DE2819523A1 - ADDITIONAL MATERIAL FOR THE FORMATION OF HIGH STRENGTH WELDED JOINTS AND PROCESS FOR ITS PRODUCTION - Google Patents

Description

Case TK.1

DESCRIPTION

The invention relates to a filler material or a filler for the formation of welded connections or weld seams with high mechanical strength between parts made of spheroidal cast iron or nodular cast iron, as well as a
Process for the production of this filler material.

The welding of spherical cast iron (by oxy-fuel welding (oxygen / acetylene torch) or arc welding) has so far been used more for repair work than to join two parts together during their manufacture, since the mechanical strength of the welded joint or weld seam is always much lower than
that of the base metal. If, for example, two components made of spherical cast iron are joined by welding with the aid of welding rods used for autogenous welding, the weld seam formed is generally not
good, because the welded connection has a significantly lower mechanical strength than the parts connected to one another. Typically the strength is the

0 weld joint about 20-25 kg / mm compared to that

2
Strength of 50 - 90 kg / mm of the connected parts.

The reason for this reduction in mechanical strength is to be seen in the fact that in those areas of the cast iron that are melted during welding, the graphite does not precipitate in spherical form, but in
Form of flake graphite, so that the microstructure and the
mechanical properties of these areas correspond to those of a simple gray cast iron.

It is therefore readily apparent that this

0 welding of spherical cast iron can only be carried out on parts that are not subject to heavy loads are exposed.

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Case TK 1.

Teksid S.p.A ^ e 19523

The disadvantages mentioned can be avoided to a certain extent by using high quality welding tools Filler materials, such as nickel, are used to achieve acceptable welded joints can. However, these welded joints have in the

2 Practice a strength of less than 50 kg / mm and suffer on the naphthole that the resulting ductile iron-nickel-ductile iron joint tends to corrode because of the different contact potentials.

The object of the present invention is therefore to provide a filler material for the formation of high-strength tear connections between parts of spherical cast iron and a process for its. Manufacture to indicate with which Filler metal welds or welds can be formed that are welded with respect to the Components are homogeneous and which additional materials are cheap and are easy to manufacture.

According to the invention, this object is achieved by a filler material for the formation of high-strength welded joints Parts made of spherical cast iron, which is characterized in that it contains an agent that the formation or deposition of spheroidal graphite during the casting of the molten filler material and during use of the filler material to form a welded joint causes or induces.

The invention also relates to a method for production this filler metal, which is characterized in that one

1. 80-90% by weight of spheroidal cast iron or nodular cast iron, 0.5-10% by weight and preferably 5% by weight nickel, 0.5-15% by weight and preferably 2% by weight copper and 1-10 wt .-% and preferably 5 wt .-% of an iron metal containing rare earth metals and preferably cerium

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alloy melts and mixes and

2. Pour the molten mixture at a temperature of about 1450 ° C.

An essential feature of the production of the invention Filler material is to be seen in introducing a means into the filler material material that the training or deposition of spheroidal graphite and has a high boiling point so that it does not have its effect only during the casting of the filler metal, but also later, d. H. during its use for education a welded joint.

The composition of the filler material according to the invention is similar to that of a typical spherical cast iron (2.7-3.4 wt% carbon and 1.8-3.2 wt% silicon); However, the filler material is both an additive that acts during certain stages of the welding process and a Deposition of graphite in spherical form, and additives that lead to good mechanical properties of the Weld joint contribute enriched. These additives or additions improve the properties of the invention Filler metal, either in the form of welding rods or welding wires used for autogenous welding or in the form of electrodes for arc welding can be.

The filler material according to the invention preferably has the following composition:

1.5-5% by weight, preferably 3.2% by weight silicon 1-4% by weight, preferably 3% by weight carbon 0.5-10% by weight, preferably 5% by weight, nickel containing 0.5-2% by weight, preferably 0.8% by weight, cerium

Rare earth metals

0.5-15% by weight, preferably 2% by weight, copper 0.1-2% by weight, preferably 0.3% by weight manganese

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less than 0.05 wt% and preferably less than 0.010 wt% sulfur
Remainder iron.

The method for producing the filler material according to the invention is preferably carried out in such a way that first a mixture of 80-90 wt .-% residues made of spherical cast iron, which arise during casting in the pouring openings and in the risers of the casting molds, 0.5-15% by weight of copper and 1-10% by weight of an iron alloy containing rare earth metals, including preferably cerium, melts.

