Percent Chromium Research Articles

Trace Elements and Accessory Minerals in Lunar Samples

Halogen contents similar to those in meteorites are reported in Apollo 11 samples. Concentrations of 0.6 to 13 parts mercury, 0.2 to 0.8 part uranium, 1 to 17 parts lithium, and 1 to 800 parts osmium per million and 0.5 to 1 percent chromium oxide by weight have been measured. In contrast to meteorites and terrestrial rocks a large mercury release below 110 degrees C is observed. Some implications of these results are presented. Fluorapatite, quartz, tridymite, fayalite, and iron-rich, manganese-poor pyroxmangite, previously unreported, have been identified. The small amount of fluorapatite found does not account for the fluorine contents.

Factors in Sulfide Corrosion Cracking of High Strength Steels

Abstract Results of laboratory sulfide corrosion cracking tests on commercial steel alloys are presented. Emphasis is placed on effects of environmental factors, alloy composition and metallurgical variables. Environmental factors studied include pH in the range of 2 to 5, H2S partial pressures in the range 0.001 to 1.0 atmosphere and addition of sodium chloride. Twelve percent chromium stainless steels and low alloy steels containing more than 1 percent nickel, were found to have lower resistance to cracking at the same hardness level than low alloy steels normally used for oil field equipment. Plastic deformation of low alloy steels by cold rolling decreased the resistance to cracking.

Study on 12 percent Chromium Heat Resistant Steel (2nd report)

Study on 12 percent Chromium Heat Resistant Steel (2nd report)

Anodic Behavior of Titanium and Commercial Alloys in Sulfuric Acid

Abstract The anodic polarization behavior of commercially pure alpha titanium 75A (annealed), beta alloy 13V-llCr-3Al (annealed) and alpha-beta alloy 6Al-6V-2Sn (heat treated to strength levels of 140, 160 and 180 ksi) in hydrogen saturated 5, 12 and 20 percent sulfuric acid solutions was investigated at 20, 35, 50 and 65 ± 1 C, using a potentiostatic technique. All specimens exhibited active to passive transition at temperatures above 20 C and acid concentrations greater than 5 percent Titanium alloy 13V-11Cr-3Al showed transpassive behavior which was attributed to the 11 percent chromium content Increasing acid concentration increased me critical current for passivity and shifted the critical potential for passivity in the noble direction. Increasing the temperature served only to increase the critical current for passivity. Temperature coefficients and activation energies were the right order of magnitude for a reaction controlled by reactivity at the metal surface. For the alpha beta alloy 6Al–6V–2Sn the critical current for passivity increased as the ratio of amount of alpha to beta phase increased with increasing strength level. The dissolution is accelerated, probably, by the galvanic effects and the unfavorable area ratio. Ti 75A, a commercially pure metal and Ti 13V-11Cr-3Al, a homogeneous single phase alloy, had a smaller critical current for passivity values man did Ti 6Al-6V-2Sn, a multiphase alloy, which was expected. The effect of Fe3+, Cu2+ and Cl− on polarization of Ti 6Al-6V-2Sn (180 ksi) was investigated also. Fe3+ and Cu3+ inhibited the anodic dissolution reaction and Cl− facilitated passivation.

Fe-Cr-N合金の内部摩擦および窒化クロムの析出

Nitrogen diffusion peaks in iron chromium alloys containing less than 1.5 atomic pct chromium were measured at the frequencies of 1.0 and 102 c/s. Two abnormal peaks were observed on both temperature sides of the usual nitrogen peak in unalloyed iron. From peak shifts, activation energies for the low and the high temperature peak were calculated as 16 kcal/mol and 20 kcal/mol, respectively. The high temperature peak is put down as being due to nitrogen atoms in the vicinity of chromium atoms, while the mechanism of the low temperature peak is interpreted as jumps of nitrogen atoms in strained Fe-Fe interstices which are produced by the addition of chromium atoms. Although it is not obvious whether the high temperature peak is describable in terms of a single relaxation time or not, it is reasonable for the low temperature peak to introduce a distribution of relaxation times. Precipitation of nitride phases, Fe8N, Fe4N and CrN, from Fe-Cr-N alloys were investigated by measuring electrical resistivity. Internal friction peaks were also measured after the precipitation of the chromium nitride as a function of chromium contents. Precipitation of the chromium nitride was clearly observed even in 0.2 atomic pct chromium alloy. Consequently, soluble nitrogen atoms in alpha iron-chromium alloys are decreased due to the precipitation of the chromium nitride.

