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Evolution of microstructure and residual stress under various vibration modes in 304 stainless steel welds.

Hsieh CC, Wang PS, Wang JS, Wu W - ScientificWorldJournal (2014)

Bottom Line: The experimental results indicate that the temperature gradient can be increased, accelerating nucleation and causing grain refinement during this process.A residual stress can obviously be increased, producing an excellent effect on stress relief at a resonant frequency.The stress relief effect with an eccentric circulating vibrator was better than that obtained using a magnetic telescopic vibrator.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 402, Taiwan.

ABSTRACT
Simultaneous vibration welding of 304 stainless steel was carried out with an eccentric circulating vibrator and a magnetic telescopic vibrator at subresonant (362 Hz and 59.3 Hz) and resonant (376 Hz and 60.9 Hz) frequencies. The experimental results indicate that the temperature gradient can be increased, accelerating nucleation and causing grain refinement during this process. During simultaneous vibration welding primary δ -ferrite can be refined and the morphologies of retained δ-ferrite become discontinuous so that δ-ferrite contents decrease. The smallest content of δ-ferrite (5.5%) occurred using the eccentric circulating vibrator. The diffraction intensities decreased and the FWHM widened with both vibration and no vibration. A residual stress can obviously be increased, producing an excellent effect on stress relief at a resonant frequency. The stress relief effect with an eccentric circulating vibrator was better than that obtained using a magnetic telescopic vibrator.

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The Fe-Cr-Ni phase diagram.
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fig12: The Fe-Cr-Ni phase diagram.

Mentions: Figures 11(a)–11(e) show the morphologies of δ-ferrite with various vibration modes. The parts of dark and light were the δ-ferrite and γ-austenite, respectively. The δ-ferrite indicated two morphologies of the lathy and the vermicular. However, the solidification path is as follows: L → (L + δ)→(L + δ + γ)→(δ + γ)→(γ) in the AISI 304 stainless steels. The vibration welding can affect the diffusion of liquid atoms, but it can also affect the δ → γ phase transformation subsequent cooling. Because the δ → γ phase transformation occurs above 1400°C, as shown in Figure 12 [14]. Hence, the δ → γ solid phase transformation will occur during solidification. The δ-ferrite was a primary phase and the δ → γ phase transformation occurs because of the diffusion of Cr and Ni [15]. Therefore, the morphology of the residual δ-ferrite was affected by that of the primary δ-ferrite.


Evolution of microstructure and residual stress under various vibration modes in 304 stainless steel welds.

Hsieh CC, Wang PS, Wang JS, Wu W - ScientificWorldJournal (2014)

The Fe-Cr-Ni phase diagram.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3926365&req=5

fig12: The Fe-Cr-Ni phase diagram.
Mentions: Figures 11(a)–11(e) show the morphologies of δ-ferrite with various vibration modes. The parts of dark and light were the δ-ferrite and γ-austenite, respectively. The δ-ferrite indicated two morphologies of the lathy and the vermicular. However, the solidification path is as follows: L → (L + δ)→(L + δ + γ)→(δ + γ)→(γ) in the AISI 304 stainless steels. The vibration welding can affect the diffusion of liquid atoms, but it can also affect the δ → γ phase transformation subsequent cooling. Because the δ → γ phase transformation occurs above 1400°C, as shown in Figure 12 [14]. Hence, the δ → γ solid phase transformation will occur during solidification. The δ-ferrite was a primary phase and the δ → γ phase transformation occurs because of the diffusion of Cr and Ni [15]. Therefore, the morphology of the residual δ-ferrite was affected by that of the primary δ-ferrite.

Bottom Line: The experimental results indicate that the temperature gradient can be increased, accelerating nucleation and causing grain refinement during this process.A residual stress can obviously be increased, producing an excellent effect on stress relief at a resonant frequency.The stress relief effect with an eccentric circulating vibrator was better than that obtained using a magnetic telescopic vibrator.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 402, Taiwan.

ABSTRACT
Simultaneous vibration welding of 304 stainless steel was carried out with an eccentric circulating vibrator and a magnetic telescopic vibrator at subresonant (362 Hz and 59.3 Hz) and resonant (376 Hz and 60.9 Hz) frequencies. The experimental results indicate that the temperature gradient can be increased, accelerating nucleation and causing grain refinement during this process. During simultaneous vibration welding primary δ -ferrite can be refined and the morphologies of retained δ-ferrite become discontinuous so that δ-ferrite contents decrease. The smallest content of δ-ferrite (5.5%) occurred using the eccentric circulating vibrator. The diffraction intensities decreased and the FWHM widened with both vibration and no vibration. A residual stress can obviously be increased, producing an excellent effect on stress relief at a resonant frequency. The stress relief effect with an eccentric circulating vibrator was better than that obtained using a magnetic telescopic vibrator.

Show MeSH