US1974115A - Alloy steel railway track member - Google Patents

Description

Patented Sept. 18, 1934 UNITED STATES ALLOY STEEL RAILWAY TRACK MEMBER Charles E. MacQuigg, Flushing, N. Y., assignor to Electro Metallurgical Company, a corporation of West Virginia No Drawing. Application December 31, 1931,

Serial No. 584,275

3 Claims.

This invention relates to new and improved chromium steel alloy railway track members.

Material for railway rails, frogs, switches and crossings should have the strength and toughness necessary in structural members, together with great hardness and resistance to wear, to enable it to withstand the abrasion and pounding to which it is subjected by the rolling stock. Heretofore various steel compositions have been experimented with in an effort to combine these qualities with sufficient cheapness and workability to be commercially practicable, but a fairly high carbon steel has been found to be most generally suitable, and has been universally adopted as a compromise.

It is well recognized that chromium has the property of imparting to a steel a certain toughness and depth of hardness. Chromium steel has therefore been suggested as a material for track members, but the chromium content has always been limited to about 1%. When more than 1% to 1.5% of chromium is added to rail steel of the usual carbon content the air hardening properties of the steel become so pronounced that the rails are too hard and brittle to meet the drop test specification and the requirements in service. While the properties of such rails could be improved by heat treatment, their manufacture is not commercially feasible.

In the type of high carbon steel rail now in general use, it is customary to limit somewhat the carbon content in order to prevent dangerous brittleness which might result in rail fracture. This is accompanied by a certain lack of hardness, so that the majority of rail troubles arise as a matter of surface deterioration. It has been proposed to restore the wearing surfaces and battered ends of such rails by building up the worn surfaces or ends with a suitable metal fused thereto by the electric are or the oxy-acetylene welding torch. Chromium steel has also been suggested for this purpose, wherein it is formed into a welding rod containing chromium within a preferred range of 0.75% to 1.50%. In order that such steel may readily be rolled into the form of a welding rod, the carbon content is kept low, anddoes not exceed 0.60%. In building up the surface of a rail with this steel an excess of acetylene is used in the welding torch flame, whereby the carbon content of the molten chromium steel is increased, and the hardness and wear resistance of the deposited metal becomes considerably greater than that of the rod. Without the use of this excess acetylene in'the welding flame, the deposited metal is too soft and.

tends to crush and flow under pressure of the rolling stock.

In accordance with my invention I have provided a chromium steel composition which may be formed directly into a rail or other track member by the usual rolling procedure of a commercial rail mill. The steel can be made in the ordinary open hearth furnace and rolled without further heat treatment, to produce a rail with an exceedingly high degree of hardness, toughness, 05

and resistance to wear, and without the brittle ness and other detrimental qualities which heretofore have almost entirely prevented the use of chromium steel for this purpose.

I have found that by increasing the chromium content of rail steel to a point above that heretofore considered practical for a commercially workable alloy, the Wear resistance and toughness of the resulting steel may be greatly increased. At the same time the metal may be worked in the manner usually employed in the forming of rails if the proper balance of chromium and carbon is maintained. In a preferred composition the chromium is present in an amount of at least 2.50%, and the carbon does not exceed 0.40%. As the, chromium is increased to the upper limit found to be suitable, approximately 3.50%, the carbon may be reduced, reaching a lower limit of approximately 0.22%. For example with a chromium content of substantially 2.75% to 3.25%, the carbon will vary between about 0.25% to 0.35%. A more specific composition found to be highly satisfactory contains substantially 3.00% chromium, substantially 0.32% carbon, and the usual percentages of manganese, phosphorus, sulphur and silicon now commonly used in a rail steel namely, about 0.5% to 0.9% manganese, up to about 0.04% phosphorus, as little sulphur as is commercially practicable, and about 0.15% to 0.40% silicon.

A chromium steel rail made in the manner of my invention has greater resistance to wear than those rails armoured with a low chromium steel, in the manner previously referred to. The procedure of manufacture is no more involved than that employed in the making of the high carbon steel rails now in common use. Actual tests have shown that a rail of my composition will outlastby several times the ordinary carbon steel rail, especially at those points in a railroad where due to great density of traffic, high speed of trains, or other conditions, the wear on rails is unusually severe. The ever present danger of breakage, which frequently occurs in the carbon steel rail, is almost entirely eliminated in the one of chromium steel due to its exceedingly high degree of toughness.

