US3114033A

US3114033A - Rods for welding cast iron, especially high grade cast iron

Info

Publication number: US3114033A
Application number: US52172A
Authority: US
Inventors: Elster Curt Christian; Hummitzsch Werner
Original assignee: WESTFAELISCHE UNION AG
Current assignee: WESTFAELISCHE UNION AG; WESTFALISCHE UNION AG fur EISEN- und DRAHTINDUSTRIE
Priority date: 1959-09-02
Filing date: 1960-08-26
Publication date: 1963-12-10
Anticipated expiration: 1980-12-10
Also published as: DK103980C; DE1243499B; GB953352A

Description

Dec. 10, 1963 c. c. ELSTE ETAL RODS FOR WE NG CAST 0N, PECIALLY HI GRADE '1 IR Filed Aug. 1960 FIG. I.

FIG. 3.

United States Patent The present invention relates to rods for welding cast iron and, more particularly, to welding rods containing addition material for effecting the welding of cast iron and steels without the necessity of high temperature preheating procedures.

In the customary hot welding of cast iron, addition rods or Welding rods are used to form a connecting seam with the cast iron which possess a similar structure to that of the cast iron being welded. Cast iron prepared by machine casting in accordance with the usual industrial practice has the following typical chemical analysis of alloying materials:

Percent Carbon 3.0-3.5 Silicon 1.5-2.5 ldanganese 0.6-1.2 Phosphorus 0.4-0.6 Sulfur 0.04-0.08

Nevertheless, slight deviations occur in the cast iron prepared as to the content of alloying material noted above. The structure of the cast iron, however, generally comprises graphite, perlite and ferrite. The form in which the graphite is separated will depend upon the smelting procedure, the cooling and the silicon content. The Brinell hardness value of such machine casting material normally ranges Within the HB limits of 140-170 kg./mrn.

In accordance with machine casting procedures of the foregoing type, nickel or chromium may also be present in order to adjust and regulate the degree of toughness and hardness of the cast iron to be produced.

in addition to the foregoing cast iron, refined types of cast iron may be prepared having increased toughness as noted by the usual bending test. Such refined cast irons, however, possess lower phosphide content and contain finely distributed graphite veins. For the most part, the graphite veins are more uniformly distributed throughout the cast iron than is found in cast iron prepared by the normal machine casting techniques.

A further type of cast iron having a basic structure of perlite may be prepared in which the graphite is similarly finely distributed. Such high grade perlite cast irons exhibit high tensile strength of 35 kg/mm. and higher, in consequence of their steel-like basic structure. The chemical composition of such refined perlite cast iron may have the following constituents:

Percent Carbon 2.5-3.0 Silicon 0.6-1.5 Manganese 0.5-0.8 Phosphorus About 0.1 Sulfur About 0.06

In addition, a spheroid cast iron may be provided in which the graphite is formed in spherical shape. Nevertheless, the basic structure is composed of ferrite. The tensile strength of such spheroid cast iron ranges from 50 to kgL/mmP. range between and 270 units. of this ferritic iron is as follows:

The Brinell hardness values may The chemical analysis 3,114,033 Patented Dec. 10, 1963 Percent Carbon 3.0-3.7 Silicon 2.2-2.6 Manganese 0.3-0.5 Nickel About 1.0-1.8 Phosphorus About 0.1 Sulfur About 0.02 Magnesium About 0.07

In welding cast iron parts, hot welding procedures afford the greatest certainty that a desirable connection will be attained. Hot welding may be executed by heating gas or electric current in the conventional manner. For this purpose cast welding rods are normally used which are provided with a casting skin or covering, or even with grooves or recesses filled with a flux material. Cast welding rods conventionally used have the following typical composition:

. Percent Carbon 3.0-3.6 Silicon 2.8-3.8 Manganese 0.5-0.8 Phosphorus At most 0.6 Sulfur Less than 0.1

Carbon, Silicon, Manganese,

percent percent percent Electric arc welding 3. O 2. 6 0. 40 Gas welding 3.1 2. 7 O. 38

The structureof the iron material in this regard consists of graphite, ferrite and perlite.

In the normal casting technique, the cast iron material is preheated to about 600 C. and often to higher temperatures in order to give maximum eifect to the hot welding operation. The iron welding rod which serves as addition material or binding material possesses a considerably higher silicon content than that of the cast iron parts to be welded. Increased silicon content of 2.8 to 3.8% are normally used in order to promote graphite formation upon welding. The weld traverses the interval from the melting temperature to the eutectoid value at 730 C. with respect to the iron-carbon diagram considerably faster than does the cast iron during its solidification in the casting mold. Hence, the increased silicon content is used for accelerating the graphite formation.

it is an object of the present invention to overcome the drawbacks encountered with respect to prior art welding techniques and to provide an efiicient addition material for welding cast iron at lower temperatures than were heretofore believed necessary.

