Location

Snowbird, UT, USA

Start Date

1-1-1999 12:00 AM

Description

The use of titanium—hot isostatic pressed (HIP) castings in damage tolerant aircraft structures requires not only a new approach in design philosophy and manufacturing methods, but also new methods and data for assuring structural integrity by nondestructive inspection methods. The use of large titanium castings (Fig. 1) in components that have been traditionally forged offers potential for reduction of aircraft weight, increases in structural stiffness, more uniform material properties, greater geometric complexity, reduced production cost, and reduced production lead time. Castings are produced by the investment casting process in which a ceramic coating (termed “facecoat”) is applied to a wax shape and is reinforced by the addition of a secondary coating (termed “stucco”). During the casting process, the facecoat (and sometimes stucco) may spall and be incorporated into the casting as a ceramic inclusion (termed “shell”). Casting component designs must therefor include acceptance criteria for shell inclusions in assuring damage tolerance in structural integrity of the component [1]. The lower limit of acceptance criteria is often based on the detection capabilities of applied nondestructive inspection procedures [2,3]. Each casting vendor uses a “proprietary” facecoat / stucco formulation and process, thus the detectability of the shell inclusions may vary with each vendor. Facecoat typically consists of three to five layers applied directly to the wax pattern. In addition, the anomaly size that must be used in design analysis, must include the affected area around the inclusion (termed the “halo”), as shown in Fig. 2, and is not the detected size that can be discriminated by nondestructive inspection procedures.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

18B

Chapter

Chapter 8: Process Control, Reliability, and Training

Section

NDE Reliability Calibration

Pages

2311-2317

DOI

10.1007/978-1-4615-4791-4_296

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Quantitative Assessment of the Detectability of Ceramic Inclusions in Structural Titanium Castings by X-Radiography

Snowbird, UT, USA

The use of titanium—hot isostatic pressed (HIP) castings in damage tolerant aircraft structures requires not only a new approach in design philosophy and manufacturing methods, but also new methods and data for assuring structural integrity by nondestructive inspection methods. The use of large titanium castings (Fig. 1) in components that have been traditionally forged offers potential for reduction of aircraft weight, increases in structural stiffness, more uniform material properties, greater geometric complexity, reduced production cost, and reduced production lead time. Castings are produced by the investment casting process in which a ceramic coating (termed “facecoat”) is applied to a wax shape and is reinforced by the addition of a secondary coating (termed “stucco”). During the casting process, the facecoat (and sometimes stucco) may spall and be incorporated into the casting as a ceramic inclusion (termed “shell”). Casting component designs must therefor include acceptance criteria for shell inclusions in assuring damage tolerance in structural integrity of the component [1]. The lower limit of acceptance criteria is often based on the detection capabilities of applied nondestructive inspection procedures [2,3]. Each casting vendor uses a “proprietary” facecoat / stucco formulation and process, thus the detectability of the shell inclusions may vary with each vendor. Facecoat typically consists of three to five layers applied directly to the wax pattern. In addition, the anomaly size that must be used in design analysis, must include the affected area around the inclusion (termed the “halo”), as shown in Fig. 2, and is not the detected size that can be discriminated by nondestructive inspection procedures.