US2077117A

US2077117A - Ferrous alloy and process of producing ferrous alloy

Info

Publication number: US2077117A
Application number: US757290A
Authority: US
Inventors: Carl F Lauenstein
Original assignee: Link Belt Co
Current assignee: Link Belt Co
Priority date: 1933-04-07
Filing date: 1934-12-13
Publication date: 1937-04-13
Anticipated expiration: 1954-04-13

Description

April 13, 1937. I c. F. ILAUENSTEIN 2,077,117

* FERROUS ALLOY AND PROCESS OF PRODUCING FERROUS ALLOY Original Filed April 7, 1933 [five 727507" CZU'Z Z laden 566272 25 er than ordinary mai .55 put through any suitable malleabl Patented Apr. 13, 1937 I C E FERROUS ALLOY AND PROCESS OF PRO- DUCING FERROUS ALLOY Carl F. Lauenstein, Indianapolis, Ind., assignor to Link-Belt Company, Chicago, 11]., a corporation 01' Illinois Original application April 7, 1933, Serial No. 664,902. Divided and this application December 13, 1934, Serial No. 757,290

This application is a division of my co-pending After the malleableizing process is completed application Serial Number 664,902, filed April 7. a subsequent heat treatment is applied to the 1933, which is itself a continuation in part of my metal. This heating will usually be done in furapplication Serial Number 475,829, filed August 6, naces, but may, of course, be done by any other 1930. means. The iron is raised to a temperature be- This invention relates to a ferrous alloy and to tween 1375 F. and 1500 F. This temperature isthe process of producing it. The raw material given as approximating the best temperature, but from which the metal is produced is essentially a variation either above or below this tempermalleableized cast iron which contains certain ature is possible. ,After the material has reached 10 strengthening alloying elements. Among those the critical or carbon combining temperature a which may be used are nickel, molybdenum and part of the carbon is combined with ferrite. The copper, manganese, chromium, vanadium and length of time that the material being treated must "aluminum. These may be used in varying be held at this temperature varies with the size amounts. of the parts being treated and with the physical Asgenerally understood, ordinary malleableized properties desired. After the heating has been cast iron is granular in its structure, being comcarried on a sufficient time, the parts are then posed mainly of grains of ferrite and small parquenched, that is to say, cooled, in air, oil, water ticles of carbon or graphitic carbon. One step or other medium. In ordinary practice, no parin the present method or process is designed to ticular effort is made to cool the metal slowly and cause a combination of the carbon and the ferrite where it is quenched in oil or a liquid, it is usually in order to form pearlite or iron carbide.

Another object is to produce a metaland a process for making it in which the metal is stronger than ordinary malieableized cast iron and strongleableized cast iron aiter it has been treated by my heating process. The presence of the alloying elements in the metal improves thephysical properties, particularly improving the ultimate strength, the yield point and the elongation.

Other objects will a the specification and The metal of the present invention is formed from white cast iron. Before the commencement 5 of my process the iron is put through any standcooled rapidly. Where it is metal a tough and wear resisting outer coat, the

heating operation will be-carried out in the presence of a carburizing agent.

When the material being treated has been first heated and quenched, it is thereafter reheated to a temperature not exceeding the critical or carbon combining temperature. The result of this second heating is to cause the martensite or troostite retained after the first heating to break down into pearlite or sorbite. This change will normally be effected at a temperature range of 900 F. to 1350 F. The cooling, after the second heating, is preferably air cooling although a water or oil quenching may be used, depending somedesired to give the ppear from time to time in claims.

ard or suitable malleableizing process. White cast What upon the: physical properties desired. A iron has an average chemical composition as folwater quenching .produces a stiffer, higher lows: strength iron, while oil and air cooling produces Percent relatively more ductile, iron. Any cooling method Combined carbon 2.30-2.40 may be i Graphitic carbon Nil The accompanying drawing illustrates in Figure Silicon v .90- .95 1 the structural arrangement and constituents of Manganese 2' a sample of malleableized cast iron and in Figure Sulphur 2 a sample of the metal of my invention. The Phosp figures are diagrammatic showings based upon microphotographs of samples of metals. They To this may be added suitable quantities of suggest diagrammatically only typical forms of copper, molybdenum, nickel, manganese, chromlum vanadiu n aluminum or'other alloying 1 the metal. Other samples would show the same t Th alloying elements may be added general characteristics, but would show detailed into the cast iron in thefurnace or the ladle, or modlficaiions- In Figure 1 the metal granular. It is composed ferrite and separated fr boundaries B. The grain shapes and sizes.

at any time before the iron is finally molded. The white cast iron with the alloying elements is poured into suitable molds and allowed to cool. It may then be cleaned and after cleaning it is eizing process.

is seen to be generally of grains, A, which are om each other along s may be of irregular Interspersed through the mass of the metal are spots of free or graphitic carbon C.

