US1660925A - Motor valve and alloy steel therefor - Google Patents

Description

Feb. 28, 1928. 1,660,925

- R. JARDINE I 4 MOTOR VALVE AND ALLOY STEEL THEREFOR Filed Jan. 5. 1922 RabfZ fardme %777695 Patented Feb. 28, 1928.

UNITED STATES 1.950325 PATENT OFFICE. 4

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Application filed January 3, 1922. Serial No. 526,687. I

The invention relates to valves for explosive engines, and specially to poppet valves, wherein the valve head and adjacent portion of the stem are exposed to the high 5 temperature and corrosive-action of the exploded charges and the rim or shoulder of the valve head is subjected to mechanical wear while highly heated. The object of the invention is to provide an improved 1 motor valve designed to resist both corrosive action and, mechanical wear at high temperatures. A further object of the invention is tov provide an alloy steel of novel composition from which the improved valve may be produced.

The accompanying drawing is a side elevation showing a form .of motor valve to which the invention may be applied.

As is well known, motor valves of the form shown, especially exhaust valves, be-

come highly heated in service, particularly in the head 10 and the adjacent portion 11 of the stem 12. These valves are accordingly exposed to the deterioratinginfluence of both mechanical wear and'the corrosive action of the exhaust gases, while in a heated condition. Furthermore, the effect of these two deteriorating influences is mpst pronounced'upon the beveled rim or shoulder 13 of the valve head, where an accurate engagement with the valve seat (not shown) is desired.

It has also been recognized that warping of the valve, whether resulting from a temporary distortion due to unequal heating of different parts of the valve, or, from a permanent distortion arising fr0mrepeated heating and cooling, disadvantageously af-f fects the fit of the beveled shoulder 13 upon its seat. In this connection it is understood that warping does not occur to a noticeable degree from either of these causes, if the temperatures attained are not higher than they decalescent point of the steel from which the valve is made. .It follows that,

objectionable warping is substantially avoided by forming the valve of a steel having a decalescent point which isabove that likely to be attalned in any partof the valve inservice.

The present invention 'accordinigly contemplates a valve WhlCh is forme rom a special alloy steel, the same-being prefer-- a ly used for the rim portion 13 of the valve head 10, either with or without the forma- Tungsten *4 2.00

Manganese tion ofany part or all of the remainder of the valve from the same material. For, this purpose the said special alloy steel should have-as its important characteristics, so-called red hardness, a decalescent point above the highest temperature likely to be attained in any part of the valve in service, and resistance to corrosion at high temperatures as well as in the cold state, to a marked degree. Such an alloy steel should preferably contain chromium or chromium and silicon together, or its or their equivalents, in sufficient quantity to im art the desired resistance to corrosion. ikewise the said special alloy steel should contain tungsten or tungsten and molybdenum together, or its or their equivalents, in sufficient quantity to impart the desired red hardness property.

Examples of the alloy steels-which may be used are as follows, the first being preferably employed for high grade valves adapted for use in so-called high-speed motors where high temperatures are attained and other service conditions are severe, although it has been foundthat the second analysis indicated below gives excellent results.

Alloy steel No. 1

Alloy steel N0. 2

Carbon .50 Chromium.- 6.75

Per cent. a .1. 20

Molybdenumuu; 80 Silicon 2. 00

40 Sulphur .035 max. Phosphorus .005 max.

The foregoing examples are merely illustrative and are not-intended to indicate the 105 maximum and minimum amounts of the various constituents within the scope of the invention. For example, there is no reason to believe that resistance to corrosion would become less if more than fifteen per cent of 11 0 chromium were used, and possibly a red hardness suflioient for some purposes would resultfrom the use of less than two per cent of tungsten and eight-tenths of one per cent of molybdenum. On the other hand, While it is believed that an increased amount of chromium may be used Without high silicon anda larger amount of tungsten used without molybdenum, it is understood that high silicon Will not impart the desired resistance to corrosion unless a substantial amount of chromium is also used. Furthermore, molybdenum is desirably used for the reason that in the presence of tungsten it increases the red hardness property to a greater extent than an equal additional amount of tungsten,

and it also avoids Waste by reducing the tendency to piping and the like. Any of the elements, usually regarded as scavaging or purifying elements, suph as aluminum, titanium, uranium, vanadmm and zirconium,

may be used in addition to manganese, if

desired 1 claim as my invention An alloy containing the following:

Remainder principally iron.

ROBERT JARDINE.

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