US2557862A - Internal-combustion engine valve - Google Patents

Description

June 19, 1951 w. c. CLARKE, JR

INTERNAL-COMBUSTION ENGINE VALVE Filed Nov. 19, 1947 HOCH/'OBGOS/SNVHS NI S501 .xLHSIEIM IN VEN TOR.

Vl E N W A S m Patented June 19, 1951 INTERNAL-COMBUSTN .ENGINE'VALVE William C; Clarke, Jr., Dundalk; `Md., assigner to ArmcofSteelCorpm-ation, azcorporaton iofOhio Application November 19, 1'94'1, 'Serial`N`o. 786,963

1 Claim. (CL75- 128) l This invention relates in 'general "to 'stainless steel, and more especially tor-stainless steel rarticles having resistance to leaded fuels and their combustion products.

2 'of leaded fuels; Among the lead compounds so often 'causing' substantial ldetriment are tetraethyl'lead lor other leaded fuels and 'their combustion products containing leadV oxide, or the An object of my invention is the provision of i5 a durable, corrosionresistant stainless steel'which A further intensifying factor in high temperais easily wrought, which is `or good impact ture engines as of the internal combustion type, strength and which is Well suited incomposition depends upon Whether the particular valve emfor reliably resisting corrosion by the combusployed is on the intake or exhaust side. In avertion products of leaded fuels. l age passenger cars, thev temperatures encoun- A further object of my invention is thatfof'protered by the valves frequently mounts up to 700' viding high temperaturev stainless steel articles, F. von the fuel intake side of the. engine and as as for example internal combustion enginevalves high'as 1100c F; to 1450?' 'li'. or more on the exand valve parts, turbine parts such as nozzles, Y haust side. These temperatures usually are quite and a host of other products which over long 1'5 a'bit'higher in truck or aeroplane engines, espeperiods of use endure thev corrosive effects of cially for the exhaust side of the engine. leaded fuels and their combustion products. Low alloy steel Valves and valve Yparts when Other objects in part will be obvious andv in considered'to'day for high temperature engine use part pointed out hereinafter. and the like, are in most :instances found tojoe The invention accordingly consists in fthe :comunacceptable if for no other reason than bei-ng bination of elements and composition'o'f ingredivulnerable to scaling and corrosion under the entsand in the articles -`fashionedthereof as deintense heat of operation and general inability scribed herein, the scope vof the application of to withstand the temperatures. The scaling usuwhich is indicated in the following'claims. y ally prevents proper seating, and instead permits The single figure of the accompanying "drawaleakage `of hot gases, which in turn raises the ing is awgraph `illustrating 'certain properties of valve head temperatures, a combined action my steel. which of course results in quickly burning away As conducive to a clearer understanding ofcerthe head. Leaded fuels and their combustion tain features of my invention, it may be noted gases greatly accentuate this action.. at this point that stainlesssteelby generalde'ni- 30 An outstanding object Aof my invention is the tion contains about 10% tov3'5'% chromium'with provision ofstainless steel articles and products or without nickel and with or `without additions which a're'highly resistant tothe corrosive eiects of other ingredients -for special purposes, the'reoffl'ead .oxide and the like while hot, and which mainder being substantially all iron. otherwise have good properties for resisting ox- There are constantly increasing demands for i'dation, corrosion and mechanical effects. stainless steels which are capable of withstand- .Referringnow more particularly to the pracing the effects of the combustion products of tice of .my invention, I nd that in a wide range leaded fuels under conditions of heat. These of chromium-nickel stainless steels, it is the eleneeds particularly apply to exhaust 'valvesfor I y ment sulphur which has a marked effect upon internal combustion engines, turbine parts, fun- 40 the` resistance of the steel to corrosion by lead nace parts and equipmentyand the like, Where compounds when the element is controlled to leaded fuels and their combustion products areproper and critical amounts. The .quantity of encountered. sulphur .considered critical lies between about Whether operating conditions are more or less 0.15% and 0.50%. Higher amounts may occur, severe, many of the lheretofore known stainless butbeyond 0.50%, hot working diiiiculties usually steels, despite having a varietyof valuablepropcan. be expected and the rate of further improveerties,rpit and corrode too readily-for practical use ment in resistance to lead-corrosion decreases. in the presence of the lcombustion products of The critical amounts of sulphur give a remarkleaded fuels. This occurs even where certain of able counteracting eifect upon nickel and the the steels are of corrosion rresistantquality sofar like, which otherwise I nd tend to diminish 3,5 other Corrosive Yeffects fare yQ()ncepned `qgfml'ule'SStaIlC'e Of SteeltO Ie'ld-OXlde "COllOSOIl, sive of having resistance to acids such as nitric The stainless steels of the general character or sulphuric acid, fruit acids, body salts and iridicated'which I'provide, more particularly concorrosion in ordinary atmosphere as 'wellas "at tain 4about 0.10% to 1.25 carbon, 12% to 25% high temperatures. chromium, 4% to 35% nickel, sulphur preferably In the instance of stainless steel valves, many vfrom 0.715%- to 0.50%, and the remainder subhave appreciable resistance to oxidation even at stantially all iron. Such Velements as aluminum, high temperatures, but the resistance usually is silicon, manganese, tungsten and-molybdenum not so favorable where oxidation, pitting and cormay be included in'small amounts. rosive attack are intensined by the current use B0 vMy chromium-nickel stainless steels all are Well suited for resisting attack from hot lead oxide such as in the combustion gases resulting from the burning of leaded fuels, the latter fuels illustratively including tetra-ethyl lead.