Figure 2 is a diagram based upon a microphotograph of a section of a sample of the metal of this invention. g

As illustrate in the drawing, the metal is generally granular, being formed of grains. A. These grains are bounded or separated along boundaries B. The grains are in the form of ferrite. C represents a spot of graphitic or free carbon. In a larger sample of the metal a number of such spots of graphitic carbon would appear. Situated throughout the metal, surrounding the grainsand the graphitic carbon and filling the great majority of the grain boundaries and to some degree penetrating within the ferrite grains themselves is pearlite. This material is indicated at D.

Figure 2 illustrates an important characteristic of the present invention, namely that there is distributed throughout the metal, along the grain boundaries and about such particles of graphitic carbon as are present, an agent which tends to stiffen the grains and prevent'their distortion under stress, thus strengthening the mass and preventing the separation or pulling apart of the grains. This agent is an iron carbide with alloy content and in the form illustrated in Figure 2, is normally pearlite or sorbite. It is characteristic of this iron carbide, which in this case may be. pearlite or sorbite, that it is strong and tough and it thus strengthens the grains against distortion, holding the grains together more strongly than in other cast iron where the ferriteis combined without the presence of any appreciable amounts of alloy pearlite at the grain boundaries. It thus increases the tensile properties of the material.

It also makes the metal of the invention highly resistantto wear or abrasion. The harder and tougher alloy pearlite or alloy sorbite at the ferrite grain boundaries acts as a guard preventing the-wearing or abrading away of the softer ferritegrains. The pearlite orsorbite is strengthened by .the alloying elements In the metal of this invention, the main body of the metal is made up' of a group of ferrite grains. The great majority of these grains is surrounded each with a harder shell of pearlite or sorbite, that is to say, with a shell of an iron carbide with alloy content which has such physical properties that it tends to strengthen the grains of ferrite. It prevents deformation of the grain and by this fact it resists distortion of the grain and resists breaking of the grain itself or separation of one grain from the other. This iron carbide in the body of the metal may be said to act like an iron reinforcement about a piece of wood. It prevents distortion and so prevents splitting and breaking. Thus in the metal of this invention there is built up throughout the body of the metal a reinforcing framework of the stronger iron carbide which has many cell-like compartments in it. These cells surround the weaker grains of the ferrite which are thus strengthened and the separation of these grains of ferrite is resisted by this cell likestructure of the carbide. In effect there is built up a structure which may be likened to a honey comb. This is formed of the iron carbide and within the cells of the honey comb are found the grains of ferrite. The honey comb thus serves to strengthen the individual grains and to resist deformation of them and further, to resist deformation of the mass as a whole and ,to prevent separation of the grains.

As above indicated, the metal owes its strength to the presence of the pearlite or iron carbide network surrounding the grains and lying within and along the grain boundaries. The presence of the i alloying metal gives thisnetwork ahigher strength and hardness than that which it would otherwise have if the alloying element were not present.

The temperature ranges above suggested are not absolute limits and are indicated for the first heating as being within the range of the critical or carbon combining temperature, and for the second heating as being above the range of customary hot galvanizing. In the first heating the temperature may be as high as 1500 F. and in the second heating it may be as low as 900 F., although in normal practice the first heating is preferably between 1425" F. and 1450". F. and the second heating is preferably between 1200 F. and 1250 F. K

The increasedstrength of my metal resultant from the use of the alloying element is possibly caused by the pearlite or sorbite, including such an alloy content, having higher physical proper- 'the resultant properties of my metal can also be so varied.

The alloying materials above mentioned are only given as typical metals for this use. Many others might be used. For some purposes one will be used alone and for other purposes two or more will be used together. Thus one alloy might include 1.50% nickel only. Other alloys might include .30% copper and .30% molybdenum andjstill other alloys might include .30%

molybdenum and 1.50% nickel. Thus a very wide variety of alloying elements and combina-' tions of these elements maybe used in my invention. k

In general, the typical alloying elements and the quantities of them which are most likely'to be used are as follows:

Percent Copper .35 to 1.00 Manganese .50 to 1.00 Molybdenum .20 to .60 Nickel .50 to 1.50 Chromium .10 to .60 Vanadium .10 to .60 Aluminum .10 to 1.00

Where in the claims I have used the expression an alloying element of the carbide forming group of elements consisting of manganese, molybdenum, chromium and vanadium, and the further expression an alloying element of the ferrite alloying group of elements, consisting of nickel, copper and aluminum, I mean any one or more of the elements above mentioned, that is to say, molybdenum, nickel, copper, manganese, vanadium, chromium and aluminum, used substantially within the limits above stated. These alloys may be used singly, generally within the ranges indicated, or in any combination of two or more of them.

