Mechanical Behaviour of SS 316 (N) Weld after Long Term Exposure to Service Temperatures

The Influence of Corrosion on the Mechanical Behavior of AISI 316L Stainless Steel Welds

“…A certain quantity of δ-ferrite is useful for the welded austenitic stainless steels. 3-7 Vol.% of the δ-ferrite formed in austenite matrix acts to inhibit hot cracks during solidification [7,8]. In addition, it is known that δ-ferrite contains higher Cr than the austenitic structure.…”

Influence of Aging Treatment on the Microstructure Evolution and Mechanical Properties of 316H Weld Metals with Different C Contents

“…Shitong WEI, 1) Langlang ZHAO, 2,3) Dong WU, 3) Dianbao GAO 4) and Shanping LU 3 The influence of 600°C aging treatment on the microstructure and mechanical properties of 316H stainless steel weld metals with different C contents have been studied. The results indicated that during the aging process, the rapid precipitation of M 23 C 6 carbide occurred in δ -ferrite firstly owing to the high diffusion rate of C. After the C is depleted by precipitation of M 23 C 6 , the residual δ -ferrite transforms into σ phase through eutectoid transformation (δ -ferrite → σ phase + γ ).…”

“…In addition, these critical components are not replaceable during their service life. 1,2) The feedback experience of the in-service inspection for nuclear power plant shows that many problems are caused by the failure of welded joints, and many factors affect the quality of welded joints. [3][4][5][6] The performance of joints is not only related to the mechanical properties and weldability of base metals, but also to the properties of weld metal and welding processes.…”

“…[13][14][15][16][17][18][19][20][21][22] At present, there is still much controversy about the precipitation mechanisms of carbides and intermetallic phases in the austenitic stainless steel weld metal and the decomposition mechanism of δ -ferrite during the aging process. 2,5,6,[23][24][25][26][27][28][29] Rhouma et al 23) conducted the phase identification of the 316 L austenitic stainless steel with a small amount of δ -ferrite aged for up to 80 000 hours at the temperature range of 550-700°C. They found that the δ -ferrite decomposed gradually into M 23 C 6 at 550°C and decomposed totally into intermetallic phases (σ, η, χ, and R) and into secondary austenite (γ ) at the temperatures equal to or higher than 650°C.…”

“…The depletion of Cr and Mo caused by the precipitation of M 23 C 6 resulted in the slow transformation of δ -ferrite in high C 316 weld metal. Dutt et al 2) analyzed the mechanical properties of the 316L stainless steel weld after long term aging treatment. They found that both impact energy and J-R curves decreased after aging at 370, 475 and 550°C, and variations of the mechanical properties were related to the transformation of the δ -ferrite during aging process.…”