Low Chromium Steels Research Articles

クロム鋼の光輝加熱について

When the chromium steel is heated in the atmosphere, containing the appreciable amount of oxidizing gas such as moisture and carbon dioxide, it is oxidized and discolored due to the low dissociation pressure of the chromium oxides. We studied, in this experiments, the effects of gas constituents in the atmosphere and heating temperature, the chromium content in steel to the surface brightness and the nitriding effect of steel.As the results of this experiments, low chromium steel is heated without surface discoloration and decarburization in the atmosphere of hydrogen, hydrogen and nitrogen or (hydrogen, nitrogen and carbon monoxide) gas which have low moiature content.The heat-treatment of high chromium steel becomes comparatively easy as the heating temperature get higher. The nitrogen content of the steel tends to increase as the partial pressure of nitrogen increases, and decrease as the chromium content of the specimen increases.

Effect of Hot Hydrogen Sulfide Environments on Various Metals★,—A Contribution to the Work of NACE Task Group T-5B-2 on Sulfide Corrosion at High Temperatures and Pressures in the Petroleum Industry from Sinclair Research Laboratories, Inc., Harvey, III.*

Abstract Sinclair platinum catalyst reformers and desulfurizers designed on corrosion rate data taken from literature and laboratory tests had low corrosion rates. However, scaling as a result of high temperature sulfide attack caused clogging and pressure drop. Plant and bench scale corrosion tests were made using specimens of various steels and alloys directly in catalyst beds. These tests showed that at hydrogen sulfide concentrations considered low only 18-8 stainless steel exhibited sufficient resistance for long time service. Test apparatus is described, procedure outlined and corrosion rates reported on tests made. Examples of scale formation are shown, constituents analyzed and explanation of scale phenomena offered. Tests resulted in decisions concerning additional equipment and pointed to certain alloys as desirable for service expected. Refinery corrosion tests of alloy steels and aluminum coated carbon steels were made and corrosion rates plotted, indicating that low chromium steels are satisfactory provided the hydrogen sulfide-hydrogen ratio is lower than 100 ppm. Aluminum coated steels proved to have marked resistance to attack with best results achieved with calorized coatings. Conclusions on proper material selection related to hydrogen sulfide concentration are given. 3.2.2

火花突合熔接せる鋼棒の後熱について(第3報)

When low chromium steel bars (C 0.43%, Cr 0.99%) are flash-butt-welded, the weld metal and heat affected zone show coarse structure containing martensite and troostite. The degree of decarburization of weld metal is smaller than that of low manganese steel bar.If these parts are postheated at about 800°C with an electric furnace, the very hard microstructure in these parts, martensite, disappears and fine sorbite or granular cementite appear. Accordingly the improvement of mechanical properties are observed. In the case of postheating with a flash-butt-welder, the postheating at about 800°C is also suitable.

炭化珪素及び塩化アンモニウム混合剤による珪素拡散について

This siliconizing experiment is carried out by packing the low carbon steel or high carbon chromium steel in a mixture of silicon carbide and ammonium chloride at the temperature of 800∼1100°.In this siliconizing experiment, the rate of diffusion depends on the temperature, the time and the amount of the ammonium chloride.The exact mechanism of this reaction is not clear.But it is believed that the decomposition of ammonium chloride liberates the silicon chlorides from the silicon carbide in the gassy form, and the silicon chloride into the steel to be treated.

International association for testing materials

The new low-chromium steel grades T/P23 and T/P24 are candidate materials for components of ultra-supercritical power plants, and as potential replacement materials of conventional low alloy ferritic steels such as T/P22 in older plants. Higher creep strengths relative to that of T22 were obtained by additions of tungsten, vanadium and niobium in steel T23, and titanium and vanadium in steel T24. In addition, the new grades have the advantage that they do not require PWHT due to the lower carbon content of these steels. Long-term creep performance, microstructural evolution, welding characteristics and other properties are however not fully understood. For example, recent experience on the use of T23/T24 materials showed that stress corrosion cracking (SCC) and stress relief cracking can be major service concerns for such steels. In this chapter, welding and weldability data, including weld repairs, and the types of cracking that can occur in low alloy steel weldments, have been examined in some detail.

Flow Characteristics of Special Fe-Ni-Cr Alloys and Some Steels at Elevated Temperatures

Abstract In this paper the authors give the results of “creep” tests at different temperatures for three groups of alloys. The eleven metals in the first group included commercial alloys of nickel, chromium, and iron, both with and without tungsten, and low-chromium steels containing also tungsten, vanadium, or molybdenum. The second group comprised two carbon steels, a 3½ per cent nickel steel, and two low-nickel-chromium steels which were tested only at 700 deg. fahr.; the twelve alloys of the third group were melted in a high-frequency induction furnace and their compositions were selected to show the general trends at 1000 deg. fahr. in the load-carrying ability of castings of the nickel-chromium-iron system. A metallographic study of the creep-test specimens revealed inter-crystalline weakness in some of the wrought nickel-chromium-iron alloys, especially at temperatures between 1160 and 1390 deg. fahr. A study was also made of the effect of deformation in the creep tests at different temperatures on the hardness and impact resistance of a chromium-vanadium steel at atmospheric temperatures.