US2691576A - Wear-resistant cast iron for cylinder liners and the like - Google Patents

Description

Oct. 12, 1954 F. J. WEBBERE 2,691,576

WEAR-RESISTANT CAST IRON FOR CYLINDER LINERS AND THE LIKE Filed May 15, 1952 l nve ntor By flea 4272-152 W '2 Attorneys Patented Oct. 12, 1954 WEAR-RESISTANT CAST IRON FOR CYLIN- DER LINERS AND THE LIKE Fred 'Jr Webbere, Royal Oak, Mich., assignor. to

General Motors Cor corporation of Delaware poration, Detroit, .Mich'., a

Application May' 1'5, 1952,.Serial No. 288,008

6 Glaims. (01. 75-128) This invention relates to a highly wear resist ant cast iron and particularly to such. a cast iron which is especially adapted for partssuch as cylinder liners of an internal combustion engine.

As is well known in the art, the wear resistance of cast iron is substantially improved by small amounts of phosphorus and titanium; United States Patents Nos. 2,179,695 and; 2,225,997, which issued November 4, 1939 and November 24, 1940; respectively, in the name of Walter. E. Jominy disclose examples of this type of cast: iron. Heretofore, however, the use of titaniumlcast iron has been limited by'the difficultyencountered in introducing the titanium into the: melt because of'the aifinity of titanium f'or oxygen and nitrogen, Large quantities of slagare formed, and' a high percentage of titanium is lost as the. result of this afiinity.

Prior to the present invention these alloying A components were generally added separately in the form of ferro-titanium, silicon-titanium, or ferro-phosphorus alloys. Inasmuch as these alloys are relatively high'melting point combinations of elements, they must be subjected toza high temperature for a. considerable amount of time in order to place them in solution. Hence these hardening alloys necessarily areaddedudirectly' to the furnace. Such a procedure usually results in a titanium recovery, for example, of approximately only 50%. On the other hand, when .the above elements are combined in certain relatively low-melting intermediate alloys and added to the ladle; almost 100% of the titanium may be recovered because the phosphorus present in the intermediate alloy permits a rapid rate of solution which effectively precludes oxidation of the titanium.

It is therefore a principal object of my inven tion to provide a cast iron whose wear resistance has been greatly increased by the presence: of nickel, titanium and phosphorus. A- further object of the invention is to provide a cylinder liner formed of such a cast iron having outstanding anti-score and wear resistance properties.

The cast iron formed in accordance with my invention not only possesses the resistance to scoring characteristic: of cast iron, but. also excellent properties of wear resistance under severe operating conditions. This cast iron is especially adapted for such parts as piston rings, pistons, valves, valve guides, tappets, bearingsand other parts ordinarily subjected to wear. More particularly, I have found that my alloy may be used to form cylinder liners which have outstanding 2. wear resistance properties and are superior in this respect to those heretofore used.

The above and other objects are attained in accordance with my invention by cast iron containing minor proportions of carbon, silicon, manganese', chromium, nickel, titanium. and phos phorus and a major proportion of iron plus the usual incidental impurities; A preferred method of forming my cast iron employs a single inter-'- mediate alloy containingtitanium, nickel and phosphorus which is added to the ladle immediately prior to pouring the molten cast iron. The presence of" nickel and" titanium, together with phosphorus, in my intermediate alloy improves'the wear resistance of the resultant cast iron-by beneficially modifying the phosphorus eutectic. More specifically, I have found that titanium losses into the slag may: be greatly reduced and the wear resistance of the cast iron accordingly'increased ifan intermediate ferrous base'alloy containing nickel, titanium and phos-' phorus is added to the molten" cast iron inthe ladle immediately prior to casting. Thisladle addition is possible because of the relatively low melting point of the alloydueto the percentage of phosphorus present.-

Other obj'ectsand advantages of: my invention will more fully appear from the following'detailed descriptionv of a preferred: embodiment of my inventiontaken in conjunction with the aceompan'ying drawing which shows acylinder liner for an internal combustion engineformed. of a cast iron: in accordance with my invention.

Referring more particularly tothe drawing, there is shown. a cylinder liner for an internal combustion engineformed" of a cast iron in which the wear resistance is substantiallyincreased'by the presence of a hard network: of atitaniumcontaining phosphorus eutectic. Regardless of the exact chemical composition of this hard phase, its presence is' primarily responsiblefor the further increasev in wear resistance. Hence the present invention. provides a cast iron having physical characteristicswhichsatisfy all requirements? of cylinder liners and other related bearing. parts.

