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Failure Analysis of Resistance Spot Welded Advanced High Strength Steel Sheets
전기 저항 용접한 초고강도강판의 파손 거동 분석

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Authors
노우람
Advisor
정관수
Major
공과대학 재료공학부
Issue Date
2015-02
Publisher
서울대학교 대학원
Keywords
Advanced high strength steel sheetResistance spot weldingSimilar/Dissimilar weldsFracture criterionHardening deterioration
Description
학위논문 (박사)-- 서울대학교 대학원 : 재료공학부, 2015. 2. 정관수.
Abstract
A method to analyze the failure (fracture) behavior of resistance spot welded joints was developed in this work, which was applied for the similar welds and the dissimilar welds of advanced high strength steel sheets. As for the similar welds, TRIP980 and DP980 sheets were analyzed along with a conventional mild steel sheet (GMW2) for comparison purpose. Based on the TRIP980 sheet, as for the dissimilar welds, one was fabricated with the DP980 sheet (DP980-TRIP980) and the other with a conventional mild steel sheet GMW2 (GMW2-TRIP980). The method included the characterization of base material sheets regarding hardening data and fracture criteria mainly based on the inverse numerical analysis of uniaxial tension tests. Besides, hardness measurement across the cross-section of the weld nugget along with optical microscopic observation was utilized to identify the shapes and dimensions of the base, heat-affected zone, and the fusion zone. Utilizing their geometric features, their fracture criteria as well as mechanical properties were characterized based on the inverse numerical analysis of a newly designed miniature tension test. Ultimately, the characterized properties of the base materials and the weld zones were applied to analyze the failure (mode and strength) in the coupon tests of lap-shear and U-shape tension tests for welded sheets (also, as an effort to validate the calibrated properties). All analysis was performed under the quasi-static condition in this work.
Language
English
URI
https://hdl.handle.net/10371/117992
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Materials Science and Engineering (재료공학부)Theses (Ph.D. / Sc.D._재료공학부)
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