Standards related to:

GB/T 17600.1-1998**GB/T 17600.1-1998: PDF in English (GBT 17600.1-1998) **

GB/T 17600.1-1998

GB

NATIONAL STANDARD OF THE

PEOPLE’S REPUBLIC OF CHINA

ICS 77.040.10

H 22

eqv ISO 2566-1.1984

Steel - Conversion of elongation values -

Part 1. Carbon and low alloy steels

ISSUED ON. DECEMBER 07, 1998

IMPLEMENTED ON. JULY 01, 1999

Issued by. China Quality and Technology Supervision Bureau

Table of Contents

Foreword ... 3

ISO foreword ... 5

1 Scope ... 6

2 References ... 6

3 Definitions ... 7

4 Symbols ... 7

5 Elongation conversions ... 8

6 Use of graphs... 11

Foreword

This Standard is equivalent to the International Standard ISO 2566-1.1984

“Steel - Conversion of elongation values - Part 1. Carbon and low alloy steels”.

This Standard is identical to ISO 2566-1.1984 in terms of scope of application

and conversion formula for elongation conversions. Therefore, the conversion

results are completely consistent and technically equivalent.

This Standard has the following differences from the ISO standard.

1. This Standard gives the basic formula of conversion and the specific

conversion formula under various conditions. The ISO standard only gives

the specific conversion formula under two conditions.

2. The conversion formula given in this Standard contains the calculation

formulas in all the conversion tables in the ISO standard. Therefore, the

21 conversion tables in the ISO standard are reduced to 4.

3. The symbols used in this Standard are consistent with GB/T 228-1987

“Metallic materials - Tensile testing” and GB/T 10623-1989 “Metallic

materials - Terms of mechanical test”, which are slightly different from the

ISO standard.

4. The mantissa of the individual values in the conversion factor table of this

Standard is slightly different from the ISO standard. They are rounded off

in this Standard according to GB/T 8170-1987 “Rules for rounding off of

numerical values”.

GB/T 17600 consists of two parts under the general title of “Steel - Conversion

of elongation values”.

GB/T 17600. 1-1998 Part 1. Carbon and low alloy steels

GB/T 17600. 2-1998 Part 2. Austenitic steels

YB 4080-1992 “Steel - Conversion of elongation values (Carbon and low alloy

steels)” is invalidated from the date of implementation of this Standard.

This Standard was proposed by the former Ministry of Metallurgical Industry of

the People's Republic of China.

This Standard shall be under the jurisdiction of National Technical Committee

on Steel of Standardization Administration of China.

Drafting organizations of this Standard. Kunming Iron and Steel Corporation,

Steel - Conversion of elongation values -

Part 1. Carbon and low alloy steels

1 Scope

This Standard specifies a method of converting room temperature elongations

after fracture obtained on various gauge lengths. It includes the conversion

formula and the conversion factor table of the elongation, as well as the graphs

for performing such conversions.

This Standard is applicable to carbon and low alloy steels within the tensile

strength range 300 to 700 MPa and in the hot-rolled, hot-rolled and normalized

or annealed conditions, with or without tempering.

This Standard is not applicable to cold rolled (drawn) steels, quenched and

tempered steels and austenitic steels.

This Standard is not applicable to the test piece of which the original gauge

length exceeds 25ඥ𝑆 or the test piece of which the width to thickness ratio

exceeds 20.

In the case of strip test piece under 4 mm thickness, the index n in formula (1)

of this Standard increases with decreasing thickness. The conversion value of

elongation shall be the subject of agreement between the customer and the

supplier.

The conversion method of this Standard is adopted internationally, and the

conversions are reliable within the scope of this Standard. However, because

of the various factors influencing the determination of elongations, whether to

use the conversions of this Standard shall be determined by the relevant

standards or agreements

In cases of dispute or arbitration, the elongation value shall be determined on

the gauge length stated in the relevant standards or agreements.

2 References

The following standards contain provisions which, through reference in this

Standard, constitute provisions of this Standard. At the time of publication, the

editions indicated are valid. All standards are subject to revision. The parties

λ Conversion factor for elongations on different proportional gauge lengths

α Conversion factor for elongations on different non-proportional gauge lengths

β Conversion factor between 5.65ඥ𝑆 gauge length and elongation of different non-proportional gauge lengths

γ Conversion factor between elongation of 4ඥ𝑆 gauge length and elongation of different non-proportional gauge lengths

5 Elongation conversions

5.1 Basic formula

The conversion of elongation is based on the Oliver formula. The basic formula

used for conversions may expressed as.

or

For ease of use, this Standard gives the simplified formula and conversion

factor derived from the basic formula, used under different conditions, and

draws graphs according to the formula, from which the conversion value of the

elongation may be directly found.

NOTE. The conversion value of the elongation in this Standard is rounded off according to the

corresponding clause of GB/T 228 and GB/T 8170.

5.2 Conversion from the elongation of one proportional gauge length to

the elongation of another proportional gauge length

Calculate the (K/Kτ)0.4 value of the commonly used proportional test piece

according to formula (2). The conversion factor is denoted as λ, which is listed

in Table 2. Then δτ = λ • δ.

Example. It is known that the elongation of 5.65ඥ𝑆 gauge length is 25 %,

which is to be converted to the elongation of 11.3ඥ𝑆 gauge length. Look up

Table 2, λ = 0.758, then δτ = 0.758 × 25 % = 18.95 %, which is rounded off to

19 %.

