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Today, as the current standard tensile test for metallic materials ISO 6892-1 standard are used. The English version of the standard in 2009 and the Turkish version in 2011 were published. The English version was renewed in 2016. In this study, we aimed to summarize the major changes made in this standard. In this way, it is aimed to be transmitted detailed and accurate information for related person.

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3rd Iron and Steel Symposium(UDCS'17)3-5April 2017 Karabuk-TURKEY

The Changes in ISO 6892-1:2016 Metallic Materials

Tensile Testing Standard

Bülent Aydemir*

* TUBITAK UME, Tubitak gebze yerleşkesi, Gebze/Kocaeli/TURKEY, bulent.aydemir@tubitak.gov.tr

Abstract— Today, as the current standard tensile test for metallic

materials ISO 6892-1 standard are used. The English version of

the standard in 2009 and the Turkish version in 2011 were

published. The English version was renewed in 2016. In this study,

we aimed to summarize the major changes made in this standard.

In this way, it is aimed to be transmitted detailed and accurate

information for related person.

Keywords— ISO 6892-1, Tensile test, Metallic materials

I. INTRODUCTION

Along with the developing technology, tensile testing

practice and calculation differences in results bring about

changes in standards. When you search at the changes in the

standard of tensile testing in metallic materials in our country;

TS 138 EN 10002-1(1996, 2004) and TS EN ISO 6892-1(2011)

are published. The English version of the standard is published

in ISO 6892-1(2009), and it is published as TS EN ISO 6892-

1(2011) by the Turkish standard TSE. In 2016, ISO 6892-

1(2016) was revised and published, but Turkish has not been

published yet [1 -3] .

In the metal industry, at room temperature, the tensile test

standard comes out against ISO 6892-1(2016) and ASTM

E8/8M(2016). ASTM standards are used in America, whereas,

ISO standards are used in Europe. Japanese Industrial

Standards (JIS) and GBT (Chinese Standards) in Asia have

adopted the ISO 6892-1 standard.

The tensile test for metallic materials at ISO 6892-1 ambient

temperatures is a very detailed standard. This standard

describes the method to be applied in the experiment, the

calculations used, the results to be reported, as well as the

equipment to be used for the test. The changes in this standard

are likely to affect everyone in the metal industry.

This study has highlighted important changes between the

ISO 6892-1(2016) standard and the previous ISO 6892-1(2009)

standard [1,2]. On this study, it is aimed to give detailed and

accurate information to the persons who are related to the

emphasis of differences of this standard which is used in metal

industry.

II. THE CHANGES OF ISO 6892-1:2016

Its summary is given below those changes between 2016 to

2009 version of ISO 6892-1 tensile testing method of test at

room temperature of metallic materials

A. New terms and definitions

The 2016 version of standard is added the following term

and definitions.

Item 3.12 computer-controlled tensile testing machine:

machine for which the control and monitoring of the test, the

measurements, and the data processing are undertaken by

computer.

Item 3.13 modulus of elasticity (E): quotient of change of

stress ΔR and change of percentage extension Δe in the range

of evaluation, multiplied by 100 %.

Item 3.14 default value: lower or upper value for stress

respectively strain which is used for the description of the range

where the modulus of elasticity is calculated

Item 3.15 coefficient of correlation (R2): additional result of

the linear regression which describes the quality of the stress-

strain curve in the evaluation range

Item 3.16 standard deviation of the slope (Sm): additional

result of the linear regression which describes the difference of

the stress values from the best fit line for the given extension

values in the evaluation range

Item 3.17 relative standard deviation of the slope (Sm(rel)):

quotient of the standard deviation of the slope and the slope in

the evaluation range, multiplied by 100 %.

The symbols of item 4 in the standard are added the new term

defined in item 3 [1,3].

B. The changes in test speeds

Test speeds or test rates in heading 10.3 of ISO 6892-1:2016

standard have been changed and the speeds are explained in

more detail as Method A1, A2 and B, respectively. The

extension speed of the method in the 2009 version of the ISO

6892-1 standard was defined as two methods in the 2016

version. It is expressed as Method A1 (Closed loop strain

control) and Method A2 (Open loop strain control).

Closed loop strain control, method A1, is the strain rate

control based on the feedback of the data obtained from the

instrument's extensometer. The application for this method is

given by the tolerances of the required 4 step speed standard.

The standard speed steps are schematically shown in figure 1

[5-7] . The other method, Method A2, open loop strain control,

3rd Iron and Steel Symposium(UDCS'17)3-5April 2017 Karabuk-TURKEY

involves the control of the estimated strain rate over the parallel

length, (e*Lc ) , which is achieved by using the crosshead

separation speed (vc) calculated by multiplying the required

strain rate by the parallel length. For a better understanding of

this, we can give an example as follows. For a sample with a

parallel length of 80 mm, the required crosshead speed (for the

2nd and 4 th range velocities given in figure 1) should be:

Stress rate control is defined in Method B as standard. This

definition doesn't change from the pr evious version. The

tensile stress rate (Ŕ) varies according to the modulus of

elasticity of the material being applied. These values are given

in Table 1 below.

