Series Stainless Steels Research Articles

Comparison of residual microstructures in stainless steel after very high pressure shock deformation

It is now well documented that the explosive shock hardening of 304 and other 300-series stainless steels (which has been reported over a period of nearly two decades) is due in large part to the formation of deformation twins or twin faults. It has been shown in fact that for plane-wave shock loading where the sample is subjected to a pure, compressional shock wave, the hardening saturates with pressure and declines at pressures near or above 1 megabar (>100 GPa) due to thermal effects.In experiments involving plane-wave shock loading and which employed a flyerplate technique, each test at a specific pressure or pulse duration involved a separate explosive event and required difficult and elaborate experimental arrangements. In some respects this was a convenient arrangement because thin sheets could be sandwiched in these assemblies, providing a convenient regime for transmission electron microscopy of the shock-induced microstructures.

CRUCIBLE XM 19 STAINLESS

Abstract CRUCIBLE XM 19 Stainless is a nitrogen-strengthened, low-carbon austenitic stainless steel that provides good corrosion resistance in combination with high strength. The alloy has better corrosion resistance than AISI Type 316 with approximately twice the yield strength. It can be welded, machined and cold worked using the same equipment and methods used for the conventional AISI 300 series stainless steels. It is nonmagnetic as annealed and after severe cold work. Its many uses include cables, fasteners, pumps, valves, marine hardware and springs. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness. It also includes information on low temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: SS-414. Producer or source: Crucible Specialty Metals Division, Colt Industries.

UNILOY 430

Abstract UNILOY 430 is a medium-chromium (17%) non-hardening, ferritic stainless steel. Of the AISI 400 series stainless steels, Uniloy 430 most nearly resembles the 18% chromium-8% nickel stainless steels in fabrication and service. It has excellent resistance to corrosion and good resistance to elevated-temperature scaling. Its many uses include architectural trim, nitric acid storage tanks and kitchen appliances. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-408. Producer or source: Cyclops.

Surface modification of 300 series stainless steel by a deuterium plasma

Samples of 300 series stainless steel (SS) and Mo have been exposed to 300 eV and 20 eV D + 3 ions from a deuterium plasma with fluxes up to 1.7 × 10 17 D · cm −2s −1. The exposed surfaces were examined by scanning and transmission electron microscopy. Although the highest fluxes produced evidence of erosion, no blisters were seen. The same exposure given to Mo, however, produced extensive blistering. The experimental results are compared with theoretical computations of hydrogen transport in SS and interpreted in the context of a model for hydrogen blistering.

Observations of Gas Bubbles in an Austenitic Stainless Steel Charged with3H

Nitronic 40 is a high-strength austenitic stainless steel. Investigations are in progress to explore the possibility of using this material as a high-strength substitute for 300 series stainless steels, especially in hydrogen environments. There is also interest in determining the influence of helium on the mechanical properties of this material from the viewpoint of fusion reactor systems. The alloy is nominally (in weight percent) 21 Cr, 6 Ni, 9 Mn, and 63 Fe and is strengthened by 0.35 wt % N. Smooth bar tensile specimens approximately 3.5 mm in diameter with 25 mm gage lengths were machined from high energy rate forged (HERF) stock. These specimens were then gas phase charged with 2H at 64 MPa pressure at 470 K or 3H at 47.5 MPa at 345 K for 1450 h. Due to the nature of the charging the 3H distribution was nonuniform, ranging from approximately 1300 ppm at the specimen surface to less than 5 ppm at a depth of 0.5 mm from the surface. Following charging, the specimens were stored at ˜250 K for 5.5 years. Approximately one-third of the tritium decayed to 3He during this period, yielding a maximum of 900 ppm of 3He at the surface of the specimens. Tensile tests at 298 K revealed a significantly greater loss in ductility in the specimens charged with 3H. Following tensile testing TEM specimens of suitable size were sectioned near the fracture surface, thinned using conventional techniques for radioactive specimens, and examined. Electron microscopy was performed in a Philips EM 400T equipped with a field emission gun.

