US2380821A

US2380821A - Poppet valve and valve seat for internal-combustion engines

Info

Publication number: US2380821A
Application number: US375246A
Authority: US
Inventors: Walter R Breeler; Jr Gurdon M Butler
Original assignee: Allegheny Ludlum Steel Corp
Current assignee: Allegheny Ludlum Steel Corp
Priority date: 1941-01-21
Filing date: 1941-01-21
Publication date: 1945-07-31
Anticipated expiration: 1962-07-31

Description

July 3l 1945 w. R. BREELER ETAL 2380821 POPPET VALVE AND VALVE SEAT FO INTERNAL-COMBUSTION ENGINES Filed Jan. 21, 1941 AfA/AL Y5/5 0. 0202/0 70% my. 4.0% /0 0.0% ff 7502/0 2.20%

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July-31.1945

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Pennlylvlllll e tion of aspiration :spain zi. un. sea-lai No. 31ans s wl. iss-iss) our` invention relates valves and -vaive seats'for internal combustion engines and particular-lyre which are suitable for useinsuchvaivesandseatsoperating inengines using modern antlknock fuels.

In the drawing, ll'lg.` l is an elevation v iewofa poppet valve for sn internal combustion, engine; Fig. 2 is aplan view of a'valve seatinsert, drawn to a somewhat smaller scale than the valve in While the necessary and desirable physical characteristics of-steels for use in Aengine valves and seatsare well known, theproblem of finding a steel embodying all of the necessary and most of the desirable properties is extremely diiilcult. Three important properties are'high resistance to corrosion from the exhaust gases produced by modern fuels, high resistance to deformation at valve operating temperatures.- and retention of a v high degree of hardness after prolonged exposure to these temperatures.

Poppet valves, and particularly exhaust valves. are siiected to rapidly fluctuating stresses of great intensity while heated to elevated tempera.-

ture by the gases resulting from the combustion Valves which are formed of steels having insufficient hot strength are subject, under these conditions, to gradual deformation. The

vheads are forced downwardly into the seat openings until they become concave or dished which changes the seat angle of the valve, prevents its closing tightly, and thus causes leakage, overheating eventually, failure. I

In order -iinaliy ivo-determine whether any steel will make a satisfactory valve the ultimate test,

A of course, requires that valves shall be made from the steel and run for prolonged periods in'anintornai combustion engine. The manufacturing and testing of valves in this way is a long and expensive procedure, and hence it is highly desirable to devise some preliminary test to which samples of steel can be easily Put for the plll'DO-Sev of determining whether suchsteels warrant the expense of making and running .valves made therefrom. The valve steel problem heretofore has been largely a cut and try problem. and therefore progress in developing new and better valve steels has been much slower than the extensively developed artot alloy steels would seem to warrant.' -It is well recognized however by the comparatively few workers in this highly specialized nary 'short-time.. hot-tensile tests, are not. ipso facto, 'suitable for internal combustion engine Accelerated tests which fairly indicate the Drohable corrosion resistance, in actual operation, of a valve made from steel of a given analysis were devised a few years ago but there has been nov v which hang below the furnace. At any given temperature a load can 'be chosen by successive trials so as to cause the strip to bend or deiiect a-predetermined amount in a specified time. Byv

making, treating and testing all specimens exactly alike the relative resistaices of the steels to the type of head deformation met in exhaust valves can be accurately determined, and, if the specimens are subjected .to the test loads for 24 hours at 1400 F., this newmtesting method has been found to g'ive a g0od`indication of the relative resistances of' steels to deformation in service, as determined by actual engine tests. Comparative .experiments established that the usual,v shorttime. not tensile test gives extremely unreliable indications as to the true value oi' steels for valve service. Many steels shown to be very strong by. such tests but very weak by our accelerated creep" test failed in actual engine tests.

In our tests. all specimens were rated accord-l ing to the load in pounds required to cause a permanent bend or deection of 0.020" therein when applied for 24 hours, and the numbers used hereinafter te indicate the resistance of the various steels to hot bending are to be understood as indicating'such load in pounds. Thus we 11nd that very weak steels may have ratings of less than 5.