Fig. 1. Recommended speed ranges according to ISO 6892-1:

2016 standard

In the 2016 version of the standard, the recommended speed

values in Figure 1 are detailed. Speed steps 1,2,3,4,5 for method

A1; 5.6 speed steps for method A2; For the method B, 7 speed

stages can be used.

C. Other changes

The 8th heading of the standard was changed to the

"Marking the original gauge length" in the 2009 version, while

the "Original gauge length and extensometer gauge length" was

changed in the 2016 version. In addition to, the headings of

choice of the original gauge length, marking the original gauge

length and choice of the extensometer gauge length have been

added.

Appendix G, as a new part of the standard, is added specifies

the determination of the modulus of elasticity. In the 2016

version, the names of the other suffixes have changed due to

the addition of Annex G chapter, but the sections remained the

same.

Important information is given in Annex G. For example, it

is stated that the material testing machine has class 1 or better

class according to ISO 7500-1 standard. The extensometer

system is required to have class 0.5 or better class according to

ISO 9513 standard. It is defined that the sample sizes are

measured with a calibrated device with better accuracy than ±

0.5 %. It has also been disclosed that it is important that the

material testing machine is made according to ASTM E1012 or

ISO 23788 in the measurement of the alignment.

In addition, when determining the minimum data sampling

frequency (f), the following formula is proposed:

Where N is the number of measured values, E is the elastic

modulus, ė is the test speed, and R1 , and R2 are the tensile values

that the data sampling frequency is determined. For example, if

R1 = 10 MPa, R2 = 50 MPa for steel, and the test speed is

0.00007 s-1 , the data sampling frequency shall be greater than

18 Hz.

Furthermore, methods of calculating elastic modulus and

calculation of elastic modulus uncertainty are described in

detail.

Apart from these, the bibliography has increased 41 to 58 by

the additional resources given in the Annex G section [1, 3].

III. THE EFFECTS OF TENSILE TEST SPEEDS ( RATES) C HANGES

Testing laboratories should plan to use either Method A1 or

Method A2 according to ISO 6892-1. The method A1 and

Method A2 provide better test applications and more

comparable results. For this reason, it is important to provide

Method A1 when purchasing a new tester or improving your

existing machine, and increasing the efficiency of controlling

the tester, based on the extensometer feedback (Fig. 2).

Alternatively, if your current testing machine can not apply

Method A1, using it at a fixed crosshead speed according to

Method A2 will provide minimal change in results and increase

comparability [5 -7] .

3rd Iron and Steel Symposium(UDCS'17)3-5April 2017 Karabuk-TURKEY

Fig. 2. Graphic representation of extensometer feedback loop

of method A1

The advantage of the methods A1 and A2 is to reduce the

uncertainty of the measurement results of the test results by

reducing the test speeds by minimizing the moment when the

parameters sensitive to strain rate are determined. Figure 3

graphically shows the test speeds according to methods A1 and

A2 and the test parameters that these speeds affect [5].

Fig. 3. ISO6892-1: 2016 Graphic representation of the required

test results with the speeds of method A1 and A2

Fig. 4. Stress-strain graphic of Method A1 and its speeds

chancing

Fig. 5. Stress-strain graphic of Method A2 and its speeds

chancing

The test chart of the method according to ISO 6892-1 and

the closed loop strain control (method A1) is given in figure 4.

In here, the horizontal axis strain (%) shows the vertical axis

stress (MPa) value. The strain rate (mm / mm / min) graph is

shown by the dashed line between ± 20 % tape lines. The

crosshead speed is marked with a large arrow in the graph. The

test chart for the same sample according to ISO 6892-1 method

A2 and the estimated strain (crosshead speed) control is given

in figure 5. In here, it is seen that the strain rate (mm / mm /

min) graph is inserted between ± 20 % band lines after more

strain than figure 4.

Method B stretch rate control has the advantage that it is a

simpler control method and can be used in most test machines.

However, the disadvantages of the test period extension (fig. 6)

are that additional calculations are required for the rigidity of

the machine and that different results can be obtained from the

machine if the machine is not set. During method B testing,

there are many sources of uncertainty and error. Most metallic

materials are sensitive to stress ratio; so, the mechanical

properties vary depending on the test speed.

Stiffness varies according to each machine, and is an

effective parameter on the test results. Figure 6 gives the stress-

percent strain graph for two machines with different stiffness.

For two test rigs, one rigid and the other less rigid, the results

are the same on the average at the same test speed when testing

the same material. To further exaggerate this situation, if the

very rigid system is much faster and the less rigid system is

tested slower, a difference of more than 10 % can be obtained

between the results obtained from the same material [3,5-9].

