Kinds Of Carbon Steel Research Articles

時計用發條鋼の研究(第1報)

The authors, taking samples of two kinds of carbon steel containing 1% carbon obtained from “Mass” magnetic sand and iron scrap only, examined the physical properties due to heat treatment as time piece spring. The proportional limit, elastic limit and yielding point for equal tensile strenrth of those steels which are quenchel in water or oil and temoered are higher than those which are austemperel. The impact value of steel obtained from Miss'' m_??_gnetic s_??_nd is higher than that of the steel made by iron scrap only. Furthermora, the author, c_??_rried out a series of exper ments with thin plates of 0.4mm by cold rolling and studied the physical properties brought about by different, heat treatments, and also tested their work hardening owing to cold rolling and then softening by an nealing. The steel being subjected to cold rolling after heat treatment increases its' hardness and tensile strength, but the toughness is greatly decreased.

軸受性能について(第6報)

The results of wear test on some kinds of carbon steels and cast iron in combination with carbon steels and cast iron prove that the wear loss is proportional to the hardness variation of the rubbing surface. The hardness of rubbed surface is measured by the microscopic Vickers hardmeter on 100 gram load. The surface hardness of steel increases on the low carbon side and decreases on the high carbon side. This phenomenon resembles the oxide film hardness reported in the 2 nd report. The oxide film generally protects abrasion but free oxide flakes or grains accelerate wear and soft material that produces hard oxides can easily wear out harder steel. As a consequence of the inordinate hardness increase on the rubbing surface of carbon steel In certain conditions, it is supposed that there are not only simple plastic deformation and oxidation but also quenching by radical heating and cooling.

齒車用炭素鋼の磨耗に關する二,三の研究

High carbon steels, which were hardened and tempered, are generally used for gear material. Several papers, however, have reported that steels of high hardness do not always show high resistance to wear. In this investigation the influence of carbon content and heat treatment on the mechanical properties and the wear resistance was studied. The specimen used was six kinds of carbon steels between 0.2 and 0.7% carbon. Abrasion tests were made by means of Amsler Testing Machine. The results of the tests maybe summarised as follows: In case the heat treatment was done so as to possess the Shore hardness 60, lower carbon steels showed superior properties both in tension and impact tests to the higher carbon steels. Resistance to wear is much affected by the method of combining test pieces and the pressure given upon them: an increase of carbon content is not the first condition for improving the resistance to wear; on the contrary, it has become evident by this investigation that a decrease of carbon content results in an increase of resistance to wear, so far as the Shore hardness is 60 or so. In other words, martensitic steels, even if low carbon, have higher resistance to wear than carbon rich sorbitic steels.

鋼の熱脆性に及ぼす熱処理及び成分の影響

There are various kinds of heat-brittleness of steel, these being more or less related to the cracks due to the cooling or forging of steel, the defects of steel at high temperatures, etc. The characteristics and causes of the heat-brittleness are not yet fully revealed. The author, therefore, carried out experiments on the relation of the heat-brittleness and heat-treatment, using two kinds of carbon steel and one kind of nickel-chromium steel. It was thereby concluded, that (1) the precipitation hardning of super-saturated cementite disolved in cr iron at a temperature below the transformation point becomes the cause of brittleness at a lower temperature independent to the blue-shortness, (2) the temperature at which the blue shortness occurs is invariable to the cooling velocity provided that martensite is not formed, and (3) the so called secondary brittleness appears only when the crystal grain is coarsened by annealing at a high temperature such as forging temperature. Next, experiments were carried out on about 30 different special steels. It resulted in the conclusion that (1) all the elements, C, Ni, Cr, Mo, Mn, Si, etc, augment the secondary brittleness, particularly the effects of C and Mn being most remarkable ; (2) Cr and Mn shift the secondary brittleness to a lower termperature; (3) there are a special brittleness near the transformation point which seems to be related to Si and Mn content but even in the steel of the same compositions the special brittleness occurs if the melting differs.