Current Seminars

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Lecture event German Association for Welding and Related Processes e.V. District Association Ulm/Neu-Ulm on the importance and estimation of material hardness for welders and welding supervisors

on 18.01.2024 at 19:00 in Ulm and
on 12.03.2024 at 18:30 in Heidenheim

According to ISO 18265, hardness is a material parameter that can provide information about the mechanical properties of a material. Thus, even if the hardness is known, statements can be made about the structural condition of welds and heat-affected zones. For example, no hardness cracks are known on steel welds whose heat-affected zone has a hardness lower than about 350 HV. Therefore, the max. hardness of
heat-affected zones for each material group (ISO 15608) is strictly limited in DIN EN 15614. If the max. hardness values are exceeded, e.g. on the test piece welded according to a preliminary welding procedure specification (pWPS), no certificate of qualification of the welding procedure (WPQR procedure qualification test) can be issued by a certified body. Since welding supervisors and welders rarely perform hardness tests on a regular basis, it is often not possible to assess whether a hardness value is to be considered critical. . In addition, increasingly, both in vehicle technology and in infrastructure technology, the increase in mobile operations with shorter time windows for decisions to be observed. This lecture shows how hardness can be estimated by the simplest means. For this purpose, knowledge is imparted about the causes and positions of the hardness peaks to be expected on welds and the formation or associated hazards of hardness cracks. The method for estimating hardness explained in the lecture uses a hardness comparison between the test piece of unknown hardness and a reference piece of known hardness, based on the Mohs hardness test. For this purpose, various everyday comparison objects with known hardnesses are shown, e.g. screw 8.8 approx. 300 HV5, file approx. 860 HV5. This pre-estimation of hardness in service can save examinations by test laboratories on test pieces that are far outside the permissible range. The hardness of heat-affected zones on welds from the unregulated range, where hardness tests by external testing laboratories are often saved, can be estimated, thus reducing the risk of damage.
The estimation of the hardness on welds explained in this article shows a hardness value, on the basis of which it can be decided which further tests are to be carried out. Furthermore, this method makes it possible to check quickly and easily whether the hardness of a supplied material is within the range of the ordered strength properties.

The room is signposted on the day of the event. The site map serves as orientation.

The large parking lot in the courtyard can be reached via an access road below the bus stop "Bildungszentrum".
Your physical well-being will also be taken care of.
 

We are looking forward to your registration and ask you to send it by email to Mrs. Sandra Janas, s.janas@bz-kassel.de by Monday, 13.11.23 at the latest.

With your registration your participation is binding-you will not receive a confirmation of registration.

You will soon find all subsequent events of the welding technology training institute on the website: www.bz-kassel.de, under the heading "Welding Technology".

Top Topics:
A case of damage to a welded prototype structure made of high-strength aluminum will be presented. Cracks were found next to welds on this during the testing phase. Due to the known problem of strength loss in the HAZ of high-strength aluminum, one question that arose was whether welding had a significant influence on the damage. As an expert for examinations and damage analyses in welding and materials technology, publicly appointed and sworn by the responsible Chamber of Industry and Commerce, such cases of damage are repeatedly investigated and the cause of the damage determined. Often, in addition to determining the cause of the damage, research and advice on how to avoid the damage that has occurred in the future is requested. In order to make the materials engineering findings comprehensible to the public interested in welding technology despite non-disclosure agreements, the circumstances were recreated. The identically occurring damage is presented as fictitious or anonymized cases of damage.

Particularly when legal proceedings are initiated, it is occasionally necessary, after the cause of the damage has been found, to recreate the circumstances (supposedly) causative for the damage and to contrast the artificially produced damage picture with the original one in order to be able to explain the circumstances to a more or less technophile lawyer. In the case of the welded aluminum structure, both the welding sequence and the subsequent surface treatment had a significant influence on the early component failure. This is illustrated using residual stress measurements, chemical analyses, hardness histories, and microsection photographs. The hypothesis developed on the basis of these results concerning the damage process is demonstrated by reproducing the environmental effects on an identically welded component. Finally, the advantages and disadvantages of various remedial measures are discussed and it is shown which remedial measure was chosen and why. The article is the second part of a series on complex damage investigations, which was started with the article "Damage to fine-grained structural steel attributable to residual stresses: causes, effects and simple remedial measures" in DVS Congress 2021.