Factsheet for CustomersSamples for Material Testing and Failure Analysis

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INFORMATION ABOUT THE SAMPLES

The more, the better: For the processing of questions

concerning material tests and failure analysis, it is

helpful if you provide us with as much information as

possible. The following checklist will help you with the

compilation.

Are you interested in:

Material Tests

> Material description

> Manufacturing process

> Coated or uncoated

> Coating process

> New or used part

> Verifi able target values for microstructure, hardness,

Chemical composition, tensile strength etc..

> Design drawing of the component

Failure Analysis

> Where did the failure occur?

> How often did this failure occur? Did it occur to

similar components?

> Type of load: e.g. sudden, shock-like load or oscillating

load? Corrosive or abrasive media? Overheating?

> Has the failure occurred or does it occur more fre-

quently in a certain production batch?

> For comparison, are there any components that have

survived the same load without failure?

> Were there any changes in your own or external

(e.g. supplier) process or production sequences?

Factsheet for CustomersSamples for Material Testing and Failure Analysis

Briefpapier Drucker – Seite 1 – Logo 4c

Factsheet for CustomersSamples for Material Testing and Failure Analysis

DEALING WITH SAMPLES

The improper handling of samples of damaged compo-

nents can lead to the fact that a statement about the

cause of damage is no longer possible.

In the following we will show you examples of „dama-

ged damages“ and fi nally give you some hints on how to

avoid them.

Fractured surfaces

Fractured surfaces can be severely damaged by contact.

In the worst case, the fracture surfaces can no longer be

evaluated. If, for example, several parts are packed

together, the fracture surfaces can be destroyed by the

relative movements of the individual parts (e.g. steel on

steel).

Contaminations

Hand contact can damage the delicate fi ne structures of

the fracture surface. They also leave residues on the

specimens (fi nger sweat, skin cells). These cover the

surface to be examined and falsify the result of an EDX

analysis of the chemical composition of the sample.

WORN FRACTURE SURFACES ON A SCREW

UNDAMAGED AND WORN FRACTURE SURFACES

20 µm 20 µm

300 µm

UNDAMAGEDFRACTURE SURFACE

WORN-OUT FRACTURE SURFACE

RESIDUE ON THE SAMPLE SURFACE

SKIN FLAKES ON THE SAMPLE SURFACE

100 µm 100 µm 100 µm 100 µm

10 µm

FINGERPRINT IN THE SCANNING ELECTRON MICROSCOPE (SEM)

100 µm

Briefpapier Drucker – Seite 1 – Logo 4c

Factsheet for CustomersSamples for Material Testing and Failure Analysis

Sample Storage

Incorrect sample storage before shipping may also im-

pair the evaluability. For example, storage in a humid

environment often leads to corrosion that can mask or

even destroy the original damage.

Hydrogen Analysis

For the examination of samples with suspected hydro-

gen embrittlement, it should be noted that the hydro-

gen may diff use out of the sample material after the

damage has occurred. A chemical analysis then shows a

hydrogen content that is lower than the actual amount

of hydrogen present at the time of the damage. The ear-

lier an analysis is carried out after the damage has oc-

curred, the better.

Cutting of samples

When cutting, especially when cutting without coolant,

microstructural changes can occur due to strong

heating or mechanical deformation. The sample can

soften or harden and thus infl uence the result of a hard-

ness measurement. In turn, coolants leave residues on

the sample that interfere with the SEM examination.

Ideally, you should have the sample separated directly

by us. Heating the sample also promotes the diff usion of

hydrogen.

Briefpapier Drucker – Seite 1 – Logo 4c

Factsheet for CustomersSamples for Material Testing and Failure Analysis

NOTES ON SAFE SAMPLING

> Pack the samples safely as soon as possible after the failure has occurred

> Dismantle any damaged parts professionally

> Do not join fragments or fractured surfaces together

> Do not touch fractured surfaces

> Handle samples with gloves

> Pack samples in such a way that they are not exposed to abrasion

> Pack each sample piece in its own suitable sample packaging, e.g. LDPE bag with pressure strip closure

> Clearly label samples on the packaging

> Do not oil samples subsequently to protect them from corrosion

> Do not remove existing corrosion products

> Protect samples from heat

> Store dry

Further information on our services and failure analysis

can be found at www.fem-online.de

fem | Forschungsinstitut Edelmetalle + Metallchemie Katharinenstrasse 17 | 73525 Schwäbisch Gmünd | GermanyT +49 7171 1006-0 | F +49 7171 1006-900 info@fem-online.de | www.fem-online.de