The Oxidation off Iron, Nickel and Cobalt-Base Alloys Containing Aluminum

Abstract By conducting continuous weight-gain measurements from 500 to 1300 C on a variety of Fe-Al, Fe-Cr-Al, Ni-Al and Co-Al alloys in oxygen at 100 torr and examining the reaction products which form, reasons for the enexpected ineffectiveness of preferential aluminum oxidation have been explored. With Fe-4.4 percent Al and Fe-12 percent Al, there are two different regions of parabolic growth- these are associated with the appearance of γ-A12O3 below 900 C and α-Al2O3 above. The latter is normally more protective but possesses a greater tendency for cracking and spalling; adding 24.6 percent chromium promotes its formation at lower temperatures. With Ni-5.0 percent Al, two displaced regions are also found; here, nickel penetrates alumina to provide intermediate NiO · Al2O3 and an outer layer of NiO. With Co-4 percent Al, somewhat less cobalt penetrates γ-Al2O3 to provide CoQ · Al2O3 and an outer layer of Co3O4. When both CoO and α-Al2O3 are stable phases, the latter grows mainly by internal oxidation and offers little protection.

Paper 3: Wire-Wool Type Failures in 3 Percent Chromium—½ Percent Molybdenum Steel Journals—A Preliminary Evaluation of Some Palliatives

Paper 3: Wire-Wool Type Failures in 3 Percent Chromium—½ Percent Molybdenum Steel Journals—A Preliminary Evaluation of Some Palliatives

High Temperature Mercaptan Corrosion of Steels

Mercaptan sulfur content is a more reliable indicator of a petroleum naphtha's corrosivity at elevated temperatures than is total sulfur content.Corrosion of steels by mercaptan vapors at 650–850 F was found to be essentially linear with time and the double-sulfide scale typical of H2S corrosion was formed. The corrosion rates were proportional to the mercaptan concentration and gave Arrhenius activation energies of 11–16 k cal/mole. Hydrogen accelerated mercaptan corrosion and voided the corrosion resistance obtained by adding up to 9 percent chromium to the steels. Corrosion rates were the same in primary, secondary and tertiary amyl mercaptans.At 750 F, the amyl mercaptans were thermally stable in the test apparatus. About 10 percent of the n-amyl mercaptan decomposed thermally to H^S at 850 F. However, at 750 F, some corroding metals and some corrosion scales caused the mercaptans to decompose. The effect of exposure time on the decomposition can be correlated with surface changes caused by corrosion reactions. The stability of the mercaptans in the presence of corroding steels was primary>secondary>tertiary.Corrosion and mercaptan decomposition both were reduced by the presence of halides. Added H2S in the corroding gases reduced mercaptan decomposition without affecting the corrosion rate.An assumed free-radical mechanism can be used to explain qualitatively both the corrosion reactions and the mercaptan decomposition.

A Study on Tempering Thirteen Percent Chromium Stainless Steel. (On the Change of the Internal Friction at Room Temperature after Tempering)

A Study on Tempering Thirteen Percent Chromium Stainless Steel. (On the Change of the Internal Friction at Room Temperature after Tempering)

Oxidation of Iron-Chromium Alloys at 750–1025C

Abstract The rates of oxidation of iron alloys containing 0.2 to 10 percent chromium were measured at 750 to 1025 C. The nature of the corrosion products was investigated by metallography, x-ray di...

High Temperature Sulfur Corrosion Of Intermediate Range Chromium Steels

Abstract Laboratory tests were made to find a suitable replacement material for 5 percent chromium— 1/2 percent molybdenum tubes used in a thermal desulfurization unit. The steel found most suitable for this use had a 9 percent chromium content. Maximum corrosion loss in wall thickness of this material was less than 0.030-inch, with a total expected life of at least five years. The sulfur content of various crudes commonly used in furnaces is reported. 8.4.3, 6.2.4

The Shift of the Magnetic Transformation Temperature Caused by Annealing at 600°C and above in Iron-Chromium Alloys containing 40 to 60 Percent Chromium

The Shift of the Magnetic Transformation Temperature Caused by Annealing at 600°C and above in Iron-Chromium Alloys containing 40 to 60 Percent Chromium

Neutron Diffraction Studies of Chromium-ModifiedMn2Sb

Existence of a ferrimagnetic to antiferromagnetic phase transition with decreasing temperature in Mn2Sb modified with 2.3 weight percent chromium is confirmed by neutron diffraction.Received 5 July 1960DOI:https://doi.org/10.1103/PhysRev.120.1969©1960 American Physical Society

Electrical Resistance Measuring Device Plus Statistical Analysis Yield Unique Approach to Corrosion Problems

Abstract A new technique for analyzing electrical resistance measuring device data is described. A 5 percent chromium, 1/2 percent molybdenum corrosion probe was used to measure corrosion rates in ...

熔融鉄-クロム系のクロムの活量

The activities of chromium in the liquid systems of iron-chromium and iron-chromium saturated with carbon were determined by a vaporization method using radioactive Cr51. The experiments were carried out at 1630°C up to about 40 at. pct chromium. It was found that iron-chromium system is a regular solution, showing negative deviation from the Raoult’s law. The interchange energy w was found to be about −10 kcal/mole. The value of w calculated from the phase diagram is also negative, but is not in good agreement with the above. It is theoretically inferred that the deviation from the Raoult’s law is larger in iron-chromium system than in iron-nickel system. The addition of carbon lowers the activities of chromium and the interaction parameter εCrC in carbon-saturated system is −12∼−16 over the composition range 0∼10 at. pct chromium.