Within the composition ranges noted the sul.- phur and other elements such as carbon, chromium, nickel, and silicon, preferably are so cor''` related in amount as to achieve properties of hot hardness, resistance to scaling and lead corrosion, also resistance to impact and fatigue, and resistance to wear, all needed in high temperature valve steels and at least for certain types of valves. I accordingly provide these steels, and high temperature articles and products of the steels, by hot Working and machining the metal into such products as exhaust valves and valve parts for internal combustion engines, gas vturbine nozzles and related turbine parts and Superf charger components.

The accompanying drawing illustrates the effects of different amounts of sulphur on corrosion resistance of stainless steel in molten lead oxide. The samples contain -about 0.095% carbon, 20.68% chromium, 15.12% nickel, with dif- :tering amounts of sulphur, and the remainder substantially all iron. The basic points along the curve in the drawing are derived from a series of steels having the composition just noted and respectively containing 0.047% sulphur, 0.220% sulphur, 0.488% sulphur and 0.822%. sulphur. The Weight losses of these samples .in molten lead oxide at 1675D F. in terms of grams per square decimeter per hour appear below;

TABLE I Weight loss. gms. per sq. dem. per hr.

sample Per SCent recom From these valves, particularly the tests on samples B, C, and D, and others determined by interpolation, it is clear that a great improvement in corrosion resistance is had when the sulphur is increased to about '0.15% and on up to about 0.50%. Beyond 0.50% the sulphur still improves the resistance to molten lead oxide, but to a less marked degree and the hot Working properties usually suffer.

AS a further illustration of my invention, samples of stainless steel containing 0.40% carbon, 22.94% chromium, 4.87% nickel, 2.92% molyb-V denum, 0.75% manganese, 0.57% silicon, differing amounts of sulphur, and the reminder iron were subjected to corrosion by molten lead oxide Ejject of sulphur content of 24-5-3 chromiumnickel-molybdenum stainless steel on corrosion in molten lead oxide Per gent Weight loss, y

dem. per hr.

gms. per sq.

TABLE III Effect of sulphur coutent of 21-12-2 chromiumuzckel-mangauese stainless steel ou corrosion in molten lead oxide Weight loss, gms. per sq. dem. per hr.

Sample Per SCent It is noted that with the high manganese content considerably greater sulphur content is required to achieve the-desired resistance to co1'- rosion.

Thus it will be seen that in -this invention there are provided a wide variety of stainless steels, and stainless steel articles and products, in which the various objects noted hereinbeiore together with many thoroughly practical advantages are successfully achieved.V It will be seen that the steels and products are well suited for resisting corrosion by the combustion products of modern fuels.

As many possible embodiments may be made of my invention and as many changes may be made in the embodiments hereinbeiore set forth, it will be understood that all matter described herein is to be interpreted as illustrative and not as a limitation.

I claim:

Chromium-nickel stainless steel internal combustion engine valves having substantial resistance to corrosion in the presence of the combustion products of leaded fuels, and containing approximately 0.10% to 1.25% carbon, 12% to v25% chromium, 4% to 35% nickel, at least aboutV 0.15% but not over 0.50% sulphur and the remainder substantially all iron.

'WILLIAM C. CLARKE, JR.

REFERENCES CITED The following references are of record in the file of this patent: *Y

UNITED STATES PATENTS Number Name Date 2,140,501 Arness Dec. 20, 1938 FOREIGN PATENTS Number Country Date 359,326 Great Britain Oct. 22, 1931 392,648 Great Britain May 25, 1933 OTHER REFERENCES Metals Handbook, 1939 edition, page 41, published by the American Society for Metals, Cleveland, Ohio.

The Iron Age, June 28, 1934, page 18, published by the Chilton Co., Philadelphia, Pa.

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