5.3 Conversion from the elongation of one non-proportional gauge length

to the elongation of another non-proportional gauge length for test pieces

of equal cross-sectional area

The basic formula is simplified to.

Calculate the (L0/L0τ)0.4 value of the commonly used non-proportional test piece.

The conversion factor is denoted as α, which is listed in Table 3. Then δτ = α •

δ.

Example. It is known that the measured elongation of the test piece with a 200

mm non-proportional gauge length is 20 %, which is to be converted to the

elongation of 100 mm gauge length with the same cross-sectional area. Look

up Table 3, it is known that α = 1.320, then δτ = 1.320 × 20 % = 26.40 %, which

is rounded off to 26 %.

5.4 Conversion from the elongation of a proportional gauge length to the

elongation of a non-proportional gauge length

The basic formula is simplified to.

If the elongation of 5.65ඥ𝑆 gauge length is known, and it is to be converted to

the elongation of other non-proportional gauge lengths, then.

Calculate the 2(ඥ𝑆ఛ/L0τ)0.4 value. The conversion factor is denoted as β, which

is listed in Table 4. Then δτ = β • δ.

If the elongation of 4ඥ𝑆 gauge length is known, and it is to be converted to the

elongation of other non-proportional gauge lengths, then.

Calculate the 1.74(ඥ𝑆ఛ/L0τ)0.4 value. The conversion factor is denoted as γ,

which is listed in Table 5. Then δτ = γ • δ.

Other proportional gauge lengths may also be converted to the elongation of

Table 3 -- Conversion factor α for elongations of different non-

proportional gauge lengths (with the same cross-sectional area)

Key.

A - Original gauge length of the test piece of which the elongation is to be measured, L0.

5.5 Conversion from the elongation of a non-proportional gauge length to

the elongation of another non-proportional gauge length for test pieces

of different cross-sectional areas

Convert according to formula (1). It may also convert in two steps using Table

4 or Table 5. Firstly, convert the elongation of the known gauge length to the

elongation of the proportional gauge length, such as 5.65ඥ𝑆ఛ or 4ඥ𝑆ఛ; then

convert it to the elongation of the non-proportional gauge length to be obtained.

Example. The elongation of 40 mm × 15 mm test piece with 200 mm gauge

length is 24 %, which is to be converted to 30 mm × 10 mm test piece with 200

mm, 100 mm and 50 mm gauge lengths.

Firstly, according to Table 4, convert to the elongation of 5.65ඥ𝑆 gauge length,

that is 24 % × 1/0.863 = 27.81 %;

convert to the elongation of 30 mm × 10 mm, 200 mm gauge length, i.e. δτ =

27.81 % × 0.752 = 20.91 % (see Table 4), which is rounded off to 21%;

convert to the elongation of 30 mm × 10 mm, 100 mm gauge length, δτ = 27.81 %

× 0.992 = 27.58 %, which is rounded off to 28 %;

convert to the elongation of 30 mm × 10 mm, 50 mm gauge length, δτ = 27.81 %

× 1.309 = 36.40 %, which is rounded off to 36 %.

The elongation of other proportional gauge lengths may be converted according

to the conversion factors given in Table 2.

6 Use of graphs

6.1 Figures 1 to 5 may be used as an alternative quick method for elongation

Conversion factor α for conversions to the following non-proportional gauge lengthsA

conversions.

6.2 Figures 1 and 2 are obtained by taking the logarithm on both sides of the

equation according to formula (5). Figure 1 is used for elongation conversions

between 5.65ඥ𝑆 and 50 mm gauge lengths. Figure 2 is for elongation

conversions between 5.65ඥ𝑆 and 200 mm gauge lengths.

Example. For 25 mm × 12.5 mm test piece with a cross-sectional area of 312.5

mm2 and a gauge length of 200 mm, the elongation is 21 %. It is to obtain the

elongation of 5.65ඥ𝑆 gauge length.

Find 312.5 mm2 on the abscissa and find 21 on the ordinate of Figure 2. The

value corresponding to the oblique line passing through the intersection point

is 27.7 %, which is rounded off to 28 %, that is the elongation of 5.65ඥ𝑆 gauge

length to be obtained.

6.3 Figures 3 and 4 are obtained by taking the logarithm on both sides of the

equation according to formula (6). They are used for elongation conversions

between 4ඥ𝑆 and 50 mm and between 4ඥ𝑆 and 200 mm, respectively, using

the same method as 6.2.

6.4 Figure 5 is obtained by taking the logarithm of the conversion factor λ = (K/

Kτ)0.4 of formula (2), i.e..

It is used to obtain the conversion factor λ of various types of test pieces. It shall

operate as follows.

a) calculate the proportionality coefficients K = L0/ඥ𝑆 and Kτ = L0τ/ඥ𝑆ఛ for

two test pieces;

b) read the conversion factor λ from Figure 5, that is, find K on the abscissa,

find Kτ on the ordinate, and the value corresponding to the oblique line

passing through the intersection point is the λ value;

c) the elongation obtained is δτ = λ • δ.

Example. For 14 mm × 30 mm plate test piece with a cross-sectional area of

420 mm2 and a L0 = 200 mm gauge length, the measured elongation is 20 %.

It is to be converted to the elongation at L0 = 100 mm under the same cross-

......

Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.