S. Mironov

Effect of contamination on microstructure in friction stir spot welded DP590 steel

Abstract In this study, FSSW of DP590 steel was performed using both bare and TiC/TiN coated Si3N4 tool with Ar shielding, and effect of contamination on the microstructure during FSSW was examined. Defect free welds were successfully obtained at all welding conditions. Si, N and O contaminations were clearly found in the weld when bare Si3N4 tool was used without Ar shielding, but the coated tool and Ar shielding could suppress the contaminations. The contaminations caused higher hardness in the vicinity of the pin hole and reduced the weld strength. The present study showed that the prevention of the contaminations could improve the weld strength, especially the cross-tension strength, in FSSW of DP590 steel using Si3N4 tool.

Loss of coherency and interphase α/β angular deviation from the Burgers orientation relationship in a Ti–6Al–4V alloy compressed at 800 °C

The mutual relationship between phases in two-phase titanium alloys, αHCP and βBCC, is such that: {0001}α||{110}β;

Microstructural Evolution During Friction Surfacing of Dissimilar Aluminum Alloys

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Texture Produced by Abnormal Grain Growth in Friction Stir-Welded Aluminum Alloy 1050

, which in literature are known as Burgers orientation relationships. The coherency of the two phases is controlled by this crystallographic mutual relationship. Loss of coherency between phases during deformation can originate from a non-parallelism between the two boundary crystallographic planes. This study focuses on αHCP/βBCC interface coherency evolution in a lamellar Ti–6Al–4V alloy subjected to hot compression at 800xa0°C. The strain rate was 10−3xa0s−1 and deformation was carried out to average true strains of εxa0=xa00.29, 0.69, and 1.20. Loss of coherency was found at strains εxa0≥xa00.50. For these strains, the lamellar αxa0+xa0β microstructure also evolved to a spheroidized morphology. The loss of interface coherency was thus associated with the acceleration of the lamellar microstructure dynamic spheroidization.

Development of grain structure during friction-stir welding of Cu–30Zn brass

High-resolution electron-backscatter diffraction was used to study the effect of welding temperature on the microstructure, texture, and strength of friction-stir welded aluminum. In all cases, the grain structure development was shown to be primarily governed by continuous recrystallization, although discontinuous recrystallization may also play a role at relatively high temperatures. An increase in welding temperature was shown to lead to transformation of the morphology of the deformation-induced substructure from lamellar type to equiaxed type. This was deduced to alter strain compatibility requirements and thus change the texture from

Evaluation of heat input during friction stir welding of aluminium alloys

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