Other and further objects of the invention will become apparent from a study of the within specification and accompanying drawing, in which FIGS. 1-4 illustrate schematic perspective views partially in section of welding rods in accordance with various embodiments of the invention.

in accordance with the present invention, it has been found that present day cast iron may be welded with iron welding materials having compositions which vary with respect to the welding rod compositions customarily used in the past. The addition materials in accordance with the invention may be applied for welding both thick and thin walled cast iron parts advantageously without the requirement of a high temperature preheating step. Accordingly, the inherent stresses in the casting body are favorably accommodated and solid, stable unions are obtained in spite of the omission of a high temperature preheating step.

The welds which may be formed in accordance with the invention may desirably contain in considerable measure ledeburitic structural constituents of white iron. Moreover, the Welds may also consist of a mixed structure of ledeburite, perlite and graphite wherein the portion of graphite is generally below about 1.5%.

According to the Maurer phase diagram (Stahl-l-Eisen 44 (1924), No. 48, pp. 1522-1524, or Kruppsche Monatshefte (1924), pp. 115-122) for cast iron, the above mentioned cast iron welds formed in accordance with the invention vw' ll be found in the range of I, Ha and H at a total carbon content of 1.5 to 2.5%, and a silicon content of 1.0 to 2.5%. The manganese content will range within the limits of 0.3 to 1.2%. As may be appreciated by the artisan, nickel, chromium, aluminum and magnesium may also be added as desired.

Thus, a welding rod containing the addition material in accordance with the invention, upon welding will yield a cast iron weld including a graphite content below about 1.5% and will contain:

Percent Carbon 1.5-2.5 Silicon -l 1.0-2.5 Manganese 0.3-1.2 Phosphorus 0.02-0.2 Sulphur 0.02-0.l

A particularly suitable cast iron weld of the foregoing type found in practice includes a graphite content of 0.2-1.2% and contains the following:

This weld results in a structure which contains ledeburite as well as graphite and penlite. The amount of graphite present will be between 0.2-1.2% in dependence upon the rate of cooling. The Brinell hardness of Welds of this type ranges between the values of 200-350 HB. Nevertheless, these values may be decreased by suitable heat treatment to 170 HB.

The iron welding material which may be used in the form of cast iron welding rods generally contains from 1.5 to 2.8% of carbon and from 0.3 to 1.2% manganese.

Generally, for welding in accordance with the inven tion cast welding rods may be used having approximately the following composition:

Percent Carbon 1.5-2. 8 Silicon 1.5-2.7 Manganese 0.3-1.2

Where gas welding is concerned, the welding rods in accordance with the invention may preferably have approximately the following composition:

As a rule, these rods are welded with the cast iron parts in the presence of a fluxing agent in powder or paste form in the usual manner. Nevertheless, the fluxing agent may pressed for the various ingredients be carried by the rod itself within a groove or recess therealong, or by providing the flux agent as a covering for the rod itself.

As may be seen from FEGS. 1-4, welding rods in acc'ordance with the invention may have a substantially rect'angular or circular cross section. The rod 1 is provided with a recess for retaining the flux agent 2, as shown in FIG. 1 and FIG. 4, or may be provided with a sheath of ilux agent 2 surrounding the inner core rod 1, as in FIG. 2. Alternatively, V grooves may be provided in the rod 1 for carrying the flux agent 2, as shown in FIG. 3.

In the case of electric arc welding, the rods in accord ance with the invention may be formed of the same composition as those used in gas welding procedures. Welding rods of cast iron may be similarly provided with or wiiout a sheath or recess containing flux material. Moreover, the rod may be provided with a pressed-on iron-powder and graphite containing covering which is partially used up in forming the weld. Such covering, it will be appreciataed, effects a stable electric arc and makes possible a reliable welding operation using either direct or alternate current.

In accordance with a preferred embodiment of the invention, a steel wire having 0.05 to 1.3% carbon, 0.03-0.5% silicon, O.10-1.5% manganese, 0.02-0.07% phosphorus, 0.02-0.05 sulfur, may be used as a core wire upon which a covering containing the necessary carbon and silicon may be disposed which will contribute the necessary ingredients during the melting and welding period.

The ingredients of such fluxes are 45% fiuorspar, 25 to 50% graphite, 5 to 15%, rutile, 10 to 40% ferro-silicon of 45% silicon content (or equivalents), 5 to 10% ferro-titanium or 30% titanium content (or equivalent), 0 to 2% aluminum, 0 to 20% iron powder.

The thickness of the covering is preferably such that its outer diameter is about 1.1 to 1.5 times the diameter of the core.

