INVESTIGATIVE SUMMARY Cardwell Westinghouse Report No.: 237863A 433 West 83rd St Date: 9/21/2015 Chicago, IL 60620 Order No.: 101336 Page: 1 of 5 Attention: Mr. Shaun Whalen

Supplement to SGS MSi Report 237863: Additional material specification provided by Client.

BACKGROUND

One (1) fractured side bearing cage was submitted to our laboratory for a metallurgical investigation. The part reportedly failed in the field after approximately two years of service. The material was identified as austempered ductile iron (ADI) per the client material specification SK-3086. No further background information was available. We were requested to determine the nature of the failure and verify the grade and chemical composition.

SAMPLE IDENTIFICATION

Client ID Part Description Client Specification Material

TST-0265 SBX-45 Side Bearing Cage (Housing) SK-3086 ADI

PERFORMED TESTING

Visual and Stereoscopic Examination Metallographic (Microstructural) Examination Chemical Testing Tensile Testing Charpy Impact Testing Hardness Testing

CONCLUSIONS

1. Based upon the performed tests, examinations and supplied background information, it is our opinion the cage failed due to a single-event brittle overload. No evidence was observed of any pre-existing defects or detrimental microstructural conditions that could have contributed to the failure.

2. Visual examination of the fracture surfaces revealed a flat, dull and fibrous appearance with no

evidence of a progressive fatigue failure mechanism. Stereoscopic examination revealed a radial pattern originating from the inner surface at the base of the cage, which was identified as the fracture initiation site. No evidence was observed of any pre-existing casting defects that could have contributed to the failure. The overall fracture features were characteristic of a single-event brittle overload fracture.

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CONCLUSIONS (cont.) 3. Metallographic examination indicated the fracture exhibited a mixed mode of intergranular and

transgranular crack propagation through the entire thickness, typical of rapid overload. No evidence was observed of any pre-existing casting defects or detrimental microstructural condition, such as graphite degradation, at the ID surface that could have contributed to the failure.

4. The observed microstructure and the chemical, tensile, Charpy impact and hardness test results

conformed to the client specified minimum requirements of SK-3086.

SUMMARY of TEST RESULTS

Visual and Stereoscopic Examination

1. The submitted cage was received with a dual fracture originating from the base of the cage at the lug slot (see Photo 1). A section of the cage fractured away and was not available for examination. The fracture surfaces were heavily oxidized and rusted. The fracture surfaces were ultrasonically cleaned in a slightly alkaline (soap) solution for further examination.

2. Visual examination after cleaning revealed both fracture surfaces exhibited a flat, dull and fibrous

appearance with no evidence of a progressive fatigue failure mechanism. Stereoscopic examination revealed a radial pattern originating from the inner surface at the base of the cage (see Photo 2). No evidence was observed of any pre-existing casting defects that could have contributed to the failure. The overall fracture features were characteristic of a single-event brittle overload fracture.

Photo 1: As-received cage showing dual fractures originating from the ID surface at the base (arrows)

Photo 2: Exposed fracture surface showing the cracking originated from the ID surface. Magnification: 7X

ID Surface

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Metallographic Examination

1. A cross section through one of the fractures was removed and prepared for metallographic examination.

2. Metallographic examination indicated the fracture exhibited a mixed mode of intergranular and

transgranular crack propagation through the entire thickness, typical of rapid overload (see Photos 3 and 4). No evidence was observed of any pre-existing casting defects or detrimental microstructural conditions, such as graphite degradation, at the ID surface.

3. Examination of the sample in the unetched condition revealed a uniform distribution of nodular

graphite (see Photo 5). The graphite nodularity, nodule count, form type and size were rated in accordance with ASTM 247, Plates I and III with the following results:

Sample ID % Nodularity Nodule Count/mm2 Graphite Form Size Class

SB Cage 90% 125 Type 1 / 2 5 / 6

4. Examination of the sample in the etched condition revealed a typical ADI microstructure consisting of acicular ferrite and austenite with less then 2% carbide (see Photo 6).

Photo 3: Magnification: 100X; Etchant: 3% Nital Photo 4: Magnification: 100X; Etchant: 3% Nital Fracture at the ID surface (right of Photo).

Cracking propagated both intergranularly and transgranularly through the wall thickness of the cage

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Metallographic Examination (cont.)

Photo 5: Magnification: 100X; Etchant: None Photo 6: Magnification: 500X; Etchant: 3% Nital

SB Cage - Nodular Graphite Morphology. SB Cage - Representative microstructure.

Chemical Testing

1. The chemical test results are shown in Table 1 below.

Table 1 - Chemical Testing*

Element SB Cage

Carbon 3.73 %

Manganese .44

Phosphorus .021

Sulfur .014

Silicon 2.16

Nickel <.01

Chromium .05

Molybdenum <.01

Copper <.01

Magnesium .04

* Carbon and Sulfur analysis performed in accordance with ASTM E1019. Other elements determined by optical spectrometer in accordance with ASTM E415.

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Tensile Testing

1. Tensile test results conformed to the specified minimum tensile requirements per SK-3086.

2. The tensile testing results are shown in Table 2 below.

Table 2 - Tensile Testing*

SB Cage SK-3086

Tensile Strength, ksi 182 175 min.

Yield Strength, ksi (.2% offset) 146 125 min.

% Elongation in 1” (4D) 3 2% min.

∗ Testing performed in accordance with ASTM A370 and E8.

Charpy Impact Testing

1. The average of the Charpy impact test results (21 ft-lbs) for the cage conformed to the specified minimum requirement of 15 ft-lbs per SK-3086.

2. The results are shown in Table 3 below.

Table 3 - Charpy Impact Testing*

Test Temperature: Specimen Size: Notch Type:

+ 72°F 10 x 10 mm

None

Sample Absorbed Energy, ft-lbs Average, ft-lbs** SB Cage 14 18 22 22 21

* Testing performed in accordance with ASTM E23 using a digitally encoded 700 ft-lb impact tester.

** Average of three highest values.

Hardness Testing 1. The Brinell hardness of the cage measured 415 HBW, which fell into the typical hardness range

of 344 – 441 HBW per SK-3086. Prepared By: Frank Guerrieri, Staff Metallurgical Engineer Reviewed By: John J. Fruscione, Senior Metallurgical Engineer