DE102012012342A1 - Welding steel and/or cast iron materials with high carbon content, comprises applying nickel or a nickel-containing material, as a coating, a layer, a film or paste, on one joint in one of the two parts by thermal spraying or rolling - Google Patents

Abstract

The method comprises applying nickel or a nickel-containing material, as a coating, a layer, a film or paste, on one joint in one of the two parts to be welded together by thermal spraying, arc wire spraying, cold spraying, electroplating, rolling, pressing, gluing, arc-welding or laser welding process, and welding the two parts to each other by laser or electron beam welding. A material made of heat-treated steel with a nickel content of 0.7-4.3% or nodular cast iron with a nickel content of 0.4-4.3% is used for one of the two parts.

Description

The invention relates to a method for welding steel and / or cast iron materials with a high carbon content according to the preamble of claim 1 and according to the preamble of claim 5.

Method of the type discussed here are known. Welds, in particular laser welds or electron beam welds, which are connected to materials that have a high carbon content, tend to embrittle. In order to improve the material properties of these welds, in particular to ductilize, either nickel-containing filler metals are used in welding, or materials are welded together, which themselves have a high nickel content. It is from the DE 10 2007 051 765 A1 the use of a material whose nickel content is in the range of at least 10%, preferably 25% to 30%, and most preferably 72% to 75%. The known methods have the disadvantage that the relatively expensive element nickel is used in a very large area of the material and in very high dosage. This ultimately creates unnecessary costs. In addition, relatively high workplace concentrations of nickel occur.

The invention is therefore based on the object to provide a method which allows an economical use of nickel, in particular its very accurate dosage.

The object is achieved by providing a method having the features of claim 1. This is characterized in that at least for one of two parts to be welded together, a material is used which has a nickel content of at least 0.4%. It has been found that this value is a reasonable lower limit for the nickel content of one of the two parts, whereby parts made of steel and / or cast iron materials with a high carbon content, one of which has a corresponding nickel content, can be welded together Weld seam tends to embrittle.

A high carbon content has a carbon content of at least 0.26%. As a rule, the carbon content is more than 0.5%.

Particularly preferred is a method in which the material of the at least one of the parts to be welded together has a nickel content of at least 0.4% to at most 4.3%, preferably to at least 0.4% to at most 3.5%, particularly preferred from at least 0.7% to at most 3.0%. In the specified concentration ranges welding of the two parts is readily possible without causing embrittlement of the weld.

A method is also preferred which is characterized in that the material comprises steel, preferably made of steel. In particular, the material preferably comprises case hardening steel, preferably with a nickel content of at least 0.4% to at most 3.5%, preferably from at least 0.7% to at most 3.0%, or consists of this. Such case steels are standardized in the Standard DIN EN 10083 , Table 3.

A method is also preferred which is characterized in that the material comprises or consists of tempering steel with a nickel content of at least 0.7% to at most 4.3%. Such a tempering steel is also standardized in the Standard DIN EN 10083-3 ,

Alternatively or additionally, one of the two materials comprises nodular cast iron having a nickel content of at least 0.4% to at most 4.3%, or preferably consists thereof. It is also possible to use nodular cast iron having a nickel content of at least 20% to at most 35%, especially for high temperature applications. However, it has been found that such a high nickel content is not required to achieve the desired ductility of the welds. A nickel content in the specified, smaller range is completely sufficient for this purpose.

This makes it possible overall to achieve the desired effect with nickel concentrations that are significantly lower than conventionally used concentrations. This makes extremely economical use of the element nickel possible, and over alloying of the materials used is avoided. At the same time, only relatively low workplace concentrations of nickel occur.

The object is also achieved by providing a method for welding steel and / or cast iron materials with high carbon content with the features of claim 5. This is characterized in that in at least one of the parts to be welded together nickel or a nickel-containing substance is selectively applied to a joint. In particular, by selective application of nickel or a nickel-containing material on the joint before welding, so not as an additional material during welding, a very economical use of expensive nickel and its very accurate dosage is possible. As a result, in particular, low workplace concentrations of nickel are possible.

We prefer a method which is characterized in that nickel or a nickel-containing substance is applied by thermal spraying. Thermal spraying is a surface coating process in which filler materials, the so-called spray additives, inside or outside a spray burner, off, melted or accelerated in a gas stream in the form of spray particles and spun onto a surface of the component to be coated. The component surface is not melted and only a small thermal load. Preferably, nickel or nickel-containing material is applied by arc wire spraying or cold gas spraying. In the case of arc wire spraying, an arc is ignited between two wire tips of the same or different material. The wire tips melt off and are blown onto the surface to be coated by means of a nebulizer gas. In cold gas spraying, the coating material is applied in powder form at very high speed to the surface to be coated. In this case, a heated to a few 100 ° C process gas is accelerated by expansion in a Laval nozzle to supersonic speed. Subsequently, the powder particles are injected into the gas jet. Due to their high speed in the gas jet, a preceding on or melting of the particles is unnecessary.