Most of the commercial ferritic valve steels will field of research that alloys which are' highly resistant to hot oxidation and have high strength at elevated temperatures, as measured b y ordirange from l0 to 15, and the best commercial austenitic valve steels will range from 20 to 30.

No steels which we have subjected to thisftest have shown values much over 40. l

The alloy steel from which our poppet, valves are made contains the following essential alloylng elements within the ranges stated; it being. understood that the percentages used throughout Tnx.: I

Eject of varying chromium content Tltmdltlftqh l lc ma. Muses. simu All'specimens werehot'worked from 17 lbs. ingots into strips and air-cooled after 30 minutes at 2000` F. The spedmens were tested for Rockwell C hardness and magnetic saturation at 400 LOD-8.50 5 oersteds iield strength,l thenheated-at 1600* F for l hour. air-cooled, reheated at 1400 1" for lhour. and retested. They `were then subjected A .v to the lli-hour "accelerated creep" or hot bend '5.004150 test and the hardness and magnetism again de- Balance 10 termined.

mmm u simoolsd Here is apparent the combination o! strength the specincation and claims reier to byweight.

Per cent 0.25-1L0-0 Carbon Manganese Chromium ..ls- 18.0 A total of elements selected from the group consisting o! manganese and nickel j' Iron Within these ranges the steel is wholly. or

nearly non-magnetic as rolled. or as quenched' 30 and hardness developed with chromium contents from about 2.000 PL, but will become somewhat up to 20% with an abrupt drppln retained hardmsgnetic afterreheating for more or vless proness and strength with chromium contents of longed periods at temperatures of 1200 to 1400v 22%- orV more; The masnetic'data indicate that l'. Inpther words, the steel is neither wholly' in the 24 and 26% chrome alloys soins of the austenitic n or wholly ierritic but betweenvthese 35 so-called "sigma phase is developing as the extremcs.

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numana steels become less magnetic after reheating at the met WW1 Efe'ct of version' monash content in a 20%` @f Mn We are aware that the prior art discloses a great show that inthe absence of so nickel. the desired combination of strensth and retainedhardness isattainsdonlyinaverylimited. upper portionoi our 'total desired range: (4 to 8.5% Mn) The following tab1eshows,however,thatthe formed into pppet valves of internal combustion 05 addition of nickel man! m51. g, mwen mi. and more practical range oimanganese, which is veryrimportant from a manufacturing stand- Ma'nganese and nickel are essentially complementary in our alloy; that is, when'ths IMI-181- nese content is high, the nickel should be low, and vice versa. As the v approaches its upper limit, the nickel may be omitted alto- 4 'I5 -gethen deal ot information about steels whose principal ingredients are chromium and manganess'but no one, so far as we are aware, has discovered the valuable characteristics d by vsteels these elements within the ex` tremely narrow ranges -above set forth. when eneines; v the development oi our-steel 'a large number otexp'erlmental analyses was studied for the purposeo! determining the particular' ranges within j which-the various'elements should be employed in lo order to attain the desired results and for the purpose of determining the enect of lvariations oi' l the elements lwithin these Tanzes. The results .oi'oin'testsoianumberofthesesteelsaretab- "ulated below.

Tseu: III

Eect of 2% nickel in steels similar to in those Table II [m/z, (1r-.0.5% c. 6.3% si, varying Mn) v Treatment (A) Treatment (n) Treatment (e) Rehm; Heat resistance Cr Mn Ni No. to hot Rock- Mag. Rock- Mag. Rock- Mag.

