US2002932A - Steel for railroad rails, wheel tires, plank piles, and other objects - Google Patents

Description

Patented May 28, 1935 UNlTE-D; STATES PATENT OFFICE s'mm. i on RAILROAD nma'wnn TIRES, PLANE OBJX'EGTS PILES, AND OTHER No Drawing. Application becemberll. 1931.,

Serial No. 580,500. 1930 This invention relates to a steel suitable for objects subjected to heavy wear.

The following fundamental requirements have to be met in the case of railroad rails:

1. The rails must have such a great mechanical strength that they are able to furnish sufficient resistance to stresses during service caused by wheel pressure, shocks and the like. For this purpose an adequately high elastic limit is neces-- sary, in order .to avoid the rails spreading under the wheel pressure, moreover an adequately high resistance to repeated shock stresses is also required, that is to say, a high resistance to impact stresses and prolonged stresses. Experience has 15: shown that these requirements were first met by steels having a high elastic limit and good toughness together with a moderate tensile strength. 2. The resistance to wear of the rails must be so great, that the least possible loss due to wear takes place under the action of the rolling and sliding friction of the wheels travelling thereover.-

is furnished by the examination under the specification for the contract. This examination also extends to ascertaining whether the steel possesses adequate resistance to impact by. means of the rail impact test and proving whether thesteel is sumciently hard and strong mechanically by measuring the Brinell hardness or by means of the draw-test.

It is difficult to fulfil these manifold requirem'ents-without detrimentally aifecting the other properties to a certain extent. The requirements as regards high toughness together with high mechanical strength counteract one another to a certain extent. The requirement as regards high resistance to wear cannot be attained in view of the foregoing two criteria, since resistance to wear does not run parallel in any way to hardness, elastic limit or tensile strength. 50 It is therefore a question in view of the practical requirements of the case under consideration to evolve an optimum hardness, elastic limit, toughness and resistance to wear with the maximum economy. The means of effecting this are various. It is well known that the-tensile strength In Germany December 12, 2 Claims. (01.75-1) and elastic limit may be increased by increasing the carbon content, the 'manganese content, the silicon content and also by the addition of other elements suchaschromium, nickel and the like, the latter however not coming into consideration 5 in the present casefor' economic reasons.

It is also known that increasing the content of manganese and also that of phosphorus increases the resistance to wear. Nevertheless a considerable increase in practice of the resistance to wear can only be produced. by adding manganese in v such quantities that the toughness (determined by the elongation during thefracture test, behaviour during the impact test and the notch-bar toughness) begins to decrease too rapidly. Hitherto no use at all could .be made of the effect of the phorphorus increasing the resistance to wear,

. since, in the usual composition of the rails hav-' ing phosphorus contents below about 0.08% practically no noticeable influence occurs and any increase of the phosphorus content above 0.1%

renders the rails too brittle, that is to say, too

sensitive to shocks. For these reasons hitherto the steel works kept the phosphorus content at about 0.08% as the upper limit. I

Tests made by the applicant have now shown that the property of phosphorus of increasing the resistance to wear of these steels can be made possible by adding this element in quantities of 0.08% and more and at the same time considerably reducing the carbon content .blows usually after sagging to the extent of more than 140 ms. The elastic limit is sufllciently h, being more than 36 kg. per mm., to avoid the rails spreading even when the wheel pressure is increased and the elongation and the notchbar-toughness are of such a high order that there is no danger of the rail being affected detrimentally by impact or shocks. The resistance to wear is increased to such a great extentby the combined action of manganese and phosphorus, that this steel can be compared directly with the steel rails which are known to be resistant to wear and which possess a tensile strength of more than 2 '15 kg. per mm., the elongation however and in melts are given in the following table.

particular the notch-bar toughness of the steel or the present invention being greater than in the ordinary steel for rails having thisstrength. In order to bring about'this object it is necessary-to keep the carbon content low and it possible below 0.20%, the manganese content being kept within. the limit of about 0.6 to 1.6% and the phosphorus being above 0.08% up to about 0.25% whilst the silicon content amounts to between 0.1% and 0.6% and the copper content to about 0.25 to 1.0%

By said small content or copper the uniiormity of the structure and the mechanical strength properties oi this steel is increased. The copper content as is known also increases the resistance to corrosion and rusting oi the steel, whichis of considerable importance in service when the steel is used in the presence of corrodve media for example when the rails are laid in tunnels.

The steel may contain in addition thereto the usual accompanying elements, but i! sulphuris present the content thereof shall be preferably kept low so as to lie from trace to about 0.12%.