Wear'resistance, of course, is afunction of both the size. and distribution of the aforementioned hard network. Inasmuch as the size and distribution of the network are. dependent on such factors as the metal viscosity, solidification rate and method'of alloying, the preferred procedure for preparing my cast ironprovides maximum wear resistance with minimum attrition. Thus I have'found that superior results are obtained by introducing the phosphorus, nickel and titanium in the form of a solid phosphorus nickel-titanium-iron intermediate alloy hardener.

An intermediate alloy which I have found to be highly satisfactory is one comprising 3.5% to 18% titanium, 6% to 13% nickel, 15% to 35% phosphorus and the balance substantially all iron. In order to obtain optimum results, however, I have found that the titanium content of the intermediate alloy should be maintained within the preferred range of 6% to 13% by weight of the intermediate alloy.

A highly wear-resistant cast iron is produced when such an alloy is introduced as a ladle addition to a ferrous base metal which contains between 2.5% to 4% carbon, 1.5% to 3% silicon, 0.5% to 1% manganese, and 0.1% to 1% chromium. This cast iron may also initially contain small quantities of nickel and phosphorus, these elements frequently being present in amounts in the order of 0.05% to 0.1% and 0.05% to 0.25%. respectively. The intermediate alloy is preferably added in an amount sufficient to permit the aforementioned 3.5% to 18% titanium content to constitute between 0.05% and 0.35% of the final casting alloy. Hence a 1% to 2% alloy addition has proved effective to acomplish this result.

Inasmuch as the quantity of the intermediate alloy employed is very small as compared with the amount of cast iron to which it is added, the percentages of the alloying constituents originally present in the cast iron remain substantially unaltered in the final alloy. Hence a cast iron comprising approximately 2.5% to 4% carbon, 1.5% to 3% silicon, 0.5% to 1% manganese, 0.1% to 1% chromifim, 0.1% to 0.45% nickel, 0.05% to 0.35% titanium, 0.3% to 0.7 phosphorus and the balance substantially all iron possesses a very high degree of wear resistance. As hereinbefore stated, excellent results are obtained with an intermediate alloy having a titanium content between 6% and 13%, and the use of a proper amount of this preferred hardener alloy composition results in a final casting which contains 0.08% to 0.15% titanium.

For particular purposes it may be desirable to include a small amount of vanadium in the cast iron and, if this is done, it should be present in the original ferrous metal melt in an amount between 0.05% to 0.15%. This vanadium content is approximately the same both before and after the hardening alloy addition because of the relatively small amount of the intermediate alloy required. It will be understood, of course, that the cast iron formed may also contain other in cidental impurities, such as sulfur, but for best results the sulfur content should not exceed approximately 0.2%.

As an example of a specific intermediate alloy which may be used in forming my highly wearresistant cast iron, one containing 9.1% titanium, 9.1% nickel, 20.4% phosphorus and the balance iron has proved to be highly satisfactory. This alloy should be added in an amount calculated to yield approximately 0.15% titanium, 0.2% nickel and 0.45% phosphorus in a cast iron containing 3.2% carbon, 2.5% silicon, 0.75% manganese and 0.35% chromium. Approximately 0.1% vanadium may also be included in the cast iron and provides a final casting which has good working characteristics as well as high wear resistance. These properties are particularly desirable in cylinder liners of internal combustion engines, such as the diesel engine cylinder liner i shown in the drawing. This liner is otherwise of rather conventional construction and is provided with the usual scavenging ports l2.

When the above-described intermediate alloy is added to the ladle containing the aforementioned ferrous metal immediately prior to the casting operation, the resultant cast iron has proved to be considerably more wear-resistant than the same ferrous metal to which the intermediate alloy has not been added. As an illustration of the improved physical properties of the former, wear test samples of the abovedescribed cast iron formed in accordance with my invention and cast into sand-resin molds yield an average wear loss between 0.012 grams and 0.016 grams when tested in a standard wear test machine. This wear loss indicates wear resistance superior to that obtained with the same initial cast iron to which a nickel-titanium-phosphorusiron intermediate alloy has not been added. The latter cast iron shows wear losses which are between approximately two and three times as great as those obtained with my improved cast iron. For example, using the same wear testing procedures and equipment indicated above, the cast iron samples containing no titanium, phosphorus or nickel show an average wear loss between 0.035 and 0.06 gram.