Percent Combined carbon 2.40 Graphitic carbon Nil Silicon .95 Manganese .27 Sulphur .060 Phosphorus .16 Nickel 1.50 Molybdenum .30

After annealing or malleableizing treatment- Combined carbon .0 Graphitic carbon 1.80 Silicon .90 Manganese .27 Sulphur .060 Phosphorus .16 Nickel 1.50 Molybdenum .30

After final heat treatment the analysis is: Combined carbon .40 Graphitic carbon 1.40 Silicon .90 Manganese .27 Sulphur .060

When the alloying metals are used the annealing or malleableizlng cycle is generally the same as that typical of the manufacture of malleable iron. In some cases the alloy content may necessitate slight variations from the standard. One typical annealing cycle may be as follows: Heat the metal to 1650 F.. this heating occupying about 36 hours; hold the metal at 1650 F. for 36 hours. Cool to 1200 F. at 6 F. per hour, occupying about 72 hours. The furnace may then be unloaded and after cooling and inspection the castings or other -metal articles may be put through the secondary heat treating cycle. A typical heat treatment for metal of about .30% copper and 30% molybdenum content would be: Heat to 1475 F.; quench in oil; reheat to 1200 F. and quench in water. If the metal were an alloy including 1.00 nickel and .30% molybdenum, the first heating would be carried out to a temperature between 1400 F. and 1450 F. and the second,

heating would be carried out to a temperature between 1200 F. and 1250 F., and instead of the final quenching in water, the articles might be cooled by air. Other changes in temperatures and times of heating may be desirable or may be necessary where other alloying metals are used or where they are used in different proportions. Generally where nickel, copper or aluminum are used as alloying agents the first treating temperature of the heat treatment will, as a rule, be lower than 1475 F. and it may be lowered to 1400 F., due to the depressing effect that these elements have on the critical temperature. Some of the other elements listed do not have such a marked effect on the critical temperature but in general tend to raise it slightly.

It is therefore possible to use such an alloy as nickel, which depresses the critical temperature, and add to it molybdenum, which has a. slightly opposite or cancelling effect, and use a first treating temperature of 1450 F. In any event, the treating temperatures must be governed by the alloying elements and the desired physical properties in the finished part.

The following analyses are given as typical of one alloy combination of metal produced by the method of this invention:

Before annealing or malleableizing treatment- Phosphorus .16 Nickel 1.50 Molybdenum .30

The analyses given are typical of only one of a large number of possible combinations and the invention is not in any way limited to the analyses given.

Other alloys which have proved satisfactory and which include a metal of the ferrite alloying group and the carbide forming group, include the following proportions of copper and molybdenum:

Copper molybdenum- 30% Cu.-.30% Mo.

.80% Cu..30% Mo. 1.20% Cu..10% Mo.

With this alloy in the proportions indicated, it is preferable to reduce the first heating so that it is carried out to a temperature of from 1425" F. to 1475 F.

Another alloy including metal of each group is nickel, 1.00 per cent, molybdenum .30 per cent.

In this alloy the first heating is preferably in the neighborhood of 1425 F. and the second heating is higher than in the general practice above suggested, namely, 1325 F.

The alloys and temperatures above indicated are merely illustrative of the fact that a wide molybdenum, chromium and vanadium, in ap-.

proximately the following proportions: Manganese .50 to 1.0 per cent; molybdenum .20 to .60 per cent; chromium .10 to .60 per cent and vanadium .10 to .60 per cent, together with at least one {element of the ferrite alloying group of elements,

consisting of nickel, copper and aluminum in proportions up to 1.50 per cent, and including ferrite, graphitic carbon and iron carbide, the latter being distributed along the grain boundaries and between the grain of .ferrite and about the graphitic carbon.

2. A granular ferrous metal including an alloying element comprising: manganese .50 per cent to 1.00 per cent, and a second alloying element comprising: nickel .50 to 1.50 per cent, and including ferrite, graphitic carbon and iron carbide, the latter being distributed along the grain boundaries and between the grains of ferrite and about the graphitic carbon.

3. A granular ferrous metal including an alloying element comprising: molybdenum .20 per cent to .60 per cent, anda second alloying -element, nickel .50 to 1.50 per cent, and including ferrite, graphitic carbon and iron carbide, the lat-,

ter being distributed along the grain boundaries and between the grains of ferrite and about the graphitic carbon.

4. A granular ferrous metal including an .al-- loying element comprising: molybdenum .30 per cent, and a second alloying element comprising: nickel 1.00 per cent, and including ferrite, graphitic carbon and iron carbide, the latter being distributed along the grain boundaries and be-, 5

tween the grains of ferrite and about the graphitic carbon.

5. A granular ferrous metal, including at least one alloying element of the carbide formin group of elements consisting of manganese,

- .50 to 1.50 per cent; copper .35 to 1.00 per cent and aluminum .10 to 1.00 per cent, and including grains of ferrite, graphitic carbon and iron carbide, the latter being distributed along the grain boundaries and between the grains of ferrite and about the graphitic carbon.

6. The process of heat treating malleableized cast iron, which iron includes an alloying element of the carbide forming group of elements consisting of manganese, molybdenum, chromium and vanadium in approximately the following proportions: manganese .50 to 1.0 per cent; molybdenum .20 to .60 per cent; chromium .10 to .60 per cent and vanadium .10 to .60 per cent and including ferrite, together with an element of the ferrite alloying group of elements consisting of nickel, copper and aluminum, in approximately the following proportions: nickel .50 to 1.50 per cent; copper .35 to 1.00 per cent and aluminum .10 to 1.00 per cent, which process includes heating the iron to a point between 1375 F. and 1500 F., quenching and reheating to a point between 900 F. and 1350 F.

CARL F. LAUENSTEIN.