3rd Iron and Steel Symposium(UDCS'17)3-5April 2017 Karabuk-TURKEY

Fig. 6. Test Machine Rigidity Comparison - two tests were

performed with the same material and at the same crosshead

speed but with two different machines

In the figure given in Figure 7, the test time is given for the

aluminium sample according to different test speeds. As can be

seen, the test carried out in method A1 according to ISO 6892-

1 in the closed loop strain control provides a time saving of

35 % compared to the method A2 and method B control [3, 5-

7].

Fig. 7. Comparison of test times for aluminium samples at

different speeds

IV. CONCLUSIONS

In this study, significant changes were summarized between

the ISO 6892-1 (2016) standard and the previous ISO 6892-1

(2009) standard. In this respect, it is aimed to help the

understanding of this standard which is used in many testing

laboratory in this sector. In addition, the results of the most

important of these changes on the tensile test speed selection

are summarized.

For the purpose of using methods A1 and A2 in ISO 6892-1,

the explanation is as follows: "It is intended to reduce the

measurement uncertainty associated with the change in the test

speed and the test results at which the speed-sensitive

parameters A1 and A2 are to be determined." In addition, - it is

desirable to document the shape of the curve in the test speed

and to document the speed of the test. In addition, the similarity

of test speeds in the reproducibility and reproducibility of the

yield strength results is also important.

A summary table of the test speed methods defined in ISO

6892-1 is given in Table 2 [5]. Inhere the control types and the

feedback sources for the control are given for different

methods. Time-to-install time was measured as the test time,

and the reproducibility values of the test results were given as

comparability. Different test speeds are the most important

affect test time. The aim is that Method A1 provides this for

accurate and reproducible results in the shortest test run.

Table 2. Summary table of test speed methods defined in ISO

6892-1 standard

REFERENCES

[1] ISO 6892-1, (2016), Metallic materials -- Tensile testing -- Part 1:

Method of test at room temperature

[2] ISO 6892-1, (2009), Metallic materials -- Tensile testing -- Part 1:

Method of test at room temperature

[3] B. Aydemir, ISO 6892-1:2016 Metalik Malzemelerin Çekme Deneyi

Standardındaki Değişiklikler ve Etkileri, 2017, Metal Dünyası,

Sayı:283, S.68-72

[4] B. Aydemir, Metalik Malzemelerin Çekme Deney Standardı EN ISO

6892-1'in Getirdiği Değişiklikler, 2013, Makine Teknolojileri

Elektronik Dergisi Cilt: 10, No: 3, 2013 (61-70)

[5] http://www.instron.com.tr/tr-tr/testing-solutions/by-

material/metals/tension/iso-6892-12016

[6] Understanding the New ISO 6892-1:2016 and the Most Notable

Changes: An Interview with Matthew Spiret,

http://www.azom.com/article.aspx?ArticleID=13017

[7] Updates to metals standards 2015, www.instron.com

[8] B. Aydemir, H. Taşcan, C. Camyurdu, Çekme deneyinde farklı uzama

ölçme yöntemlerinin etkilerinin incelenmesi, 2015, Metal Dünyası, Sayı

266, S.44-50, İstanbul

[9] B. Aydemir, Malzeme Deneylerinde (Çekme deneyi) Ölçüm

Belirsizliğinin Hesaplanması Eğitim Dokümanı - G2KV-110, 2015,

G2KV-110, Nisan 2015, TÜBİTAK UME

ResearchGate has not been able to resolve any citations for this publication.

Bulent Aydemir

Metalik malzemelerde çekme deney standardı olarak TS 138 EN 10002-1 standardı kullanılmakta idi. Yeni yayınlanan TS EN ISO 6892-1 standardı eski standardın yerini almış ve ilave gereklilikleri de kapsayacak şekilde düzenlenmiştir. Ülkemizde metalik malzemelerin çekme deneyi uygulamalarında kullanılmakta olan standardın farklılıkları çalışmada özetlenmesi amaçlanmıştır. Bu sayede, konu ile ilgili kişilere detaylı ve doğru bir bilgi iletilmesi hedeflenmiştir. Sonuç olarak yeni standardın gerekliliklerini karşılamak amacıyla cihazlarda ve deney prosedürlerinde değişiklikleri neler olması gerektiği verilmiştir.

Bulent Aydemir

Günümüzde metalik malzemeler için çekme deneyi güncel standardı olarak ISO 6892-1 standardı kullanılmaktadır. Standardın 2009 yılında ingilizce versiyonu ve 2011 yılında Türkçe versiyonu yayınlandı. 2016 yılında İngilizce versiyonu yenilendi. Bu çalışmada, standartta yapılan önemli değişikliklerin özetlenmesi amaçlanmıştır. Bu sayede, konu ile ilgili kişilere detaylı ve doğru bir bilgi iletilmesi hedeflenmiştir.

Malzeme Deneylerinde (Çekme deneyi) Ölçüm Belirsizliğinin Hesaplanması Eğitim Dokümanı-G2KV-110