well sat. well sat. well sat. bending 'P-M.- I). 0 1. 0 2. 1 35 7b() 39 13, N0 3Q 1B, 400 i3 t P-l.. 19. 7 4.1 2. 0 33 500 30 l0, 850 37 12, 100 19' P478.. 19. 8 6. 0 2. 1 32 100 38 4, 400 39 7, 800 32 P-l79.. 19. 9 B. 9 2. l 30 50 33 l, 0m 35 4, 400 lll P-180.. 19.7- 6,'1 2.1 31 50 30 m0 27 150 32 P-ml.. 31.0 7. 7 2. 0 29 50 29 1w 28 150 30 P-u.. Il. 1 9. 9 2. l I 29 0 29 60 27 100 32 Tur.: IV

corrosion by hot combustion products which characterizes our steels. The maintenance of this lull contact area permits maximum flowof heat from the valve into the block or head, thus keeping the valve moderately cool and reducing corrosion to a minimum. Under the same conditions s. weaker valve might deform by dish- Eect o! adding nickel to a I% chromium-6% manganese alloy [0.5% carbon, 0.3% silicon] i There is, evidently, no advantage in nickel contents which are higher than those needed to give the best strength, magnetic and hardness properties; but it will be noted that 1% nickel has made a great and valuable change in the character of the 6% manganese alloy. This steel appears to behave exactly like those containing 5% manganese and 2% nickel or the plain 8% manganese steels. In other words, small quantities of nickel when combined with manganese appear to be the equivalent of additional manganese in producing a steel having our desired properties.

The foregoing data reveal conclusively that there exists a narrow composition range within whichsteels may be made which are uniquely qualified to withstand the punishment borne by the exhaust valves of modern internal combustion engines. These steels develop a degree of hardness which is moderate but sufficient to withstand the wearing action on the valve stem and tip, and, moreover, this hardness -is retained after heating to valve operating temperatures so that the seat portion of the head remains suillciently hard to resist the indenting action of hard particles which may be trapped between the valve head and its seat. Our steels are strong at valve operating temperatures and will withstand the stresses developed in operation. Thus, the original contact area between the valve head and seat in the cool engine block or head ol the motor is maintained. This last mentioned feature is an important factor in the superior resistance to ing" down through the valve port, thus' changing the seat angle and reducing the contact area. In such a case the valve overheats to such a degree that even the most corrosion-resistant materials fail.

Many investigators, heating chromium-manganese steels in air or oxygen, have found that they are more heavily scaled than chrome-nickel or plain chromium steels and have therefore conl cluded that they were unsuited for service at elevatedtemperatures.

modern internal combustion engine valves is prin- However, the corrosion of cipally due not, to oxygen but to the products resulting from the combustion of fuels. These products form a deposit on the valves which attacks the hot metal. Many tests have demonstrated that chromium-manganese steels, either with or without small quantities of nickel, are very resistant to such attack when the chromium content is notl much below 20%. We have, therefore, xed the lower chromium content of our alloy at about 18% because of the desirability of maintaining high resistance to such combustion' products. 'The upper chromium limit, however, is sharply defined by the abrupt decrease in strength and hardness of those steels containing chromium in quantities above about 22%, as illustrated in Table I. v

Steels with less than 4% manganese are soft, weak and predominantly ferritic, as shown in Tables II and III, while manganese in quantities above about 8.5% reduces the hardness and not increase the strength. i

The-maximumJ nickel content is not critical but is preferably not over 4%. As discussed in connection with Tables lII and IV, a small quantity of nickel serves to eiiect a more than equal reduction in the manganese content, but too much nickel reduces the hardness to an undesirable degree. essentially a chrome-manganese steel containing not less than 4% manganese with an optimum of from about 7% to 8.5% of this element. However, with manganese contents of less than this optimum, nickel, because oi' its greater eieetiveness, weight for weight, in developing the desirable characteristic o1' our alloy, should alsobe used so that the total manganese plus nickel content is not less than about The following table gives some indication o! does I Thus, it may be said that our steel is manganese and nickel, and the balance iron; the total quantity oi manganese in said steel being 'not less than 4% and not more than 8.5%.