The Role of Sulfide Inclusion Morphology in Pit Initiation of Several Type 300 Series Stainless Steels

Abstract Pitting potential measurements have been made on several single phase Type 300 series stainless steels and duplex Type 304L alloy by the potentiodynamic test method. The heat of Type 316L stainless steel examined was more susceptible to pit initiation than the heat of Type 304L stainless steel that was studied. Several heat treatments were examined, and the effects of chloride ion concentration, pH, and temperature of the electrolyte on the pit initiation of single phase and duplex alloys were investigated. The effects of heat treatment demonstrate the importance of the morphology of sulfide inclusions that are exposed to the electrolyte. The sulfide dissolution kinetics, which are presumed to control the pit initiation process, are influenced by the morphology of the inclusions exposed to the electrolyte, the time constraints of the various pitting corrosion test methods, the temperature and composition of the bulk electrolyte, and the spectrum of sulfide inclusion compositions present in the alloy.

Materials of construction in the fatty acid industry

AbstractThe basic material of construction for the tankage and reactors that are used in the fatty chemical industry is one or another variant of the 300 series stainless steels. The use of these alloys essentially eliminates the possibility of iron and other metal contaminations which may either degrade the product or catalyze undesirable oxidation and other side reactions. With certain exceptions, it has been found that Type 304 stainless steel may be used in fatty chemical processing at temperatures up to 150 C and Type 316 stainless steel for tanks and vessels designed for use above that temperature. Where welding is involved in the fabrication of equipment designed for high temperature usage, it has been found necessary to use either a special low carbon stainless steel or an alloy which contains an extra ingredient that will inhibit carbide precipitation in the weld area since such precipitation usually results in a point of corrosion and ultimate failure. in the fabrication of pressure vessels, it is normal practice to use carbon steel plates of suitable thickness that have a minimal amount of the desired alloy bonded to the surface rather than fabricate of solid alloy. This not only reduces the cost of the vessel but adds greatly to the strength of the sheet since most high alloys lose tensile strength rapidly as temperatures are increased while carbon steel retains strength until very high temperatures are reached. In addition to the 300 series stainless steels, certain highly specialized alloys such as Inconel 825, Carpenter 20 Cb, or Monel are frequently used for extreme acid conditions. The lower cost of aluminum as compared to a high alloy makes it attractive for storage tanks but it can be used only when materials contain no moisture, since even traces of water accelerate the rate of corrosion and rapidly render the tank unusable. New materials on the scene are fiberglass‐polyester tankage and applied linings of the phenolic or the epon‐epoxy type. These materials do not have a wide application, but where their use is possible, it is a lower cost answer to the problem of iron contamination.

Quantitative Analysis of 300 and 400 Series Stainless Steel by Energy Dispersive X-Ray Fluorescence

Recent developments in analytical techniques and software have allowed the accurate quantitative determinations of both the major and minor elements in stainless steels by energy dispersive x-ray fluorescence. The successful analysis of 300 and 400 series stainless steel is reported utilizing this technique. The analysis of this type of material represents one of the most severe tests of the method due to numerous peak overlaps and interelement effects such as absorption and enhancement.Sixteen standards of ASTM 300 series and ten 400 series were prepared by polishing on a 220 grit aluminum oxide belt and subsequently washing the surface in absolute methanol. Analyses were performed with an EG&G ORTEC 6110 Tube Excited Fluorescence Analyzer utilizing a dual anode (Rh/W) x-ray tube. Peak deconvolutions and interelement corrections were made with a 16K PDP-11/05 computer utilizing the program FLINT (1). Utilization of spectral deconvolutions and interelement corrections yields a relative accuracy of approximately IX of the concentrations of the major elements.

Stress Corrosion Behavior of Fe-Cr-Ni and Other Alloys in High Temperature Caustic Solutions

Abstract The resistance of various commercial alloys to stress corrosion cracking (SCC) in 50% NaOH has been evaluated at temperatures in the range 284 to 332 C. Austenitic alloys tested included Type 300 series stainless steels, Monel Alloy 400, Inconel Alloys 600, 625, 690, Incoloy Alloys 800, 804, 825, Hastelloy Alloy C, and Nickel 201. Other materials tested were Croloy 2¼Cr-1Mo steel, ferritic stainless steels Type 446, 26-1S, and EB 26-1, and commercial purity titanium. The effects of alloy composition, heat treatment, and test temperature on the severity of SCC were examined. Increasing the nickel content increased the resistance of SCC in deaerated 50% NaOH. In an aerated 50% NaOH solution, both high chromium and high nickel contents were necessary to increase stress corrosion resistance. In deaerated 50% NaOH, ferritic alloys exhibited high corrosion rates and displayed structure sensitive cracking behavior. Titanium corroded rapidly but did not crack. The greatest overall resistance to SCC in de...

