Effects of Phosphorus on the Annealing Texture, Plastic Anisotropy, and Mechanical Properties of Low-Carbon Steels

The effects of phosphorus on the annealing texture, plastic anisotropy, and mechanical properties of low-carbon steels containing 0.11 percent manganese have been studied. Both vacuum-melted and air-melted heats, with phsophorus additions up to 0.12 percent, were used. Results show that with a cold reduction of 80 percent, followed by annealing at temperatures in the range 710 to 820°C, the plastic strain ratios, rm and ∆r, as well as the strength of the steels were substantially improved by phosphorus. Annealing at the intercritical temperatures 780 and 820°C further improved the strain ratios. The strong tendency for phosphorus to segregate at the subgrain and grain boundaries is believed to have played an important role in controlling the formation of annealing textures in these steels.

The Influence of Nitrogen and Certain Other Elements on the Creep-Rupture Properties of Wholly Austenitic Type 304 Steel

Experimental heats of Type 304 steel, compositionally balanced to be wholly austenitic and thus simulate the material used to produce seamless superheater tubing, were prepared to determine the influence of selected elements on the creep-rupture properties of this steel and thereby assess their possible contribution to the improvement in the elevated temperature properties which has been noted over the past years. Nitrogen is shown to increase the rupture strength at 1200 deg F of the wholly austenitic laboratory heats to a pronounced extent. Furthermore, almost the full effect of nitrogen was obtained after heat-treating at temperatures as low as 1750 deg F. Rupture strengths also increased with increasing carbon content although heat-treatment above 1750 deg F was necessary to obtain the maximum strengthening effect from the higher levels of this element. Nitrogen was a somewhat more effective strengthener than carbon, the rupture strengths correlating with (%C) + 1.25 × (%N). Small amounts of titanium, aluminum, boron, copper, and molybdenum had no or at most only minor effects on the properties. More than 0.1 percent manganese was necessary for good rupture properties but otherwise had little effect at levels up to at least 1.5 percent. Published data for commercial heats fitted the correlation developed from the laboratory heats. The generally higher level of the rupture strength data for Type 304 austenitic steel published since the early 1950’s appears to be closely related to higher levels of nitrogen. The data indicate that it is extremely important to control nitrogen content to obtain expected creep-rupture properties at 1200 deg F.

Inhibition of Corrosion of Commercial Aluminum In Alkaline Solutions

The corrosion rates for commercial aluminum, containing 4 percent manganese and 3 percent iron, have been determined in sodium hydroxide solutions under different conditions. The inhibitor efficiencies have been calculated for the following substances, the efficiency decreasing from 90 to 60 percent in the order: agar-agar, gum-acaciae, dextrin, gelatin, glue. Corrosion potentials have been measured with and without dextrin inhibitor, and cathodic and anodic polarization studies made. The results show that the dissolution of the metal is electrochemical in character. The corrosion process appears to be under mixed control with predominance of action of dextrin inhibitor on the anodic areas of the metal surface. 6.4.2, 4.3.3, 5.8.2

Behavior of AZ 63 Alloy and Magnesium—1 Percent Manganese Alloy Anodes in Sodium Chloride Electrolyte

The anodic behavor of AZ63 and magnesium-1 percent manganese alloy anodes was investigated in a manner similar to that in a previous study with pure magnesium. It was found that the solution mechanism for the dissolution of magnesium alloys is substantially the same as for pure magnesium. 3.8.3

Inhibition of Titanium In Fuming Nitric Acid

Storage tests were conducted to determine the effectiveness of oxygen in inhibiting the corrosion reaction of titanium in fuming nitric acid (FNA). In these tests, which were of 28 days duration at a temperature of 30 C, the samples investigated were ½-inch squares (0.020 inch thick) of commercially pure titanium (75A) and a binary 8 percent-manganese alloy (C110M). The specimens were stored in Teflon-lined aluminum pressure vessels at 50 percent ullage. The pressure vessels were of the following types: vented to the atmosphere, sealed with air in the vapor space, sealed with oxygen atmosphere in the vapor space, and equipped for a 1-ml/minute oxygen flow through the vapor space. Results of the investigation indicated no inhibition of titanium corrosion by oxygen, but confirmed the inhibiting effect of a water content of 1 to 2 percent by weight in the FNA. 4.3.2