An advantage of an application of the nickel or the nickel-containing material on the thermal spraying is that the joint can also be coated with nickel alloys. The disadvantage, however, is that ultimately a relatively coarse layer is formed, which makes post-processing seem necessary.

Alternatively or additionally, it is possible to apply nickel or a nickel-containing substance by selective electroplating. In this case, extremely thin layers in the micrometer range can be achieved, so that no reworking is required. The disadvantage, however, is that corresponding methods are relatively expensive.

Alternatively or additionally, it is possible to spread a nickel-containing substance on the joint. This is preferably painted on as a paint or paste. Other forms of application are conceivable. This is one way to apply the nickel-containing material with a particularly simple method at low cost selectively on the joint. However, it is disadvantageous that paintable substances often comprise binders or other additives which, if appropriate, influence the material properties of the resulting weld seam.

Finally, it is possible, alternatively or additionally, to roll nickel on or to press nickel or a nickel-containing substance onto the joint, to weld it, to weld it to the joint and / or glue it on. In this case, the nickel or the nickel-containing material is preferably rolled as a film on the joint, pressed, welded to them and / or glued. In particular, it is possible to use this wound strip material.

Alternatively or additionally, it is also possible to apply nickel or a nickel-containing substance as a layer by means of an arc welding process. Furthermore, this can also be carried out by laser deposition welding.

Of course, it is also possible to provide both parts to be welded together in the region of the joint with nickel or a nickel-containing material according to one of the embodiments of the method described here. Of course, it is possible to combine the various embodiments with each other.

Finally, a method is preferred, which is characterized in that the parts to be welded together by laser welding or by electron beam welding are joined together. Here, the advantages of the method unfold in a special way, since welds produced by laser or electron beam welding in the range of materials with high carbon concentration are particularly prone to embrittlement. Furthermore, in the laser welding due to the small seam width, the molten volume is relatively small, so that the necessary amount of nickel or nickel-containing material can be kept low.

The methods are preferably used in particular when the weld seam is arranged geometrically such that it is not possible to introduce a filler material during welding. Since the embodiments specified here always concern only the individual parts to be joined together, the problem of geometrical accessibility of the joint does not arise.

An advantage of the method is still found that case hardened components may optionally account for a processing of the case-hardened surface layer.

Overall, it can be seen that with the aid of the method a crack-free weld can be achieved while improving the resulting component / properties-in particular an improved impact strength of the welded joint-while the expensive material nickel is used sparingly, by its exact dosage is possible in particular without superalloy of the weld metal. At the same time, low workplace concentrations of nickel are achieved.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007051765 A1 [0002]

Cited non-patent literature

• Standard DIN EN 10083 [0007]
• Standard DIN EN 10083-3 [0008]

Claims (10)

A method of welding steel and / or cast iron materials with high carbon content, characterized in that at least one of two parts to be welded together, a material is used which has a nickel content of at least 0.4%. A method according to claim 1, characterized in that the material has a nickel content of at least 0.4% to at most 4.3%, preferably up to at most 3.5%, more preferably from at least 0.7% to at most 3.0%. Method according to one of the preceding claims, characterized in that the material comprises steel, preferably made of steel. Method according to one of the preceding claims, characterized in that the material comprises tempered steel with a nickel content of at least 0.7% to at most 4.3%, or that the material nodular cast iron having a nickel content of at least 0.4% to at most 4.3 %, preferably consists of one of said materials. A method of welding steel and / or cast iron materials with high carbon content, characterized in that in at least one of the parts to be welded together nickel or a nickel-containing substance is selectively applied to a joint. A method according to claim 5, characterized in that nickel or a nickel-containing material by thermal spraying, preferably arc wire spraying or cold gas spraying is applied. Method according to one of claims 5 or 6, characterized in that nickel or a nickel-containing substance is applied by selective electroplating. Method according to one of claims 5 to 7, characterized in that the nickel-containing substance is spread on the joint, preferably as a paint or paste. Method according to one of claims 5 to 8, characterized in that nickel or a nickel-containing material, preferably as a film rolled on the joint, pressed, welded to the joint and / or glued, or that nickel or the nickel-containing material as a layer by means an arc welding process or by laser deposition welding is applied. Method according to one of claims 1 to 9, characterized in that the parts to be welded together by laser or electron beam welding are joined together.