The low temperature magnetic properties of austenitic Fe-Cr-Ni alloys: 2. The prediction of Néel temperatures and maximum susceptibilities

The compositional dependence of the Néel temperature has been studied, from data derived by different techniques and by various authors, for 30 austenitic stainless steels or special Fe-Cr-Ni alloys whose compositions fall near the range of the AISI 300 series. A linear relationship enables the predicted Néel temperature, T N to be evaluated with an rms deviation of 3.5 K on the basis of the wt % of alloy constituents. The effect of alloying elements in lowering T N ∗ increases in the order Cr, Ni, Mo, and Si, while Mn is unique in raising T N ∗ . By comparing this equation for T N ∗ with previous equations to predict the onset of a martensitic phase change at a temperature M s , it is concluded that isotherms for M s in ternary Fe-Cr-Ni alloys should also be parallel to the tangent to the boundary between fcc and bcc phases calculated from thermodynamic data. This conclusion throws doubt on the applicability of the Eichelman and Hull equation to the 300 series of stainless steels. If γ phase stability is achieved by adding Cr, Ni, Mo, or Si, the alloys are likely to be ferromagnetic at low temperatures, but if structural stability is due to C, N, or Mn, then the alloys should be antiferromagnetic or superparamagnetic. A logarithm plot of the maximum initial susceptibility versus Ni content can be used to estimate X v max in the AISI 300 series stainless steels. This relationship does not apply to alloys with Mn > 2 wt %, but in these the value of X v max is lowered. The significance of these observations is discussed in terms of the application of stainless steel in magnetic environments at low temperatures.

Decorative coating of plastics by vapor deposition of various alloys

AbstractStringent government environmental regulations applied to the electroplating industry have spurred a search for alternative means of providing chromium coatings on plastics. Vapor deposition, an established and extensively utilized process for applying aluminum coatings on plastics, is quite naturally being investigated as an alternative process. Vapor deposited chrome has a darker cast than electrochrome, and a great‐number of materials are being investigated to find a color matching substitute that will stand up under severe environmental conditions. Among these are the 300 and 400 series stainless steels, nichrome, and other alloys. It has been found, with proper surface preparation, that highly adherent and specular stainless steel coatings/can be obtained oh plastics using filament and boat evaporation techniques. The coatings resemble a highly polished version of the parent metal and bear a striking resemblance to chrome. However, some type of clear topcoat is required to provide abrasion resistance.

The re-solution of inclusions in remelted stainless steels

As a follow-up to work done on the remelting of three grades of 300 series stainless steels on a small scale electroslag remelting unit, adjunct studies were made on the kinetics of inclusion re-solution during the “electrode stage” of remelting. The objective of this study was to attempt to quantify the metallographic observations of many investigators that vary-ing degrees of inclusion re-solution do take place during the consumable remelting of numer-ous grades of metals and alloys. In specific, the rate(s)of re-solution of the large stringer inclusions found in the 300 series air melt stock was investigated. A known and controlled temperature gradient was imposed on long cylindrical specimens for varying times and, by a metallographic inclusion sizing and counting technique described in this paper, a series of isochronal and isothermal data was generated. Plots of rates of re-solutionvs time indi-cated a zero-order reaction mechanism and the activation energy calculated from the mea-sured reaction rate constants was found to be 36,000 J/mole.

