Microstructure evolution and mechanical properties of 316H weld metal during aging

ABSTRACT

A standard 316H welding wire was used to obtain 6% δ-ferrite in the weld metal by the automatic tungsten inert gas welding. The effect of aging time at 750°C on microstructure and mechanical properties of the weld metal were analysed. The results showed that as the aging time increased, the δ-ferrite fraction decreased, and finally, δ-ferrite was no longer seen, the M₂₃C₆ fraction first increased and then decreased, and the σ phase fraction increased. Finally, the fractions of M₂₃C₆ and σ phase kept stable, but the size increased. Accordingly, as the aging time increased, the yield and tensile strengths first decreased significantly, then increased obviously and finally decreased slightly again, while the elongation and impact energy decreased all the time.

KEYWORDS:

• Tungsten inert gas welding
• aging treatment
• δ-ferrite
• M₂₃C₆
• σ phase
• mechanical property

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors are grateful for the financial support from the Opening Foundation of Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences under grant number 2019NMSAKF04 and China Institute of Atomic Energy under grant number 2016-DGB-I-KYSC-0024.