Updates to Metals Standards2013

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Questions to Answer

• Which metals standards have changed recently?

• Why and how have the standards changed?

• How does it effect me?

• How do I ensure compliance with the latest standards?

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Product Standards Linked to Testing Standards

ISO 6892-1 2009

ASTM E8M:2013

ASTM A370

Standard Test Methods and Definitions for

Mechanical Testing of Steel Products

ANSI/API Spec 5L

Petroleum and natural gas industries

Steel pipe for pipeline transportation systems

ISO 3183:2012

Petroleum and natural gas Industries

Steel pipe for pipeline transportation systems

ISO 377:1997

Steel and steel products

Location and preparation of samples

and test pieces for mechanical testing

ISO 7438:2005

ASTM E290:2013

ANSI/API Spec 5L

ISO 3183:2012

ISO

148-1:2010

ASTM E-23

ANSI/API Spec 5L

ISO 3183:2012

Bend Testing

Charpy ImpactTesting

Tensile Testing

Example: Pipe and Tube Applications

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Evolution of Standards

ISO/EN Standards

EN 10002-1:2001

ISO 6892-1:2009

ASTM Standards

E8-04

E8M-04Separate standards

E8/E8M-11Combined standard

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• ISO 6892-1:2009• Added a Strain Rate method – commonly referred to as

“Method A”

• Separated Method A (strain rate)and Method B (stress rate)

• Various other small changes

• ASTM E8/E8M-11• The two separate standards have been combined into

one standard for imperial and metric

• Clarified testing speeds and added tolerances for strain rate

• Various other small changes

Significant Recent Changes

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Strain Rate• What is strain rate?

• Change in Specimen Length/Original Gauge Length/Time• Change in strain per unit of time (in/in/min, mm/mm/s, %/s, s-1)• Typically measured with an extensometer on metals specimens

• Why is this getting industry-wide attention now?• In 2009, the primary metals tensile testing standards were

updated to include more strict requirements for strain rates and more detailed guidance on how to achieve target strain rates

• ISO 6892-1:2009 superseded EN10002-1• Occurred at the end of 2009• Introduced control “Method A” based on maintaining strain rates

• ASTM E8/E8M–09 was updated to include straining rate method and guidance on proper test rate control

• Prior to this, strain rates were mostly found in product standards, such as aerospace (Nadcap/EN 2002)

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Why Strain Rate?

• Some metals have mechanical properties that are strain-rate dependant

• From ISO 6892-1“Method A is intended to minimize the variation of the test rates during the moment when strain rate sensitive parameters are determined and to minimize the measurement uncertainty of the test results.”

• From ASTM E8/E8M-11“The reproducibility of yield strength test results from machine to machine and laboratory to laboratory is good.”“In order to reproduce yield test results, for strain-rate sensitive materials, it is important that strain rates during the determination of yield are similar.”“The yield strength of some materials can change by more than ten percent when tested with the slowest and then the highest speeds permitted by E8/E8M.”

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Control Modes in ISO 6892-1 and ASTM E8MIS

O 6

892-

1:20

09

Method A – Closed Loop Strain Rate

Method A - Estimated Strain Rate

Method B – Stress Rate

AS

TM

E8M

-11

Method A – Rate of Stressing

Method B - Rate of Straining

Method C – Crosshead Speed Control

Strain control (Extensometer)

Stress control(load)

Extension control(crosshead)

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The Challenge with Strain Control

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System Compliance

Zero load Under load

Def

lect

ion

L o

Zero load

Lo +

ΔL

Under load

Compressed lead screw and drive system deflection

Load cell deflection

Crosshead and base deflection

Grip, jaw face and adaptor deflection

Amplified deflection!

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System Requirements

• Load frame• Precise and stable drive system

• Grips• Able to securely grip the specimen during the test

without slippage

• Extensometer• High-precision device with stable feedback

• Software/controller• Responsive control loop able to maintain ±20% or

±40% limits

• Lab environment• Vibration and shock free

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ISO 6892-1 Method A – Closed Loop ControlStrain Control Removes Compliance Effects

±20% Error Bounds

0.2% Offset Yield

Strain Control slows the crosshead down to compensate

Significant and rapid change in system stiffness during the onset of yield

Test being performed in closed loop strain control

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ISO 6892-1 Method A – Estimated Rate

Test being performed in extension control

±20% Error Bounds

Constant crosshead displacement

0.2% Offset Yield

Strain rate moves into ±20% error band during yield. Correct rate during Rp0.2 calculation point

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Why Instron® Customers use Strain Control

• Repeatable and comparable results• As some metals are strain-rate sensitive this reduces

variance between labs and systems

• Improved efficiency• Shorter testing times with a range of specimens

• Automatic tuning reduces setup time• No need to use a specimen for tuning

35% time savings when compared to estimated rate

ISO 6892-1 Method B – 10Mpa/s

ISO 6892-1 Method A – Estimated rate 0.00025/s

ISO 6892-1 Method A – Closed Loop rate 0.00025/s

Seconds

50 100

Time taken to run a ISO 6892-1:2009 test on Aluminium

0 25 75

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ISO 6982-1 or ASTM E8M – Closed Loop vs. Estimated RateSteel Specimen on a Rigid Load String

0 1 3 4 5 6 8 9 10111314151618192021232425272829303233343537383940424344454748495052535455575859616263646667680

100

200

300

400

500

600

700

Closed Loop Estimated Rate

Time (s)

Te

ns

ile S

tre

ss

(M

Pa

)

40% time savings when compared to estimated rate

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Which Systems Meet ISO 6892-1?

ISO 6892-1:2009

Method A

Strain Rate

Closed Loop Strain Rate

Estimated Strain Rate

Method BStress Rate

Stress Rate

5900 Series – Advanced controller, high precision

3300 Series – Affordable accuracy

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Instron Solutions

• Controlling the strain rate during the test gives you more repeatable and comparable results

• Instron's stable, yet responsive, automatic strain control on 5900 controllers removes the need to tune time consuming and complex PID gain terms

• Walk up and test capability over a wide range of metals with various degrees of stiffness (steel, aluminium, etc.)

• No setup required when changing specimen types or strengths

• Compliance with the latest international ISO and ASTM standards

Does this sound familiar?

Do you see the same challenges in your business?

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