GB/T 17600.1-1998Steel. Conversion of elongation values. Part 1: Carbon and low alloy steels (English PDF)

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.

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 25sqrt S 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 […]

4 Symbols

lambda Conversion factor for elongations on different proportional gauge lengths

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

beta Conversion factor between 5.65sqrt S gauge length and elongation of different non-proportional gauge lengths

gamma Conversion factor between elongation of 4sqrt S gauge length and elongation of different non-proportional gauge lengths

5 Elongation conversions

5.2 Conversion from the elongation of one proportional gauge length to the elongation of another proportional gauge length

Calculate the (K/K tau)0.4 value of the commonly used proportional test piece according to formula (2). The conversion factor is denoted as lambda, which is listed in Table 2. Then deltatau = lambda . delta.

Example: It is known that the elongation of 5.65sqrt S gauge length is 25 %, which is to be converted to the elongation of 11.3sqrt S gauge length. Look up Table 2, lambda = 0.758, then deltatau = 0.758 x 25 % = 18.95 %, which is rounded off to 19 %.

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 5.65sqrt S gauge length is known, and it is to be converted to the elongation of other non-proportional gauge lengths, then.

Calculate the 2(sqrt S/L0 tau)0.4 value. The conversion factor is denoted as beta, which is listed in Table 4. Then deltatau = beta . delta.

If the elongation of 4sqrt S gauge length is known, and it is to be converted to the elongation of other non-proportional gauge lengths, then.

Calculate the 1.74(sqrt S/L0 tau)0.4 value. The conversion factor is denoted as gamma, which is listed in Table 5. Then deltatau = gamma . delta.

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

Table 3 -- Conversion factor alpha 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 5.65sqrt S or 4sqrt S; then convert it to the elongation of the non-proportional gauge length to be obtained.

Example: The elongation of 40 mm x 15 mm test piece with 200 mm gauge length is 24 %, which is to be converted to 30 mm x 10 mm test piece with 200 mm, 100 mm and 50 mm gauge lengths.

Firstly, according to Table 4, convert to the elongation of 5.65sqrt S gauge length, that is 24 % x 1/0.863 = 27.81 %;

convert to the elongation of 30 mm x 10 mm, 200 mm gauge length, i.e. deltatau = 27.81 % x 0.752 = 20.91 % (see Table 4), which is rounded off to 21%;

convert to the elongation of 30 mm x 10 mm, 100 mm gauge length, deltatau = 27.81 % x 0.992 = 27.58 %, which is rounded off to 28 %;

convert to the elongation of 30 mm x 10 mm, 50 mm gauge length, deltatau = 27.81 % x 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 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 5.65sqrt S and 50 mm gauge lengths. Figure 2 is for elongation conversions between 5.65sqrt S and 200 mm gauge lengths.

Example: For 25 mm x 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 5.65sqrt S 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 5.65sqrt S 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 4sqrt S and 50 mm and between 4sqrt S 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 lambda = (K/K tau)0.4 of formula (2), i.e..

It is used to obtain the conversion factor lambda of various types of test pieces. It shall operate as follows.

a) calculate the proportionality coefficients K = L0/sqrt S and K tau = L0 tau/sqrt S for two test pieces;

b) read the conversion factor lambda from Figure 5, that is, find K on the abscissa, find K tau on the ordinate, and the value corresponding to the oblique line passing through the intersection point is the lambda value;

c) the elongation obtained is deltatau = lambda . delta.

Example: For 14 mm x 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- […]