2. An internal combustion engine `valve formed of a readily i'orgeabie alloy steel characterized by vance iron; the total quantityroi' manganese in said steel being not less than 4% and not more than 8.5

3. .An internal combustion engine valve formed the e'ect of carbon: 20' of an alloy steel characterized by being essentially y Tseu: V

Effect of varying carbon in Caf- 6% Mns-2% Ni allows l 'r t t a, v Treatment (A), volgend) Tmmz' #.o'h. iw DE (n) EL 1,400" mauve Hmm. c or Mn N1 1, 5 --Ff @gow nk-M.R0k-M Rock-M. wogll sa? well :4::g well wat?v .es 20.3 0.0 2.0 `2s v1.000 24 0.000 -a 3,000 s. .s4 10.0 n.0 zo a0 s0 as 1,000 laus 4,400 s1 .1.14 20.3 00 2.0I 31 V100 42 1.700 44 0,400 i0 v The minimum carbon content is obviously fixed by the comparative softness of the low-carbon steels while the upper limit is indicated byV The tabulated 'data reveal that steels contain- A ing the essential elements of our invention in the optimum proportions are essentially nonmagnetic as rolled or as rapidly cooled from 2000'l F. but that they become at least moderately magnetic after prolonged reheating `at about 1400*' F., which constitutes one of the distinguishing features of our steel.

The word valve as used in the foregoing description and in the appended claims is to be understood as including in its meaning seat inserts for valves and other parts'associated with valves and inserts which are subjected in use to contact with-the exhaust. gases of an internal combustion engine.

What we claim is:

l. An internal combustion engine valve,v formed of alloy steel characterized by being essentially non-magnetic as rolled, or when quenched from about 2000** F., butwhich becomesv moderately magnetic after reheating at 1200", to 1400 F., in which condition it is highly resistant to deformation at elevated temperatures and retains high hardness after log heating at temperatures up to 1400a F.; said steel containing a plurality of elements of which the following within the ranges stated are then only elements necessary to attain said characteristics: from 0.25% to 1.0% of carbon. from 18% to 22% of chromium, from 5% to 8.5%v selected from the group consisting of 6% to 8.5% selected from the group consisting ci manganese and nickel, and the balance iron; the

total quantity of manganese in said steel being not less than 5% and not more than 8.5%.

4 4. An internal combustion engine valve formed of an alloy steel characterized by being essentially non-magnetic as rolled, or'when quenched from about 2000 F., but which becomes moderately magnet-ic after reheating at 1200 to 1400 F., in which condition it is highly resistant to deformation at elevated temperatures andretains high hardness after long heating at temperatures up to 1400" F.; said steel containing a plurality of elements of which the following within the ranges stated are the only elements necessary to attain said characteristics: carbon .0.40% to 0.70%. chromium 18% to 22%, manganese 7.5% to 8.5%, and the balanceiron.

5. An internal combustion engine valve formed of an-alloy steel characterized by being'essen-4 deformation at elevated temperatures and retains high hardness after long heating at temperatures up to 1400u F.; said steel containing a CERTIFIGATE oF coRREcTIoN.

Patent No. 2.530.821.

WALTER R. BREELER,E1.1 AL;

mation at elevated temperatures and retains high hardness after long heating at temperatures up to 1400 F.; said steel containing a plurality of elements of which the following within the ranges stated are the only elements necessary to attain said characteristics: from 0.40% to 1.0% of carbon, from 18% to 22% of chromium, from 5% to 8.5% selected from the groupv consisting of manganese and nickel, and the balance iron; the total quantityof manganese in said steel lbeing not less than 4% and not more than 8.5%.

WALTER R. BREELER.. GURDON M. BUTLER, JR.

It is herebycertified `that'. .error appears in the printed specification of the above numbered patent requiring Icorrection as fo11cws:'Page 5, Table opposite i page. h., Table V, seventh column thereof', -in the heading,

"P-180",l for the numeral fer "Treatment (A) before teem", reed --Treement (B) before wenn; line line 72, 'same claim, for "then' lread --the--j and that the said letters Patent should be read with this correction therein`that the same may conform. to the record of the case in the Patent Office signed'end eeelear eine 29th dey ef Jennery', A. n. 19M.

Seel) Leslie Frazer F11-et VAssistentcemmieeienexor Patente.

CERTIFIGATE oF coRREcTIoN.

Patent No. 2.530.821.

WALTER R. BREELER,E1.1 AL;

WALTER R. BREELER.. GURDON M. BUTLER, JR.

Seel) Leslie Frazer F11-et VAssistentcemmieeienexor Patente.