Other constituents, such as aluminum and magnesium, for regulating the graphitizing of the weld may be incorporated in the addition rods in a minor amount, i.e. 0.01-0.5%. Nickel for the purpose of increasing the toughness of the Weld, and chromium, for the purpose of increasing the hardness, may also be incorporated in the Welding rod in amounts up to 1.0% each, i.e. 0.ll%, and for chromium even up to 1.3

It will be appreciated that the addition welding rods in accordance with the invention are suitable not only for forming welds of cast iron but also for adding Wearresistant coating Welds upon cast iron surfaces. Besides erforming the welding operation by means of a gas flame or an electric arc in the customary manner, the rods may also be Welded with the application of protective gase such ar argon, helium, carbon dioxide, etc, and mixtures thereof.

The Welds achieved in accordance with the invention are particularly suitable for cast iron parts which may be subjected to exposure to stresses at high temperatures, even where a metal becomes red hot and the exposure is over prolonged periods of time and is frequently repeated. Generally, the welds in accordance With the in vention resist such stresses in the same manner as the base cast iron material. A particular advantage in ac cordance with the invention is the fact that even with large and heavy cast iron parts, the conventional preheating step to temperatures of 600 C. and higher, may be omitted altogether, or else only a slight preheating up to about 200 C. may be used.

In accordance with the foregoing,

preferably; 20 to the percentages er:- are percentages by weight and the carbon, silicon, manganese, phosphorus, sulfur, nickel, chromium, magnesium and aluminum are expressed as additions to the basic cast iron material which generally contains ledeburite, perlite and graphite.

Percent Carbon 1.5-2.8 Silicon 1.5-2.7 Manganese 0.3-1.2

Remainder substantially iron.

2. In the process of welding cast iron by applying an iron welding rod material at welding temperatures to the cast iron surfaces to be welded, the step which comprises carrying out said welding by applying at the welding temperature to the cast iron surfaces to be welded, after the reaching of a preheating temperature of at most about 200 C., an iron welding material containing:

Percent Carbon 1.5-2.8 Silicon 1.5-2.7 Manganese 0.3-1.2 Phosphorus Q. 0.02-0.07 Sulfur 0.02-0.05

Remainder substantially iron in the form of a welding rod containing a steelwire core having a carbon content of 0.05-1.3%, a silicon content of 0.03-0.5%, a manganese content of 0..l-1.5%, a phosphorus content of 0.02-0.07%, and a sulfur content of 0.02-0.05%, and a covering comprising carbon, silicon, and any manganese to complete the percentage required and at least one of nickel (0.01-1%) or chromium (0.1-1.3%).

3. In the process of welding cast iron by applying an iron welding rod material at welding temperatures to the cast iron surfaces to be welded, the step which comprises carrying out said welding by applying at the welding temperature to the cast iron surfaces to be welded, after the reaching of a preheating temperature of at most about 200 C., an iron rod welding material containing:

Percent Carbon -4. 1.5-2.8 Silicon 1.5-2.7 Manganese 0.3-1.2 Phosphorus 0.02-0.07 Sulfur 0.02-0.05

Remainder substantially iron.

4. Improvement according to claim 3, wherein said welding material additionally contains 0.1 to about 1% nickel.

5. Improvement according to claim 4, wherein said welding material additionallycontains 0.1 to 1.3% chromium.

6. Improvement according to claim 5, wherein said welding material additionally contains a minor amount (0.01 to 0.5%) of at least one of magnesium or aluminum.

' 7. Cast iron welding rod material containing:

Percent Carbon 1.5-2.8 Silicon 1.5-2.7 Manganese 0.3-1.2 Phosphorus 0.02-0.07 Sulfur 0.02-005 Remainder substantially iron wherein said rod includes a steel wire core having a carbon content of 0.05-1.3%, a silicon content of 0.03- 0.5%, a manganese content of 0.10-1.5%, a phosphorus content of 0.02-0.07% and a sulfur content of 0.02- 0.05%, and a covering comprising carbon, silicon, and any manganese to complete the percentage required and at least one of nickel (0.1-1%) or chromium (0.1-1.3%).

8. Cast iron welding rod material according to claim 7 wherein said welding rod material has a flux of the following composition:

Percent Fluorspar 20-45 Graphite 25-50 Rutile 5-15 Ferrosilicon (45% Si) 10-40 Ferrotitanium (30% Ti) 5-10 Aluminum i 0-2 Iron-powder 0-20 References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noo 3 ll l O33 December 1O 1963 Curt Christian Elster et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2. line 2 for "3.03,7" read 3.4-3.7 line 48 for "content" read contents column 4. line 353 for "15%" read 15% column 5 line 36 for "0.0l-l%" read 0 ll% a,

Signed and sealed this 5th day of May 1964.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents

Claims

1. IN THE PROCESS OF WELDING CAST IRON BY APPLYING AN IRON WELDING ROD MATERIAL AT WELDING TEMPERATURES TO THE CAST IRON SURFACES TO BE WELDED, THE STEP WHICH COMPRISES CARRYING OUT SAID WELDING BY APPLYING AT THE WELDING TEMPERATURE TO THE CAST IRON SURFACES TO BE WELDED, AFTER THE