Particular care should be taken when weighing in the quantities of nickel and copper depending on the desired properties of the filler metal. For example, can use a mixture of 5 wt .-% nickel and 2 wt .-% copper, whereby one obtains a filler material which exhibits good flowability when welded and gives a welded joint of good strength.

The iron alloy containing the cerium is preferably carried directly into the at the last moment before casting Casting mold to prevent oxidation of the rare earth metals contained in the iron alloy. It is still advisable to to introduce the iron alloy in the form of fine droplets into the casting mold in order to achieve better homogenization reach.

Potting takes place in molds at a temperature of around 1450 ° C
4-6 mm.

1450 ° C in molds, the rods with a diameter of

For the formation of electrodes for arc welding, the rods are covered with the usual electrode covering materials covered, for example an acidic coating material (the iron oxide; iron-manganese; iron-silicon or titanium oxide

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28T9523

contains) or alternatively a shell material that is obtained from such an acidic shell material and rutile (titanium oxide).

Before welding, cast parts with different thicknesses must be preheated to a temperature of 500 - 600 ° C, to avoid the possible formation of internal stresses after welding.

For the autogenous welding one must use suitable flux in paste form or in powder form to the surface to etch the base metal and remove the oxides covering it without affecting the wetting of the metal surface. For welding spherical cast iron, for example, flux based on use of borax.

After welding is a heat treatment, in general referred to as postheating, is required to remove the carbides and relieve internal stresses.

However, the details of the welding measures are known. The filler material according to the invention is thus used known welding techniques are used, with no other types of devices or additives or auxiliaries are required than they have previously been used for welding. According to the invention, the considerable achieve technical progress that, after a suitable heat treatment, welded joints or welded

seams with a mechanical strength of up to 90 can form.

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Claims (7)

2619523 Patent Attorneys Dipl.-Ing. H.Weickmann, Dipl.-Phys. Dr. K. Fincke Dipl.-Ing. FA "Weιckmann, Dipl.-Chem. B. Huber Dr.-Ing.H. Liska 8 MUNICH 86, DEN * 3 · Μβί 1978 POST BOX 860 820 MDHLSTRASSE 22, CALL NUMBER 98 3921/22 Case TK.1 tM / ei TEKSID SpA ^ Corso Mortara 7, Turin, Italy Filler material for the formation of high-strength welded joints and its manufacturing process. PATENT CLAIMS 1. Filler material for the formation of high-strength welded joints between parts made of spherical cast iron, characterized in that it contains an agent which causes the formation of spheroidal graphite when pouring the molten filler material and when using the filler material for formation causes a welded connection. 909813/0664 OBiGlNAHNSPECTED Teksid S.p.A. 2. Filler material according to claim 1, characterized by the following composition: a) 1-5% by weight silicon b) 1-4% by weight carbon
c) 0.5-10% by weight nickel d) 0.5-2% by weight rare earth metals e) 0.5-15% by weight of copper f) 0.1-2% by weight of manganese g) less than 0.05 wt .-% sulfur h) the remainder iron 3. Filler material according to claim 2, characterized by the following composition: 3.2 wt% silicon 3 wt% carbon
"5 wt% nickel 0.8% by weight rare earth metals 2 wt% copper 0.3% by weight manganese less than 0.010 wt% sulfur
0 remainder iron 4. Zusat.zwerkstoff according to claims 2 or 3, characterized in that it is used as Contains rare earth metals or cerium as one of the rare earth metals. 5. Process for the production of the filler material according to the Claims 1 to 4, characterized in that that he 1. 80-90% by weight spherical cast iron, 0.5-10% by weight nickel, 0.5-15% by weight copper and 1 10 % By weight of an iron alloy containing rare earth metals melts and mixes and 2. Pour the molten mixture at a temperature of about 1450 ° C. 909813/0664 Case TK.1 6. The method according to claim 5, characterized in:. draws that a mixture of 80 - 90% by weight spherical cast iron, 5% by weight nickel, 2 wt .-% copper and 5 wt .-% of an iron alloy containing rare earth metals are used. 7. The method according to claims 5 and 6, characterized thereby. Inet that you get the rare earth metals containing iron alloy in the form of fine droplets directly into a molten mixture of cast iron, Brings ladle containing nickel and copper. 909813/0664