Iso-Corrosion Rate Curves—For High Temperature Hydrogen-Hydrogen Sulfide—A Contribution to the Work of NACE Technical Group Committee T-8

Abstract Iso-corrosion rate curves were drawn for the 0–5 percent chromium steels and for chromium-nickel austenitic steels in high temperature hydrogen-hydrogen sulfide. These curves show the maximum corrosion rates expected over wide ranges of hydrogen sulfide concentrations and temperatures such as would be encountered in petroleum catalytic refining processes utilizing hydrogen. The pressure variable was confined to the range 175–500 pounds per square inch gauge. 3.4.8

Hall Effect and Resistance of Dilute Gold-Chromium Alloys at Low Temperatures

The temperature dependence of the Hall effect and of the electrical resistance has been investigated in pure gold and in gold containing 0.03 and 0.05 atomic percent chromium, principally at temperatures in the liquid helium region. For these compositions the temperature dependence of the resistance is abnormal at low temperatures, exhibiting a resistance minimum. No corresponding anomaly was observed in the Hall effect, but neither was it constant as one might expect in terms of a simple theory. Instead, a monotonic increase of the Hall constant with decrease in temperature was obtained below room temperature. This behavior is not influenced by the presence of a resistivity minimum to any appreciable extent. The experimental results favor the interpretation of the resistance minimum as a scattering phenomenon. The specimens were in the form of annealed foils, approximately 20\ifmmode\times\else\texttimes\fi{}10\ifmmode\times\else\texttimes\fi{}0.04 mm. A special circuit permitted measurement of the Hall voltages to 0.01 \ensuremath{\mu}v, or about 1 part in 1000.

High Temperature Hydrogen Sulfide Corrosion★

Abstract High temperature hydrogen sulfide corrosion of carbon steel and low chrome alloys has become a serious problem in the petroleum industry in connection with the increasing use of high pressure hydrogenation and dehydrogenation processes for upgrading petroleum fractions. The effect of temperature, pressure and hydrogen sulfide concentration on the corrosion rate of a wide range of commonly used carbon steels and alloys has been determined in laboratory tests. It has been established that the low chrome alloys (up to 5 percent chromium) which have been used to combat sulfur corrosion in fractionation and cracking equipment, show little or no advanage over carbon steel in resisting attack by hydrogen sulfide. Of the conventional alloy steels tested, only the 18-8 chrome nickel and higher alloys have shown good resistance to this type of corrosion over a wide range of pressure, temperature and hydrogen sulfide concentration. It was found that aluminum coated steels also showed very good corrosion resistance. Three methods were proposed for minimizing hydrogen sulfide corrosion: (1) Reduction of hydrogen sulfide in process streams, (2) Use of chrome-nickel alloys, and (3) Protection of metals by aluminum coating.

酸性河水発電所における腐蝕および防蝕の研究（第16報）高Cr鋼の耐蝕性に及ぼす熱処理の影響並びに熔接部の腐蝕について

The corrosion resistivity of thirteen percent chromium steels in week acid river water is conciderably good, but it differs by heat-treatment, so we have studied on the effect of heat-treatment on corrosion rate of these steels. When they are tempered at several temperature after rapid cooling from γ phase, the corrosion rate increases very much by tempering between 500∼600°, especially at 550°. This is due to the decrease of chromium concentration by the precipitation of chromium carbides. But when they are tempered at more than 700°, the corrosion rate decreases again, we think that this is due to the fact that the concentration of chromium in the matrix becomes uniform by the tempering at high temperature. The welded parts in these steels are deeply corroded, but when they are tempered above 700° after welding, the corrosion in the welded parts can be prevented. The welded parts on 13% Cr-steel added with 1% titamium are not corroded even in fresh-welded state.

Stress Corrosion Cracking Of Hardenable Stainless Steels

Abstract Hardenable stainless steels, like other high-strength steels, are susceptible to cracking under the combined influence of tensile stress and corrosion, depending on the severity of the stress, the nature of the media and to a large extent, on their hardness. The most severe conditions are acid solutions containing sulfides, which promote entry of hydrogen into the steel and where chlorides are present to promote pitting. In such media cracking may occur in the standard grades under stress at hardnesses of Rockwell C24, in severe marine atmospheres at C40 and in industrial atmospheres at C45. Type 422, a modified 12 percent chromium alloy, tempered at 1200 F to Rockwell C30 and the precipitation-hardening alloys, 17-4 PH and 17-7 PH, overaged to the same hardness level were the most resistant materials tested. Types 410, 416 and 431 performed as well as or somewhat better than low alloy steels when heat treated to equivalent hardness levels. Tempering them at 1100 F or higher temperatures provided good resistance to cracking in the severest media. Internal stresses generated during quenching can promote stress corrosion cracking without imposing additional external stresses. Interrupted quenching (martempering) is helpful in minimizing stresses from this source and is recommended as a heat treating practice for valve trim and other parts used fully hardened in service likely to cause corrosion cracking.