Fatigue strength improvement of stainless steel using weld toes dressing with low transformation temperature welding wire

Abstract

In the present study, low transformation temperature welding wire (LTTW), which can induce residual compressive stress around 304L welded joints, has been developed to improve the fatigue performance of welded joints. Procedure of design and chemical composition of weld metal and deposited metal of LTTW are introduced. The microstructure of weld metal of LTTW is composed of low carbon martensite and residual austenite. The residual stress distribution of a single welding bead of LTTW was measured and the result shows that compressive residual stress is generated. In addition, fatigue test was also carried out on no-load cruciform welded joints of 304L stainless steel under three conditions: as welded, 308L dressing and LTTW dressing. The result shows that the fatigue life of LTTW dressing joints (2×10⁶ cycles) is improved by 14–23 times and 3–6 times compared with that of as welded joints and 308L dressing joints.

Keywords:

• Low transformation temperature welding wire
• Stainless steel
• Compressive residual stress
• Fatigue strength

Acknowledgements

The present research work was financially supported by the Project of the National Natural Science Foundation of China (Grant No. 51275341), the Research Fund for the Doctoral Program of Higher Education of China (20130032110005) and Promote the Ocean by Science and Technology Project of Tianjin Oceanic Administration (KJXH2012-08).