Abstract:In the AiF‐FOSTA research project P1020 [1], a new design model for welded joints was developed. In this context, a small scale test on flat tensile specimens was designed, with the help of which various influences on the strength and ductility of the welds were investigated. Furthermore, extensive tests were carried out on overlap joints, cruciform joints with double fillet welds as well as partially and fully penetrated butt joints. This was done to calibrate the weld construction factor αw, which takes into… Show more
“…The influence of the material combination, number of layers, opening angle of the weld seam, type of manufacturing (welded manually and automatically) and the cooling time t 8/5 (measured with thermo-sensors in the liquid weld metal) was investigated. Descriptions of the experimental procedure, geometry of the specimens and results are given in detail in Stroetmann (2020) and in summary in Stroetmann (2018) and Stroetmann and Kästner (2021). The significant factors influencing the mechanical properties of the WM were identified as the filler metal used and the cooling time t 8/5 .…”
Section: Properties Of Weld Seams and Hazmentioning
confidence: 99%
“…The decrease in strength is more pronounced in the cooling time interval from 5 to 12 s than in the interval from 12 to 20 s. It can also be seen that, with the exception of filler metal G79, the characteristic tensile strengths determined in the cooling time interval are above the nominal tensile strengths of the filler metals. In particular, high strength reserves were identified for low strength filler metals, which are not considered in the current design rules.Figure 6.Nominal filler metal strength (lines) and characteristic tensile strengths (points) f wu,k of selected filler metals (G35 to G89) depending on the cooling time t 8/5 according to Stroetmann and Kästner (2021).…”
Section: Properties Of Weld Seams and Hazmentioning
confidence: 99%
“…Nominal filler metal strength (lines) and characteristic tensile strengths (points) f wu,k of selected filler metals (G35 to G89) depending on the cooling time t 8/5 according to Stroetmann and Kästner (2021).…”
Section: Properties Of Weld Seams and Hazmentioning
As the strength of steels increases, it becomes more and more difficult to produce welded connections whose mechanical-technological properties correspond to those of the base material. The choice of welding process, filler materials and temperature control are of great importance for the connection properties. This concerns not only the weld seam itself but also the heat-affected zone. Especially in the case of high-strength fine-grain steels with low carbon content, where the strength properties are specifically adjusted by a combination of alloying concepts and heat treatment, and if necessary, rolling at defined temperatures, the importance of softening the heat-affected zone (HAZ) increases. This article gives an overview about current manufacturing processes of high-strength fine-grained structural steels and summarizes normative and manufacturer-related specifications for their welding processing. The influence of the cooling time on the mechanical properties of the HAZ and the weld metal is clarified, and possible failure modes of welded connections with softening of the HAZ are described. Finally, the future European design rules for welded connections are explained and a newly developed design model is presented.
“…The influence of the material combination, number of layers, opening angle of the weld seam, type of manufacturing (welded manually and automatically) and the cooling time t 8/5 (measured with thermo-sensors in the liquid weld metal) was investigated. Descriptions of the experimental procedure, geometry of the specimens and results are given in detail in Stroetmann (2020) and in summary in Stroetmann (2018) and Stroetmann and Kästner (2021). The significant factors influencing the mechanical properties of the WM were identified as the filler metal used and the cooling time t 8/5 .…”
Section: Properties Of Weld Seams and Hazmentioning
confidence: 99%
“…The decrease in strength is more pronounced in the cooling time interval from 5 to 12 s than in the interval from 12 to 20 s. It can also be seen that, with the exception of filler metal G79, the characteristic tensile strengths determined in the cooling time interval are above the nominal tensile strengths of the filler metals. In particular, high strength reserves were identified for low strength filler metals, which are not considered in the current design rules.Figure 6.Nominal filler metal strength (lines) and characteristic tensile strengths (points) f wu,k of selected filler metals (G35 to G89) depending on the cooling time t 8/5 according to Stroetmann and Kästner (2021).…”
Section: Properties Of Weld Seams and Hazmentioning
confidence: 99%
“…Nominal filler metal strength (lines) and characteristic tensile strengths (points) f wu,k of selected filler metals (G35 to G89) depending on the cooling time t 8/5 according to Stroetmann and Kästner (2021).…”
Section: Properties Of Weld Seams and Hazmentioning
As the strength of steels increases, it becomes more and more difficult to produce welded connections whose mechanical-technological properties correspond to those of the base material. The choice of welding process, filler materials and temperature control are of great importance for the connection properties. This concerns not only the weld seam itself but also the heat-affected zone. Especially in the case of high-strength fine-grain steels with low carbon content, where the strength properties are specifically adjusted by a combination of alloying concepts and heat treatment, and if necessary, rolling at defined temperatures, the importance of softening the heat-affected zone (HAZ) increases. This article gives an overview about current manufacturing processes of high-strength fine-grained structural steels and summarizes normative and manufacturer-related specifications for their welding processing. The influence of the cooling time on the mechanical properties of the HAZ and the weld metal is clarified, and possible failure modes of welded connections with softening of the HAZ are described. Finally, the future European design rules for welded connections are explained and a newly developed design model is presented.
“…The influence of HAZ softening on the loadbearing capacity of brace connections has been investigated in only a few research projects so far. The scope of AiF-FOSTA research project P1020 [24,25] included investigating the influence of the peak temperature and cooling time t 8/5 on the mechanical properties of highstrength steels in addition to developing a new design model for welded connections [10]. The temperaturetime curve of a welding process was thermo-physically simulated in a BÄHR DIL 805 dilatometer on flat tensile specimens of steel grades S500ML, S700MC, S690QL and S960QL.…”
Section: Articlementioning
confidence: 99%
“…The loadbearing capacity of welds can be determined, for example, according to the directional or the simplified method of EN 1993-1-8 [2]. An overview of the design of welded connections and current developments is given by the authors in [10]. The effective weld length is of particular importance for the determination of the loadbearing capacity of welded connections at hollow section joints.…”
The calculation of the loadbearing capacity of hollow section joints using the design formulas according to EN 1993-1-8 assumes full-strength welded connections if the non-linear stress distribution over the circumference is not covered by calculation. Sufficient ductility in the connections ensures a plastic redistribution capacity within each joint. In the case of hollow section structures made of high-strength steels, it becomes more difficult to meet the requirement for full-strength welds as the yield strength of the base material increases. This article begins with a summary of the current rules for the design and execution of welded hollow section joints. The softening behaviour of high-strength steels and the loadbearing capacity of welded connections with local softening in the HAZ are then discussed. That is followed by the presentation of the results from the AiF-FOSTA research project P1020 regarding the influence of manufacturing parameters on the properties of welded connections and the HAZ. The experimental test programme for single-sided welded T-connections and the parameter studies within the research project P1453 are also described. Finally, a design approach is presented to account for HAZ failure and hybrid failure modes of hollow section connections.
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