Hydrogen-induced cold cracking is a treacherous defect type in the weld seam and in the heat-affected zone – and not merely due of its delayed appearance. Frequent causes include welding filler materials such as SAW fluxes, cored wire electrodes or stick electrodes.
With our accredited analyses (DIN EN ISO 3690), we inspect and qualify weld filler materials with regard to their hydrogen content. We create defined weld specimens and analyze them with the carrier gas hot extraction method or the mercury method.
Cold cracks are intercrystalline or transcrystalline material separations in the heat-affected zone or in the weld metal that occur when welding. The general cause is a critical relationship among hydrogen content, mechanical stress and microstructure.
To assess the cold cracking susceptibility of base and filler materials, we offer recognized, self-restraint cold cracking tests, which can also be used for suitability and acceptance testing.
To prevent hydrogen-induced cold cracking, the moisture content of electrode coatings and welding fluxes ideally comply with a specified value.
Both for control during production and for in-process monitoring in welding technology-based manufacturing operations, we offer moisture analysis based on the infrared method (AWS A 4.4M).
Whether it involves pipe or sheet material that meets the prescribed mechanical-technological properties in the heat-affected zone, we inspect with welding tests. These properties are specified in the general regulations (DNV OS-F101, API RP 2Z, DIN EN 10225 or API 1104 etc.) as well as in special customer specifications. We have extensive experience with all standard welding processes:
We offer weldability tests (welding tests) on many base materials:
In assessing the weldability of steel materials, the tendency of the material to harden in the heat-affected zone is an important criterion. We determine this property quantitatively with a GTA deposition weld.
Welding parameters, preheat temperatures and other conditions are specified in British Standard BS 7363.
Proof of the joining technology processability of a material is generally determined for each joining method according to SEP 1220 (Stahl-Eisen-Prüfblatt = test specification for iron and steel).
SEP 1220-2 covers
Specimen shapes and testing conditions are essentially comparable to those of SEP 1220-2 for spot welding. As a quality limit for a specified laser power, the test considers the maximum achievable feed rate at which full penetration can still be reached on the doubling of the analyzed sheet material. Unlike with SEP 1220-2, the welds additionally undergo an X-ray inspection as well as a hot cracking test.
SEP 1220-4 describes the material release process for gas metal arc brazing and SEP 1220-5 describes the material release process for gas metal arc welding. Specimen shapes and testing conditions are essentially comparable with those of SEP 1220-2. In this case, however, typical methods do not produce lap joints, but rather fillet welds. Testing conditions for gas metal arc brazing and gas metal arc welding are the same. With regard to quality limits, the minimum and maximum allowable connection cross-sections are determined for a specified process speed. Unlike with SEP 1220-2, the welds additionally undergo an X-ray inspection. A hot cracking test is also conducted.