Untitled

Nonaka, Toshiki; Fujita, Nobuhiro; Taniguchi, Hiroki; Tomokiyo, Toshimasa; Goto, Kōichi

doi:10.2320/materia.46.108

Cited by 9 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, although the hardness difference between tM and α in the inter-critically annealed and quenched area of Tempered C30A and Tempered C30B was reduced to the same extent, the CTS of Tempered C30B was nevertheless superior to Tempered C30A. Local ductility is known to be affected by microstructural morphology 17) , and it has been reported that the CTS is improved in the case of an acicular α morphology 20) . Cross-sectional SEM observations obtained after the cross-tension test showed that many voids were formed in the Tempered C30A than Tempered C30B (Fig.…”

Section: Discussionmentioning

confidence: 92%

“…Therefore, it is thought that the local ductility of the inter-critically annealed and quenched area needs to be improved to overcome the decreased CTS. It is known that mechanical properties such as hole expandability are affected by the microstructural morphology of α and M 17,18) , and that smaller hardness difference between α and M results in better local ductility 19) . To date, it has been clarified that the α morphology of inter-critically annealed and quenched areas inherit the α morphology of the base material structure, and that an acicular α of the inter-critically annealed and…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Improved Cross-tension Strength of a Friction-element-welding Joint by Tempering Treatment Using Electric Heating

2023

View full text Add to dashboard Cite

Resistance spot welding is widely used in automobile assembly, but reduction of the cross-tension strength (CTS) is inevitable when using high-strength steel sheets. Therefore, we focused on joining high-strength steel sheets using friction element welding (FEW), which is mainly used to join steel sheets and aluminum alloy sheets, to improve the CTS. However, even when using FEW, the CTS decreases at the joint, when a high-carbon-content steel sheet is used as the lower sheet. This CTS decrease is presumed to be due to the low local ductility caused by the large hardness difference (ΔH n ) between martensite (M) and ferrite (α) in the inter-critically annealed and quenched area during joining. The local ductility of the material having complex structure with hard and soft phases is affected by the structural morphology and ΔH n . Therefore, we attempted to improve the CTS by creating joints whose α of the inter-critically annealed and quenched area was equiaxed or acicular, and performed tempering treatment using electric heating to reduce ΔH n of this part. The results showed that ΔH n decreased at the annealed joint and the CTS improved. Furthermore, the highest CTS was observed at the joint having acicular α when tempering was performed. It was inferred that the reduction of ΔH n using electric heating improved the local ductility and CTS of the area. Furthermore, it was considered that the local ductility and CTS are also influenced by the α morphology.

show abstract

Section: Discussionmentioning

confidence: 92%