Engine Titanium Consortium - Center for Nondestructive Evaluation ...

findings for the first billet studied, the coupon manufacturing procedure will be refined as necessary
for subsequent billets and forgings.
Synthetic Inclusion Samples: Synthetic inclusions will be embedded into Ni test standards for the
purpose of evaluating the inspection sensitivity of ultrasonics on melt-related defects. The team will
review the findings from the metallurgical analysis on the naturally occurring defects to identify the
candidate inclusion types for sample manufacture. Construction methods will be developed at
GE-CRD to chemically manufacture the synthetic inclusions and to embed the inclusions into Ni
alloy test blocks. After the successful development of synthetic inclusion manufacturing methods,
three blocks containing synthetic inclusions of different geometry and composition will be
manufactured. The types of inclusions will be determined by the team based on the ability to
manufacture the synthetic inclusions, the criticality of the defect to part life, and the sensitivity of the
inspection to the composition and geometry of the defect type.
The team will ultrasonically evaluate the synthetic inclusion samples to determine the sensitivity of
the inspections for detecting and characterizing melt-related defects. This data will be used for the
validation of computer-based flaw models and for the generation of POD curves for Ni alloy billets.
Defect Characterization: Samples will also be acquired with real defects potentially to include dirty
white spots, segregation (freckles), and slag (from ESR), reflecting both VIM/VAR and
VIM/ESR/VAR material defects in 718 and Waspaloy. The initial effort will focus on evaluation of
natural defects to establish typical compositions and properties and their detectability. Six samples
will be evaluated using a limited ultrasonic characterization and a simplified metallographic process.
Ultrasonic measurements will be performed at two stages:
• original samples prior to sectioning
• defects machined to regular shapes
Characterization data will be used to optimize the inspection development efforts of 1.1.2, provide
data for validation of flaw models and provide input for generation of POD for nickel billet in 3.1.1.
Results will be included in the final report.
Objective/Approach Amendments: Objective and approach remain as originally proposed in July
1998.
Progress (January 1, 2002 – March 31, 2002):
Several consortium conference calls were conducted during the quarter to discuss the details of the
subtask. A number of technical issues were discussed and decisions reached. The technical
issues and discussions are summarized into two primary areas, (1) Property Measurements, and
(2) Metallographic Microstructure which are discussed separately below.
Property Measurements
A primary goal of the Ni billet Fundamental Studies subtask is to determine, for representative Nialloy
billets, the manner in which ultrasonic properties depend on inspection direction and position
within the billet. The inspection properties of interest are the sonic velocity, attenuation, and
backscattered grain noise level, with the latter two properties strongly dependent on the inspection
frequency. Results of the property measurements will later be used by the Production and
Quarterly Report – January 1, 2002 –March 31, 2002
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