Mechanical Properties of Friction Stir Welded Ni-Base Superalloy

Abstract

This study was carried out to evaluate the microstructures and mechanical properties of a friction stir welded Ni based alloy. Inconel 600 (single phase type) alloy was selected as an experimental material. For this material, friction stir welding (FSW) was performed at a constant tool rotation speed of 400 rpm and a welding speed of 150~200 mm/min by a FSW machine, and argon shielding gas was utilized to prevent surface oxidation of the weld material. At all conditions, sound friction stir welds without any weld defects were obtained. The electron back-scattered diffraction (EBSD) method was used to analyze the grain boundary character distributions (GBCDs) of the welds. As a result, dynamic recrystallization was observed at all conditions. In addition, grain refinement was achieved in the stir zone, gradually accelerating from 19 µm in average grain size of the base material to 5.5 µm (150 mm/min) and 4.1 µm (200 mm/min) in the stir zone with increasing welding speed. Grain refinement also led to enhancement of the mechanical properties: the 200 mm/min friction stir welded zone showed 25% higher microhardness and 15% higher tensile strength relative to the base material.

Evaluation of Microstructure and Mechanical Properties of Friction Stir Lap Jointed Inconel 600/SS 400

“…[3][4][5] 최근, 이러한 문 제점들을 해결하기 위해, 니켈기 초합금에 대한 마찰교 반접합의 기초연구가 다양하게 수행되어 왔는데, 그 결 과, 마찰교반접합의 적용은 미세조직제어와 기계적 물성 의 향상에 효과적인 것으로 보고된 바 있다. [6][7][8][9][10] 간의 적층결함에너지(< 100 mJ/m 2 )를 갖는 재료이다. 14) 이 러한 재료는 동적회복에 의한 전위의 재배열이 어렵기 때 문에, 동시 다발적인 재결정 핵생성에 더욱 유리한 조건 을 갖고 있다.…”