Date of Award

Summer 2003

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Mechanical Engineering

Committee Director

Keith M. Williamson

Committee Member

Stephen G. Cupschalk

Committee Member

Ravindra P. Joshi

Call Number for Print

Special Collections; LD4331.E56 M34 2003

Abstract

Although fusion welding techniques are well established, recent developments in solid state joining techniques have produced high quality welds in materials that are difficult to fusion weld. Friction Stir Welding (FSW) was developed in 1991 as a robust solid-state joining technique that uses a specially shaped rotating tool to generate heat and plasticize material around the tool. The tool then mixes plasticized material along the joint line to produce the weld. Over the last decade, FSW has become increasingly popular for welding aluminum. The combination of attractive properties of the weld and cost-efficiency has led researchers to investigate the feasibility of using FSW for steel. One of the major impediments for stir welding harder materials like steel is tool wear. This thesis proposes a novel thermomechanical hot channel (THC) technique for reducing tool wear and presents an analytical model to explain how the THC approach reduces the amount of work done by the tool in generating heat. In the proposed model, the THC processing temperature is approximately 1000oC, which is close to the temperature required for stir welding steel. In some cases, THCs could create some melting ahead of the tool, resulting in the formation of minor holes or pits. FSW experiments presented in this thesis suggest that these THC defects up to 0.125 times the nib diameter can be resolved without compromising the quality of the stir weld.

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DOI

10.25777/8vvb-fd88

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