surface damage processes. Samples pre-oxidized at 300 °C or at 600 °C in air and samples non pre-oxidized were prepared and tested in vacuum at different temperatures. The damage on both types of specimens was then compared. It appears that pre-oxidation can modify plasticity in the superficial grains and enhance intergranular microcrack initiation. These effects seem to be dependent on the oxide thickness and experimental conditions.

Etude fractographique de la fragilisation par l'hydrogene de lacier z2cnd 17-12 (aisi 316l)

Summary This paper concerns a fractographic examination of hydrogen embrittlement of a stable AISI 316L type austenitic stainless steel. The objective is a better understanding of the possible role of hydrogen in stress corrosion cracking processes.

Yag laser welding of neutron irradiated stainless steels

Type 304L stainless steel plates of 8 mm thickness irradiated in a boiling water reactor (BWR) to 1.2 × 10 25 n/m 2 ( E > 1.0 MeV) containing 9 appm helium from transmutation have been successfully welded using a high power Nd–YAG laser under conditions of both continuous wave (CW) and pulse modes. Unirradiated Type 316L stainless steel plate was lap welded to the irradiated Type 304L stainless steel plate under heat inputs ranging from 240 to 540 J/cm. Bead on plate welding was carried out under the same welding conditions as lap welding. Tensile tests of lap welded joints were conducted at room temperature. All joints fractured not in the irradiated materials but in the unirradiated materials and showed good mechanical properties. Based on these results it does not appear that helium affects the mechanical properties of joints. Small grain boundary cracks were observed in HAZ of the weld made by the CW YAG laser with heat inputs of 480 and 540 J/cm and crack length decreased with decreasing heat input.

Microstructure and corrosion resistance of a type 316l stainless steel

Characterization of the microstructure and chemistry of the oxide film of an air-oxidized type 316L stainless steel was carried out by an energy filtering transmission electron microscope equipped with an electron energy loss spectroscopy detector, and the corrosion resistance of the oxidized steel in a hot boiling sulfuric acid solution was evaluated by using an apparatus outlined by the International Standard Organization. It is demonstrated that the corrosion resistance of the steel in a 105°C, 30% sulfuric acid solution can be improved by an oxidation pretreatment of the steel in air at 500°C for 5 min, which produced an oxide film of ∼70 nm thick. The oxide film has a multilayered microstructure in which the topmost layer is composed of nanoscale γ-Fe 2O 3 grains of size ∼4 nm, followed by a mixture of α-Fe 2O 3 and Fe 3O 4 phases of grain size ranging from 20 to 75 nm. Chemical analysis of the oxide film across thickness direction using electron energy loss spectroscopy revealed that the O content in the oxide film decreases from the oxide surface toward the oxide\\steel interface. In addition, it is observed that an alloying depletion of Cr and Mn exists in the oxide film, compared with the alloying elements in the steel.