Low Cycle Fatigue Properties of 316LN Stainless Steel Welded by GTAW in Nitrogen Added Environment

Abstract:

Tensile and fatigue properties were evaluated for base and welded type 316LN stainless steel. Welding methods were GTAW (308L, Ar environment) and GTAWN (316L, Ar + N2 environment). Yield strength of weld joint was higher than that of base metal but elongation of weld joint was lower than that of base metal. UTS of weld joint was slightly lower than that of base metal. Yield strength and elongation with welding method were almost same. Fatigue life of weld joint was lower than that of base metal but fatigue strength of weld joint was higher than that of base metal. Ferrite content was increased with welding. Fatigue life welded by GTAWN was better than that of GTAW at RT and 600°C. This fatigue life behavior was consistent with the behavior of ferrite content.

• Periodical: Key Engineering Materials (Volumes 345-346)
• Pages: 275-278
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.345-346.275
• Online since: August 2007
• Authors: Dae Whan Kim, Chang Hee Han, Woo Seog Ryu
• Keywords: Fatigue, GTA Welding, Stainless Steel (SS), Welding

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200 400 600 800.

200 400 600 Yield stress, MPa Temperature, o C Base GTAW GTAWN.

200 400 600 800.

200 400 600 800 UTS, MPa Temperature, oC Base GTAW GTAWN.

200 400 600 800.

[20] [40] [60] Elongation, % Temperature, o C Base GTAW GTAWN Fig. 1. Tensile properties for base and welded 316LN stainless steel.

1 2 3 4.

[20] [40] [60] [80] Stress drop, MPa Displacement, mm Base GTAW GTAWN 600oC Fig. 2. Stress relaxation at 600℃ and 10 min. holding for base and welded 316LN stainless steel.

[1] [2] [10] [2] 103.

[10] [4] Cycles to failure Total strain range, % Base GTAW GTAWN R. T 1.

[2] [10] [3] 104 Cycles to failure Total strain range, % Base GTAW GTAWN 300o C.

[1] [2] [10] [2] 103 104 Cycles to failure Total strain range, % Base GTAW GTAWN 600 oC Fig. 3. Low cycle fatigue lives with temperature for base and welded 316LN stainless steel.

[10] [0] 101 102 103 104.

100 200 300 400 500 600 Tensile peak stress, MPa Cycles to failure Base GTAW GTAWN RT, 1.

[10] [0] [10] [1] [10] [2] [10] [3] [10] [4] [0] 100 200 300 400 500 Tensile peak stress, MPa Cycles to failure Base GTAW GTAWN 300 o C, 1% 100 101.

[10] [2] 103 104.

100 200 300 400 500 Tensile peak stress, MPa Cycles to failure Base GTAW GTAWN 600o C, 1% Fig. 4. Tensile peak stress with cycles with temperature for base and welded 316LN stainless steel Before test 0. 8% 1. 0% 1. 5% -0.

[5] [10] [15] [20] [25] [30] Ferrite content, % Strain range, % GTAW GTAWN RT Before test 0. 8% 1. 0% 1. 5% -0.

[5] [10] [15] [20] Ferrite content, % Strain range, % GTAW GTAWN 300o C Before test 0. 8% 1. 0% 1. 5% -0.

[5] [10] [15] [20] Ferrite content, % Strain range, % GTAW GTAWN 600 oC Fig. 5. Ferrite contents before and after fatigue test for welded 316LN stainless steel.