Session: 18-07: Failure Prediction and Life Asssessment II

Submission Number: 175685

Investigation of the High-Cycle-Fatigue Characteristics of LPBF 5083 Aluminum Alloy 

The objective of this study is to assess the high-cycle-fatigue characteristics of aluminum alloy 5083 fabricated by laser powder bed fusion (LPBF). Aluminum alloy 5083 is a high-strength alloy that displays good printability and corrosion resistance. Additive manufacturing (AM) processes, such as LPBF, offer the ability to quickly manufacture complex geometries for fast prototyping and are sought after as an option for jet engine components. However, AM materials exhibit worse tensile properties and fatigue resistance when compared to wrought materials. This is due to AM build defects and differences in the microstructure. The microstructure of LPBF hosts columnar grains while wrought 5083 is more equiaxed.

In this study, the tensile and high-cycle-fatigue resistance of LPBF aluminum alloy 5083 is evaluated. The calculated stress-strain curve and hardness are measured using indentation plastometry. The tensile properties are verified via ASTM E8 tension testing. The differences between indentation plastometry and tension properties are assessed. Load-controlled high-cycle fatigue tests are performed at stress ratios, R of 0.1 and -1.0 respectively. Crack initiation, propagation, and fast fracture sites are examined via optical microscopy and evaluated as function of stress amplitude and ratio. A stress-life curve is generated, and the effect of mean stress is analyzed with the Smith-Watson-Topper (SWT) and Walker mean stress corrections applied to the Basquin equation to obtain fatigue life predictions and properties. The AM tension and fatigue properties are compared to conventional 5083 alloy data obtained from literature. The fatigue resistance of LPBF and wrought 5083 are compared by evaluating the Basquin material constants and calculated endurance limit at 5∙10^8 cycles to determine the LPBF knock down factor. The knock down factor can be used to strategically redesign jet engine components to account for the loss in fatigue resistance in the LPBF form, modify engine operating conditions, adjust the maintenance schedule to maintain reliability.

Presenting Author: Malcolm Pierce Ohio State University

Presenting Author Biography: Malcolm Pierce is a third-year undergraduate student at The Ohio State University studying mechanical engineering. Malcolm is an undergraduate research assistant in the Materials at Extremes (MATX) Laboratory, which focuses on advanced manufacturing, testing & characterization, and theoretical mechanics of materials subject to thermal, mechanical, and chemical extremes. His current research involves the testing and characterization of additively manufactured aerospace materials to uncover fatigue properties.

Authors:

Malcolm Pierce Ohio State University
Onome Scott-Emuakpor Hyphen Innovations
Philip Johnson Hyphen Innovations
Calvin Stewart Ohio State University