Results of the above and other tests on cast iron prepared in accordance with my invention and containing as little as 0.05% titanium indicate that the above-described intermediate alloy imparts to cast iron a wear resistance superior to conventional cast irons which contain considerably more titanium in the final casting. An even greater amount of titanium must be initially added in these latter instances, moreover, because of the low titanium recoveries resulting from the separate addition of the alloying components. Hence, it should be noted that adding nickel, titanium, phosphorus and iron in the form of a single complex alloy not only permits the ladle addition of titanium and thereby substantially increases the percentage of titanium recovered, but also provides my cast iron with a wear resistance superior to that obtained by the separate addition of the alloying ingredients.

The exact alloying procedure to be employed with reference to temperatures used and mechanical steps to be taken may be conventional in nature and, being well known in the art, requires no further explanation. However, inasmuch as it is desirable to dissolve such an intermediate alloy as quickly as possible in the molten cast iron, I find it advantageous to add such an alloy in aform having a high ratio of surface area to volume, such as crushed material having particle diameters of approximately inch or less. It will be understood, of course, that such an intermediate alloy may be added in other forms, but the above procedure facilitates the alloying operation and results in maximum titanium recovery. Any suitable melting furnace may be used; and normal tapping temperatures may be employed, such as those between 2700 F. and 3000 F.

It also will be understood that, although my invention has been described by means of certain specific examples of cast irons characterized by high wear resistance and intermediate alloys for forming such cast irons, the scope of my invention is not to be limited thereby except as defined in the appended claims.

I claim:

1. A highly wear-resistant cast iron consisting essentially of 2.5% to 4% carbon, 1.5 to 3% silicon, 0.5% to 1% manganese, 0.1% to 1% chromium, 0.1% to 0.45% nickel, 0.05% to 0.35% titanium, 0.3% to 0.7 phosphorus, and the balance substantially all iron.

2. A cast iron characterized by a high degree of wear resistance consisting essentially of 2.5% to 4% carbon, 1.5% to 3% silicon, 0.5% to 1% manganese, 0.1% to 1% chromium, 0.1% to 0.45% nickel, 0.08% to 0.15% titanium, 0.3% to 0.7% phosphorus, 0.05% to 0.15% vanadium, sulfur not in excess of 0.2%, and the balance substantially all iron.

3. A cast iron characterized by outstanding anti-score and wear resistance properties, said cast iron consisting essentially of 3.2% carbon, 2.5% silicon, 0.75% manganese, 0.35% chromium, 0.2% nickel, 0.15% titanium, 0.45% phosphorus, and the balance iron plus the usual incidental impurities.

4. A cylinder liner for an internal combustion engine, said liner comprising 2.5% to 4% carbon, 1.5% to 3% silicon, 0.5 to 1% manganese, 0.1% to 1% chromium, 0.1% to 0.45% nickel, 0.05% to 0.35% titanium, 0.3% to 0.7% phosphorus, and the balance iron plus incidental impurities.

5. A highly wear-resistant cylinder liner for an internal combustion engine, said cylinder liner consisting essentially of 2.5% to 4% carbon, 1.5% to 3% silicon, 0.5% to 1% manganese, 0.1% to 1% chromium, 0.1% to 0.45% nickel, 0.08% to 0.15% titanium, 0.3% to 0.7% phosphorus, 0.05% to 0.15% vanadium, sulfur not in excess of 0.20%, and the balance iron plus incidental impurities.

6. In an internal combustion engine, a cylinder liner characterized by excellent anti-score and wear resistance properties consisting essentially of 3.2% carbon, 2.5% silicon, 0.75% manganese, 0.35% chromium, 0.2% nickel, 0.15% titanium, 0.45% phosphorus, and the balance iron plus the usual incidental impurities.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,391,215 Speer Sept. 20, 1921 2,179,695 Jominy Nov. 14, 1939 2,336,001 Eash Dec. 7, 1943 OTHER REFERENCES Alloy Cast Irons Handbook, 2nd edition, page 252, published in 1944 by the American Foundrymens Assn., Chicago, Ill.

Claims (1)

1. A HIGHLY WEAR-RESISTANT CAST IRON CONSISTING ESSENTIALLY OF 2.5% TO 4% CARBON, 1.5 TO 3% SILICEN, 0.5% TO 1% MANAGANESE, 0.1% TO 1% CHROMIUM, 0.1% TO 0.45% NICKEL, 0.05% TO 0.35%

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