The following tables show the results of actual tests made on my chromium steel rail as compared with other known types of rails. In the first table the Brinell hardness is given for a variety of rail compositions, and the second tabulation shows the drop test results on three of the tainly not show the same combination of duetility, stiffness, and hardness (in other words, toughness) that are shown by the data for the 3% chromium steel rails of my invention.

My interest in this new alloy steel has been directed primarily to its use as a track member, since I have found it to be especially well adapted for that purpose. However, the specific properties of the steel itself as herein shown, may

specimens indicated in the first table. also suggest its use for other purposes. For ex- TABLEI Brinell hardness of rails (as rolled) Type kgf 0% Mn% 1 51% 01% 01% B. H. N

Plain carbon 1. 1 0.69 0.88 033 027 0. 23 241 0 2 0. 7a 0.87 022 .030 0. 2a 248 Medium manganese 3 0.57 1. 42 .022 043 0. l9 255 Do 4 0. 52 1. 57 .025 .040 0. 22 286 5 0.51. 0.90 .041 .040 0. 20 0. 04 209 0 0. 01 0. 95 037 .039 0. 24 0. 97 293 Do. 7 0. 04 0.85 .029 .030 0. 21 1. 02 320 3% chromium s 0. 25 0. 00 .013 .020 0. 25 2.89 370 TABLE II Drop test for rails (as rolled) elongation per inch Permanent figi Wt. of rail sbg Supports g ggg set in Total Inches 1st in. 2nd in. 3rd in. 4th in. 511101. 6th in.

Feet Feet Lbs. 2 l27#/yd. 20 4 2,000 1 .70 2 2 a a 2 2 14 2 1.25 a 4 5 5 4 a 24 a 1.70 5 0 7 0 5 4 as 4 2.20 0 7 9 s 7 5 42 3 127#/yd. 20 4 2,000 1 .85

2 1.45 a 2.05 7 s s 7 0 4 40 4 2.00 7 0 s s .0 5 43 5 3.35 7 10 9 9 7 5 47 a 130#/y 22 4 2,000 1 .50 2 3 a a 2 2 15 2 1.10 4 5 0 5 5 4 29 3 1.50 5 7 s 9 7 5' 41 4 2.00 7 9 10 10 s 5 49 5 2.40 9 11 11 11 0 7 5s 0 2.80 10 12 12 12 10 7 03 These data show the normal hardness of plain carbon steel rails, and that of medium manganese steel rails, the latter of which are now being used in increasing quantities. the rapid increase in hardness of 1% chromium rails with increasing carbon content, illustrating the air-hardening tendency of this steel, as referred to previously in the specification. With a higher chromium content at this percentage of carbon, the hardness would increase even more rapidly and the rail would become so brittle that it would fail under the drop. The much higher hardness of the 3% chromium rail of low carbon content, as disclosed by my invention, is plainly evident.

lhe drop test figures show normal results for the plain carbon and medium manganese rails of these types, and the higher ductility of the 3% chro 1m steel rails is clearly brought out. Considering the high hardness in this rail the ductility is remarkable, as a plain carbon or 411edium manganese rail of similar hardness would very probably break under this test on the first drop. Even with this high ductility the 3% chromium rail shows a greater stiffness than the others, which is highly desirable. No drop test data are available for the l chromium steel rails shown in the hardness table, but they would cer- It also shows ample other uses which have been proposed are in the making of shovels, railway tires and forged wheels, and in general any use which requires a combination of resilience and toughness with a high degree of hardness.

While specific compositions are given herein to illustrate my invention, it will be evident that modifications may be made which are within the spirit of my disclosure. This is especially true with reference to the elements other than chromium and carbon which may be present in the rail composition. As mentioned manganese, phosphorus, sulphur and silicon are preferably present in the amounts usually found in the ordinary rail steel. Certain variations in the percentage of these materials may be found desirable. In some instances there may also be an advantage in adding small amounts of one or more of the elements nickel, zirconium, molybdenum, vanadium and copper. Such additions and variations are all within the scope of my invention, which should not be limited other than as defined in the appended claims.

I claim:

1. A rolled wrought railway rail consisting wholly of a chromium steel alloy having substantially the composition: 2.50% to 3.50% chromium, 0.22% to 0.40% carbon, manganese in 159 3. A rolled wrought railway rail consisting wholly of a chromium steel alloy having'substantially the composition: 3% chromium, 0.32% carbon, 0.5% to 0.9% manganese, 0.15% to 0.4% silicon, the remainder iron.

CHARLES E. MACQU'IGG.