Using welding know-how to extend service life

Our welding know-how:

1.  In-house development of procedures
2. Own production facilities
3. Wear compliance quality check
4. Worldwide pooling of experience
5. Support for difficult deposition welding problems
6. Process development

There are three things to consider in order to carry out hardfacing successfully.
These are:

• Checking the weldability of the basic material.
• Selection of the appropriate VAUTID deposition welding material.

• Selection of the appropriate welding method.

Checking the weldability of the basic material:

The following generally apply:

• Non-alloyed steels / cast steel grades up to 0.3 %C (magnetic, soft):
  Can be welded without special arrangements!
• Alloyed steels and steels over 0.5% C (magnetic, hard):
  Unsuitable for welding as prone to cracks! However, deposition welding is possible by pre-heating the workpiece to approx. 200 to 300 °C or by the prior application of VAUTID buffer layers.
• Manganese hard cast steel and manganese hard steel (not magnetic):
  Weld cold, cool with water or air. For difficult applications, it is recommended to weld a buffer layer with VAUTID buffer materials in advance.
• Grey cast iron and spheroidal graphite cast iron (magnetic, soft, fading black:
  Highly unsuitable for welding as prone to cracks. However, deposition welding is possible by the prior application of VAUTID buffer layers.
• Chilled iron (magnetic, hard):
  Highly unsuitable for welding due to risk of cracking! However, under certain conditions, deposition welding can also be carried out, with careful control on the welding current.
• Austenitic steel and cast steels like stainless steels and heat resistant steels (not magnetic or only very weakly magnetised, stainless):
  Can be welded without special arrangements!

Weldability can also be checked using the VAUTID 18/8/6 rod electrode. A file test will determine whether deposition welding has caused hardening of the main body. Hardening means unsuitability for welding.

Before hardfacing a suitable main body, the area to be welded must be cleaned with a grinding disc to remove any contamination, such as dirt or rust. It is important to check that the main body does not contain any cracks.

Enclosed rod electrodes and cored wires both have their advantages and disadvantages.

The major benefit of the rod electrode is that it is easy to use in almost all welding situations, and only needs a low-curent power source.

The drawback is that it has a relatively low melting power of between approx. 1 and 2 kg /h. In contrast, cored wires cored wires have a markedly higher melting power of approx. 5 - 15 kg /h. However they can usually only be used in the flat position and require very much larger welding machines.

As regards selection of the welding current sources, the following must be noted:

Manual electrode welding:

The usual power sources for manual electrode welding with falling characteristic curves are suitable providing they allow a continuous load of at least 200 A. All VAUTID electrodes can be used for direct current or alternating current welding, whereby the + pole should be selected for direct current welding.

Cored wire welding:

The common MIG/MAG welding machines can be considered for VAUTID cored wires provided the wire feed is made with at least 4 driven rollers. These must not deform the cored wire - attention should be paid to the rolle contact pressure and to the selection of smooth or knurled feeder rollers. All VAUTID cored wires are welded on the plus pole – i.e. with direct current. The power source should have a continuous rating of at least 26 V / 350 A. Data sheets must be checked to establish whether gas shielding is required or whether open arc welding can be used; i.e. welding without gas shield. Most of the VAUTID cored wires are designed for welding withou gas shield.

The following questions must be answered before carrying out hardfacing.

1. Which base material is involved?
2. What ist the welding load, which VAUTID deposition welding material can be selected?
3. Which welding method should be used?