Thebal ceoithealloyconsistssubstantially of iron. It may be possible, however, to use some further alloying additions in known quantities and for known purposes. Such further alloying elements are comprised by the term the balance substantially iron"; provided, however, that the character of the alloy as described is not materially altered by such iurtheradditions and that the elements mentioned are present in the amounts specified.

The tensile strength properties and the resist- .ance to wear of such rails were determined exhaustively from a large number of melts, the apparatus oi. Spindel and Mohr and liederhaii being employed for determining the resistance to wear.

Examples oi. the results of several tests on rail Theimpacttestprescribedbytheqerman State Railway in their specification for steel was passed by'these rails altogether in a very satisfactory manner, and even when this test was made more stringent, fracture only occurred after ordinary carbon rails having a tensile strength of 70mkg. per sq. mm. had already broken underthe test. As' may moreover be seen from the tablere'sistanoe to wear is also considerably higher than that oi. other rails oi' the.

same mechanical strength, values beingv shown whichare only obtainable in carbon steel rails ha atensiiestrengthofaboutfikgper whenconsiderin'gtheresultsoitheweartest on the Mohr and l 'ederhail machines it should be mentioned that from experience rails having a decrease in-wei'ght duringthe testoi less than 1.1 grams are termed "wear resistant. The rails. produced according to the process of the present invention exhibit throughout a 'decrease in weight 0! below 1.1 gram.

The permanent resistance'to bending which is also important for practical service was ascertainedbymeansota'plursiityoi'testsonthe Schenck permanent bending machine, Imder loadsoiatleast 30kg.persq.mn1.andonthe lngtestpfeceswhieh weresubmittedtotwists, values higher than 27kg. per sq. mm. were invariably obtained. Ll'he steel thus very .highpermanentstrengthatthesametimevery Tsnnn 'CoM osia'onandotrsngthpropsflissoIrafleSN .M I! m WM Stool v I W s Mob: Elastic mm. M Notched $111 and 0 Guile limit mu m tenacity 0!. mm L cutln' deans.

Pcr- Pa- Per- Pcr- Per- Per i...- Per on out can! seat rent out Kflmmw. Buoyant. out eel Analog-am. llsu. Grass 1.- 0 3011 0.00 0.02 0.14 0.0a 002 :1 01 1s 1s a 4: 1.4 (Com 0.42 0.15 0.00 000 0.00 40 1s 1s 10 2 41 1.1 son.

r-g n 0.11 0.00 1.00 0.11 0100' it "o1 24 to s an 0.0

S 4 0.01 0.21? 1.02 000 0.40 0.0 u as as s: 11 as as 014 040 120 0.10 0.40 4s 02 10 v u s as 4 0.1; 0 010 040 0.18 0.40- is 02. 11 4s 0 a1 0.1 012 0.40 1.90 1; 050 0.10 42 so as as s .40 0.0

l'ormoitestpiece l0x10x00witbacircularnotch5 mms. deep-2m. e Lengtholcutasthea 0 din cutsunderapressure' oiiikgs.,260completomolutionsn=25.

1 Decrease alter 200,000 revoiutions n n dsr an applied prsssurs'oi 100 kgs.; 1% slip, 425 pa minute.

' In spite of the relatively low carbon content content was in to'over 0.1%, the silicon the elastic limit oi! the steel is above 40 kg. per sq. mm., 1. e. it possesses values which could only be produced in an ordinary steel having-a carbon content of more than 0.5%.

average of 34 kg. per sq. mm. Even when testcontent being increased at the sametlme. The

tires plank-pilesnnd particularly for sea walls 7 and other steel parts whichare subjected to wear. 1 Having-now aseer-' tained the nature of my said invention-and in what manner the same is to be performed, I declare that what I claim is:

1. A steel for railroad rails, wheel tires, plank- 'piles and other objects which are subjected to heavy wear, said steel containing about 0.05 to 0.20% of carbon, about 0.08 to 0.25% of phosphorus, about 0.1 to 0.6% of silicon, about 0.6 to 1.6% of manganese and about 0.25 to 1% of cop- 10 per and the balance substantially iron.

2. A steel for railroad rails, wheel tires, plankpiles and other objects, which are subjected to heavy wear, with a sulphur content of from trace to about 0.12%, said steel containing about 0.05 to 0.20% of carbon, about 0.08 to 0.25% phosphorus, about 0.1 to 0.6% of silicon, about 0.6 to 1.6% of manganese and about 0.25 to 1% o! copper, the balance consisting substantially of iron.

HERBERT BUCHHOLTZ.