Effect of Nitrogen and Few Other Elements on Strain Aging of Steels

Many investigations were carried out on the strain aging of steels but few were reported on commercial steels. In succession to the work on the effect of nitrogen on the strain aging in steels, the effects of Al, Ti, Si, Mn, As and Cu were examined

Influence of Nitrogen on the Low Temperature Brittleness of steel

The influence of nitrogen on the low temperature brittleness of steel has been investigated. In particular,it was systematically studied under the coexistence of other elements which have a chemical affinity for nitrogen . Among those studied, Ti, Al and V have a strong affinity , Si and P a moderate and Cu, Sn and As a weak affinity . All these alloy- ing elements were found first to diminish the effect of nitrogen by forming nitrides or reducing the solubility of nitrogen in a-iron, and then to reveal their own effect with increasing content

Effect of Nitrogen and Other Alloying Elements on the Low-Temperature Brittleness of Steel. III : Nitrogen Fix and Nitrogen in Quench-Tempered Steel

The following have been made clear by examining the effect on the low-temperature brittleness of steel of aluminium and titanium as the elements fixing nitrogen. (1) The effect of nitrogen decreases with the addition of aluminium and titanium ; (2) in the steel containing 0.32% of carbon, AlN lowers a little the pulse value of steel, but has little effect on the transition temperature ; (3) unlike the case of adding aluminium, the addition of titanium slightly raises the maximum pulse value and tends to raise the transition temperature ; (4) when the effect of nitrogen on the low-temperature brittleness of the steel containing phosphorus appears relatively large, the addition of titanium clearly improves the low-temperature brittleness of the steel ; (5) the effect of nitrogen can be observed even in the steel quench-tempered, the effect of nitrogen similar to the case of air-cooling appears on slow-cooling after tempering and the aging phenomenon appears on rapid-cooling after tempering ; (6) in both cases, the transition temperature rises proportionally to the amount of nitrogen content

Nitrogen as Alloying Element in Steels. II : On the Effect of Nitrogen on Blue-Brittleness in Steels

To ascertain the effect of nitrogen on the blue-brittleness in carbon steels, usual tensile tests were carried out at temperatures above room temperature up to 300°, and it was found that nitrogen was the principal cause of this phenomenon, although the brittleness due to carbon was seen at a high temperature range in steels containg low nitrogen

Nitrogen as an Alloying Element in Steel : Effect of Nitrogen on Quench-Aging of Steels

The present investigation was carried out in order to ascertain the effect of nitrogen on the quench-aging of steels containing 0.02～0.03 and 0.15～0.20 per cent carbon. The specimens tempered at 700℃ for 3 hours after quenching at 950℃ were requenched at 300～700℃ after heating for 3 hours at respective temperatures and then aged at 30, 50 and 100℃. From the present investigation the following conclusions were obtained : (1) There is a distinct correlation between the nitrogen in steel and the quench-aging ; (2) By the addition of nitrogen stabilizer such as Al or Ti, or by the fusion in vacuum the aging due to nitrogen is reduced ; (3) The specimens containing less than 0.005 per cent of nitrogen revealed aging due to carbon

A collimated jet and an infalling-rotating disk in G192.16-3.84 traced by H2O maser emission

We report H2O masers associated with the massive-star forming region G192.16-3.84 observed with the new Japan VLBI network at three epochs spanned for two months, which have revealed the three-dimensional kinematical structure of the whole \h2o maser region in G192.16-3.84, containing two young stellar objects separated by ~1200 AU. The maser spatio-kinematical structure has well persisted since previous observations, in which the masers are expected to be associated with a highly-collimated bipolar jet and an infalling-rotating disk in the northern and southern clusters of H2O maser features, respectively. We estimated a jet expansion speed of ~100 km/s and re-estimated a dynamical age of the whole jet to be 5.6x10^4 yrs. We have investigated the spatial distribution of Doppler velocities during the previous and present observations and relative proper motions of H2O maser features in the southern cluster, and a relative bulk motion between the two maser clusters. They are well explained by a model of an infalling-rotating disk with a radius of ~1000 AU and a central stellar mass of 5-10 M_sun, rather than by a model of a bipolar jet perpendicular to the observed CO outflow. Based on the derived H2O maser spatio-kinematical parameters, we discuss the formation mechanism of the massive young stellar objects and the outflow development in G192.16-3.84.Comment: 30 pages, 3 figures, 3 tables, to be published in the Publication of the Astronomical Society of Japan issued on 2006 October 2

Corrosion and Erosion of Ferritic Steel by Liquid Bismuth

Static corrosion of Fe-C-Cr alloys and erosion of Fe-C and Fe-Cr alloys due to the contact with liquid bismuth were studied. For the static corrosion test, magnesium as a deoxidant and zirconium as an inhibitant were added into liquid bismuth prior to the immersion of specimens. The erosion test was carried out by applying an ultrasonic oscillation of 20±2 kc in frequency and 15 microns in amplitude. The results obtained were as follows. (1) In Fe-C alloys, when the carbon content increases the degree of static, corrosion becomes less. In Fe-C-Cr alloys, the chromium content enhances the degree of static corrosion. For the inhibition of corrosion the increase of carbon content in the alloy may be necessary. (2) From the erosion test it was found that the surface pits are not due to a chemical corrosion but to a mechanical attack, and that the degree of erosion chiefly depends on the hardness of the alloy

Effect of Nitrogen and Other Alloying Elements on the Low-Temperature Brittleness of Steel. II : Correlative Effect of Nitrogen and Phosphorus

A study was made of the relation of the co-operation of phosphorus and nitrogen to the low-temperature brittleness of steel, and the following results were obtained. 1. The effect of nitrogen was observed in the steel containing phosphorus in raising the transition temperature, being stronger than in the steel without phosphorus. 2. The range of nitrogen content which abruptly raises the transition temperature was in low-nitrogen side, compared with the steel without phosphorus. 3. Phosphorus was an element that makes the low-temperature brittleness greater. It was made clear that the effect of nitrogen was reduced when the nitrogen in the steel was fixed as AlN by adding aluminium to molten steel, and that the degree of reduction of the effect was conspicuous as in low-carbon steel. It was also clarified that when carbon content became larger, the transition temperature rose even if nitrogen was fixed by aluminium, compared with the specimen with 0.003% of nitrogen, because of the effect of aluminium and other phenomena which raise the transition temperature, and that the transition temperature became lower when nitrogen was fixed in the specimens containing phosphorus by adding aluminium, as the effect of nitrogen was great in such specimens

Effect of Nitrogen and Other Alloying Elements on the Low-Temperature Brittleness of Steel. I : Correlation of Nitrogen and Carbon

U-notch Charpy tests were performed with steels containing 0.3 to 0.4% of manganese, 0.15 to 0.25% of silicon, 0.003 to 0.005% of phosphorus. 0.015 to 0.030% of sulphur, 0.003 to 0.019% of nitrogen, 0.03 to 0.82% of carbon and copper in order to clarify the effect of nitrogen and carbon on the low-temperature brittleness of carbon steel. The results obtained were as follows. 1. The transition temperature rises with increasing content of nitrogen and carbon. 2. The effect of nitrogen becomes greater with lowering grade of carbon steel. 3. The transition temperature rises sharp up to about 0.008% nitrogen content, beyond which it rises gradually. 4. The effect of nitrogen is observable in low-carbon α-Fe, but less in hypoeutectoid structure, and not in eutectoid structure