DE1533961B1 - Process for the production of easily weldable objects made of spheroidal graphite cast iron by fusion welding - Google Patents

Description

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The invention relates to a method for manufacturing, at least for welding

decarburization of provided zones that are easily weldable by fusion welding. The decarburization must

Articles made of spheroidal graphite cast iron. to be carried out until in the field of

It is known that the material cast iron with zones intended for welding is carbon-spheroidal graphite Basically, there is a poor sweat content, such as that of weldable steel suitability owns, because because of the chemical to-varieties are known. After this decarburizing Composition in the area of the heat affected zone annealing then takes place normal cooling until Structural changes occur during the welding process, to room temperature. It can be used for setting change the mechanical properties. certain usage properties of the material The defects in the welded joint are generally necessary, then heat treatment common in the fact that at the transition point welding in the sense of a soft annealing or tempering Insufficient mechanical feed of base material. The weldability is in this condition Properties are present, as a result of which the workpiece is present according to the invention. Ever Welding shrinkage tensions cracks between weldments according to the stresses applied to the weld deposit and base material can arise, as this 15 bond is made in practical use Tensions from the connection are no longer released, it is possible to remove the welded workpiece could be taken. In addition, there is no need for further thermal post-treatment the weld joint has a higher hardness and turn; but also such a a reduction in toughness, which is also readily followed by heat treatment make the welded joint unsuitable. Turn 20.

It is known that malleable cast iron can be decarburized. The invention is based on the following example

of the glow to make weldable, but this described.

Material has a completely different chemical composition

composition as cast iron with spheroidal graphite. In addition to the chemical composition, the following values

In addition, the experience with the 25 demonstrates that welding should be carried out,

carbonization of black malleable cast iron (in which the 3 29 «/ Γ

Carbon in the form of free tempered coal before- 2 ^ 9 o / ° ς · '

lies) a prejudice developed, since the Eigen- o'l7 ° / ° Mn

shafts of black malleable cast iron through the _n ' _n <- _{0 /} °, »'

decarburizing annealing were deteriorated. Despite 30 ^υ '^{υ:> / oMgj}

the further existing general knowledge that common additives and impurities,

white malleable cast iron by a decarburizing annealing remainder iron.

is largely suitable for welding, this could be The workpiece with a vorbeikenntnis for welding not on black malleable cast iron or on wall thickness of 7 mm is then during a such malleable cast iron are transferred, which 35 time of 48 hours in an oxidizing Contains free carbon because it is heated to 1070 ° C in the core of the atmosphere. Through this glow white Malleable cast iron is still pretreated with tempered carbon, the carbon content in the edge hands and this core has a pearlitic structure, d. H. so also in the welding zones has, the disadvantages of which are reduced by about 0.2% C in black malleable cast iron. Then leave that have already been mentioned. 40 Cool the workpiece to room temperature and

Attempts have therefore been made to remedy these defects by subsequently subjecting it to a heat treatment, Spheroidal graphite cast iron by using it by heating it to 740 ° C, Different welding processes or through the loading process. Such a workpiece can then be harmless Use of different welding consumables to be welded according to all occurring processes remedy. However, none of these attempts have resulted in any reduction in strength practical solution out, so that only one of the base material occurs here. If you fit the There is a limited possibility of welding consumables with regard to the metallic To carry out a bond weld if the alloy components are the basic specialty in terms of strength and elaborate precautionary measures are used, the welded joint is also preserved are attacked. Very often, to bypass this 50, a strength corresponding to the base material had to be achieved. Difficulties in place of the material spherical- This was previously possible with the material cast iron cast graphite another material can be used. Do not achieve spheroidal graphite. If the welding

The invention is based on the object, carried out by methods in which no bond

the above-described deficiencies in the welding welding filler material is used, so

to fix spheroidal graphite cast iron. 55 then the welded connection also receives the

To solve this problem, it is proposed that the base material speed.

To subject the castings to a decarburizing annealing treatment and the temperature range between 900 and 1200 ⁰ C before the associated reduction in the carbon of the weld, whereby the carbon content increases the melting point of the material content in the weld zone to a 60 substance in the Welding zone is reduced to such a temperature content of less than 0.3%, areas as they are common with steel materials.

The alloy to be used according to the invention is thereby a technically perfect execution

all nodular cast iron grades with pearlitic a connection weld with steel are guaranteed.

and ferritic structure, such as B. in the norm. Furthermore, the low carbon

DIN1693 are described. 65 content in the area of the welding heat-affected zone in

Are workpieces made of these alloys of a base material cast iron with spheroidal graphite during

decarburizing or oxidizing annealing in the temperature of welding no damaging microstructure

temperature range between 900 and 1200 ⁰ C under- the mechanical properties of the

Claims (1)

3 4 Disturb the welded connection or the too macroscopic cast iron with spheroidal graphite, thereby g e - errors in the connection. indicates that the castings are one decarburizing annealing in the temperature range Claim: between 900 and 1200 ⁰ C before welding 5, whereby the carbon process for the production of melt content in the area of the welding zone is reduced to one weld easily weldable objects from a content of less than 0.3% is reduced.