Hot cracking tests—an overview of present technologies and applications

Kannengießer, Thomas; Boellinghaus, Thomas

doi:10.1007/s40194-014-0126-y

Cited by 54 publications

(25 citation statements)

References 17 publications

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“…Specimen thickness is usually not varied within a series of experiments, but regarded to be a significant influence on test results [34]. This aspect becomes even more complex when considering that nominal applied strain often deviates significantly from the actual local deformations in the vicinity of the weld pool, which pose the critical factor but at the same time are highly inhomogeneous [35]. Travel speed has been reported to be the most complex [34] or even critical [36] parameter, said to increase [37] or to decrease [38] cracking under otherwise equal conditions.…”

Section: Solidification Cracking and Suitable Testing Methodsmentioning

confidence: 99%

Surface- and volume-based investigation on influences of different Varestraint testing parameters and chemical compositions on solidification cracking in LTT filler metals

et al. 2020

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The subject of this study is how, and to what extent, Varestraint/Transvarestraint test results are influenced by both testing parameters and characteristics of evaluation methods. Several different high-alloyed martensitic LTT (low transformation temperature) filler materials, CrNi and CrMn type, were selected for examination due to their rather distinctive solidification cracking behaviour, which aroused interest after previous studies. First, the effects of different process parameter sets on the solidification cracking response were measured using standard approaches. Subsequently, microfocus X-ray computer tomography (μCT) scans were performed on the specimens. The results consistently show sub-surface cracking to significant yet varying extents. Different primary solidification types were found using wavelength dispersive X-ray (WDX) analysis conducted on filler metals with varying Cr/Ni equivalent ratios. This aspect is regarded as the main difference between the CrNiand CrMn-type materials in matters of cracking characteristics. Results show that when it comes to testing of modern highperformance alloys, one set of standard Varestraint testing parameters might not be equally suitable for all materials. Also, to properly accommodate different solidification types, sub-surface cracking has to be taken into account.

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Section: Solidification Cracking and Suitable Testing Methodsmentioning

confidence: 99%

Surface- and volume-based investigation on influences of different Varestraint testing parameters and chemical compositions on solidification cracking in LTT filler metals

et al. 2020

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“…The heat transfer between the test specimen and the die block is also difficult to model, and it requires a contact analysis, which makes the FE analysis much more computational heavy. A better weldability test for calibrating and testing the WSC model on sheet metals is the controlled tensile weldability (CTW) test, developed at BAM Fedral Institute for Materials Research and Testing [3]. In this test, the test specimen is again a plate, but is now loaded in pure tension.…”

Section: Validationmentioning

confidence: 99%

“…The crack can be small and is therefore difficult to detect by nondestructive test methods. It can act as an initiation site for fatigue and corrosion cracking [3], which can be expensive to repair. The formation of the crack depends on the welding process, e.g., changes in weld heat input, welding speed, and external restraints from fixturing can all influence the crack susceptibility [1,4].…”

Section: Introductionmentioning

confidence: 99%

Modeling and simulation of weld solidification cracking part III

et al. 2019

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Several advanced alloy systems are susceptible to weld solidification cracking. One example is nickel-based superalloys, which are commonly used in critical applications such as aerospace engines and nuclear power plants. Weld solidification cracking is often expensive to repair, and if not repaired, can lead to catastrophic failure. This study, presented in three papers, presents an approach for simulating weld solidification cracking applicable to large-scale components. The results from finite element simulation of welding are post-processed and combined with models of metallurgy, as well as the behavior of the liquid film between the grain boundaries, in order to estimate the risk of crack initiation. The first paper in this study describes the crack criterion for crack initiation in a grain boundary liquid film. The second paper describes the model required to compute the pressure and thickness of the liquid film required in the crack criterion. The third and final paper describes the application of the model to Varestraint tests of alloy 718. The derived model can fairly well predict crack locations, crack orientations, and crack widths for the Varestraint tests. The importance of liquid permeability and strain localization for the predicted crack susceptibility in Varestraint tests is shown.

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“…However, the solidification range of the materials can be broadened by adding the alloying elements, and thus, the hot cracking susceptibility is increased. The metallurgical and thermal-mechanical conditions during solidification are crucial for hot cracking [6]. The occurrence of hot cracking has been studied on different length scales.…”

Section: Introductionmentioning

confidence: 99%

Investigation on hot cracking during laser welding by means of experimental and numerical methods

et al. 2017

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Hot cracking during laser welding of Transformation Induce Plasticity (TRIP) steel at the edges of steel flanges can be a problem. In this study, modified hot cracking tests were performed by welding on a single-side clamped specimen at various distances from the free edge, while the heat input and external constraints remained constant. In situ temperature and strain measurements were carried out using pre-attached thermocouples and digital image correlation, respectively. A thermal-mechanical finite element (FE) model was constructed and validated with the temporal and spatial data measured. From the validated FE model, the temperature and strain evolution in the weld mushy zone were studied. A critical strain for the onset of hot cracking in the TRIP steel examined was found to be in the range of 3.2 to 3.6%. This threshold was further evaluated and experimentally confirmed by welding with different heat inputs.

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Hot cracking tests—an overview of present technologies and applications

Cited by 54 publications

References 17 publications

Surface- and volume-based investigation on influences of different Varestraint testing parameters and chemical compositions on solidification cracking in LTT filler metals

Surface- and volume-based investigation on influences of different Varestraint testing parameters and chemical compositions on solidification cracking in LTT filler metals

Modeling and simulation of weld solidification cracking part III

Investigation on hot cracking during laser welding by means of experimental and numerical methods

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