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Effect of Preferential Vaporization during Laser Rewelding on the Solidification and Cracking Response of Type 304L Stainless Steel Alloys with Systematically Varied Manganese Contents

Berger, Jason E
http://rave.ohiolink.edu/etdc/view?acc_num=osu1523533179094721

Abstract Details

2018, Master of Science, Ohio State University, Welding Engineering.
Past research has correlated preferential vaporization during autogenous laser rewelding of Type 304L stainless steel with a shift from primary ferrite to primary austenite solidification and an increase in solidification cracking susceptibility. In the present study, custom Type 304L alloys with systematically varying levels of manganese and commercial Type 304L alloys were subjected to various reweld cycles to understand preferential element vaporization and the evolution in composition, solidification mode, and solidification cracking susceptibility during laser rewelding. Rewelding was performed using both continuous wave and pulsed laser operation and the welding process parameters were varied to determine the effect of welding parameters on the vaporization behavior of an alloy. A combination of traditional and advanced techniques were used to characterize the rewelded samples. In particular, bulk weld metal composition analysis was performed using arc-spark optical emission spectroscopy, and local composition analysis was performed using electron probe microanalysis. Characterization of solidification mode and microstructure was performed using light optical microscopy and scanning election microscopy techniques. It was shown that vaporization is a strong function of equilibrium vapor pressure and weld pool temperature and that preferential vaporization of given alloying elements from the weld pool is dependent on the volatility of the element and the activity of the element in the weld pool. The experimental results indicated that preferential vaporization results in a decrease in the chromium, manganese, and copper content and an increase in the nickel, silicon, and iron content of the weld metal relative to the base metal with successive rewelding. Further, preferential vaporization results in a decrease in the chromium-nickel equivalent ratio and a shift from primary ferrite solidification to primary austenite solidification when a critical composition is reached for fixed solidification conditions. Using the experimental results and a fundamental understanding of vaporization phenomena, optimized neural networks and a simplified analytical model were developed to predict the weld metal composition as a function of starting material composition, welding process parameters, and number of reweld passes. Both approaches demonstrated good performance compared to the experimental conditions tested in the study and serve as fast, easy-to-use engineering tools that may be implemented in a production environment to predict the evolution in composition, solidification mode, and cracking susceptibility of an alloy during laser rewelding.
Antonio Ramirez (Advisor)
Zhang Wei (Committee Member)
Engineering; Materials Science
Laser Welding; Type 304L; Stainless Steel; Vaporization; Rewelding

Recommended Citations

Citations

  • Berger, J. E. (2018). Effect of Preferential Vaporization during Laser Rewelding on the Solidification and Cracking Response of Type 304L Stainless Steel Alloys with Systematically Varied Manganese Contents [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523533179094721

    APA Style (7th edition)

  • Berger, Jason. Effect of Preferential Vaporization during Laser Rewelding on the Solidification and Cracking Response of Type 304L Stainless Steel Alloys with Systematically Varied Manganese Contents. 2018. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1523533179094721.

    MLA Style (8th edition)

  • Berger, Jason. "Effect of Preferential Vaporization during Laser Rewelding on the Solidification and Cracking Response of Type 304L Stainless Steel Alloys with Systematically Varied Manganese Contents." Master's thesis, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523533179094721

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.