Phase transformation of stainless steel during fatigue

Transformation of austenite during cyclic loading was studied in AISI 301 and 304 alloys whose stability was adjusted by heat treatment and temperature changes. Fatigue life was determined under controlled strain amplitude tension-compression conditions. The amount of transformation to α’ (bcc) martensite was continuously indicated magnetically during testing, and the α’ and ∈ (hcp) phases were observed metallographically at failure. It was found in room temperature testing that at strain amplitudes in excess of 0.4 pct the formation of α’ (bcc) martensite was detrimental to the fatigue life. At 200°F (366 K) the fatigue life of an unstable alloy was increased, while in a completely stable austenitic alloy (20Cr, 6Ni, 9Mn), the life at 200°F (366 K) was less than that at room temperature for the same cyclic strain amplitude. The differing effect of temperature on life of these two types of alloy is attributed to the alteration of the austenite stacking fault energy and the relative free energies of the α’ (bcc), ∈ (hcp) and γ (fcc) phases in the unstable alloys. It has been observed that within the standard composition ranges of the two 300 series stainless steel grades there can be marked differences in the degree of transformation resulting from cyclic loading. This has the implication that for fatigue applications modifications in the specifications for the different grades of stainless would be advantageous.

Mechanical properties of high purity Fe-26 Cr-1 Mo ferritic stainless steel

The physical metallurgical characteristics of high purity Fe-26 Cr and Fe-26 Cr-1 Mo ferritic stainless steels, containing low carbon and nitrogen contents, were studied. The studies demonstrate that a commercially produced Fe-26 Cr-1 Mo high purity alloy containing a maximum of 50 to 150 ppm of carbon and nitrogen is capable of good mechanical properties and fabricability. The alloy was previously demonstrated to exhibit good corrosion resistance. Because of these properties, the high purity Fe-26 Cr-1 Mo alloy is a viable alternate to 300-series stainless steels as well as more highly alloyed materials for many applications.

Stainless Steel for Fine Wire

After investigating the influence of various factors upon the burst in drawing under the drawing method of stainless steel production for fine wire it was confirmed that the causes giving the biggest influence lie the warm softening resistance and non-metalic inclusion and further it was found that 18 Cr-18 Ni-2.5 Mo-3.5 Cu steel was proper as austenite series stainless steel for fine wire from the result and also from the point of view of decreasing the dice wear.

Behavior of Austenitic Stainless Steels in Evaluation Tests for the Detection of Susceptibility to Intergranular Corrosion

Abstract The characteristics, advantages, and limitations of various methods for the detection of susceptibility to intergranular corrosion in austenitic stainless steels due to carbide precipitation are discussed. Information on corrosion rates and acceptance limits in nitric acid and ferric sulfate-sulfuric acid tests is presented and illustrated by statistical data from the evauation of approximately 10,000 samples representing commercial AISI 300 series stainless steels.

Investigation of Stress Corrosion Cracking Susceptibility of Fe-Ni-Cr Alloys in Nuclear Reactor Water Environments

Abstract Nonstabilized 300 series stainless steels stressed over yield are susceptible to intergranular stress corrosion cracking (SCC) when exposed in the heavily sensitized condition to 288 C (550 F), high purity water containing dissolved oxygen. The effects of stress, oxygen levels, and significant metallurgical parameters on intergranular SCC of AISI Type 304 are being evaluated. Several promising intergranular SCC resistant alternate alloys have been identified through preliminary investigations, e.g., austeno-ferritic duplex and stabilized austenitic stainless steels.

The Thermal Conductivities of Some 400 Series Stainless Steels

The Thermal Conductivities of Some 400 Series Stainless Steels

The Relationship of Heat Treatment to the Corrosion Resistance of Stainless Alloys

Abstract Information is presented on the response to sensitizing heat treatments of Incoloy 800, Incoloy 825, Carpenter 20 Cb-3, Inconel 600, Inconel 625, and Hastelloy G. None of the alloys investigated was found to be consistently immune to the development of susceptibility to intergranular corrosion as measured by nitric acid and ferric sulfate-sulfuric acid evaluation tests. In most cases the two test methods were in substantial agreement but the ferric sulfate-sulfuric acid test was less sensitive to thermal effects for Incoloy 825 and more sensitive for Hastelloy G. In general, variability in resistance to sensitization as a function of prior processing history appears to be more pronounced in the higher nickel alloys than in the 300 series stainless steels.

The Changes of Structure and Mechanical Properties of 18-8 Series Stainless Steels after Prolonged Aging

The Changes of Structure and Mechanical Properties of 18-8 Series Stainless Steels after Prolonged Aging