Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 21839-2008 Steel for prestressed concrete - Test methods. In addition to a number of editorial changes, the following technical changes have been made with respect to GB/T 21839-2008:
——The normative references are modified (see Clause 2; Clause 2 of Edition 2008);
——Some symbols are modified and added (see Clause 3; Clause 3 of Edition 2008);
——The general provisions concerning test pieces are modified (see Clause 4; Clause 4 of Edition 2008);
——Tensile test is modified; requirements for tensile test pieces are added, parameters A and Z are added for the measurement in tensile test, artificial method is added for the measurement of Agt according to GB/T 228.1; measurement of modulus of elasticity (E) is refined (see 5.3.2);
——Judgment of the bend test result is modified (see 6.4; 6.4 of Edition 2008);
——Equipment for reverse bend test is added (see 7.2);
——Adhesion test of coating is added (see Clause 9);
——Relevant technical requirements of extensometer are modified (see Clause 5 and Annex C; Clause 5 and Annex A of Edition 2008);
——Safety warning for chemical reagents is added at the part of stress corrosion test solution (see 12.3.5);
——Requirements for length of indentation are added (see 15.3.2.4);
——Testing of the content of anti-corrosive grease is added (see Clause 18);
——Measurement of sheath thickness is added (see Clause 19);
——Test for uniformity of coating is added (see Clause 20);
——Test for quality of zinc coating is added (see Clause 21).
This standard has been redrafted and modified in relation to ISO 15630-3:2010 Steel for the reinforcement and prestressing of concrete - Test methods - Part 3: Prestressing steel.
Many structural adjustments have been made with respect to ISO 15630-3:2010, and a comparison table between this standard and ISO 15630-3:2010 in clause/subclause number is listed in Annex A.
This standard includes technical differences with respect to ISO 15630-3:2010. The clauses and subclauses concerned are identified by a vertical single line (|) located in the blank on its external margin of the page. These technical differences and their causes are listed in Annex B.
In addition, the following editorial changes have been made in this standard:
——“Annex A (informative) Comparison between this standard and ISO 15630-3:2010 in clause/subclause number” is added;
——“Annex B (Informative) Technical differences and their causes between this standard and ISO 15630-3: 2010” is added.
——“Annex C (Informative) Methods for tensile test of strand for prestressing concrete” is added.
This standard was proposed by China Iron and Steel Industry Association.
This standard is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
The previous edition of this standard is as follows:
—GB/T 21839-2008.
Test methods of steel for prestressing concrete
1 Scope
This standard specifies the methods concerning tensile test, bend test, reverse bend test, torsion test, adhesion test of winding and coating, isothermal relaxation test, axial force fatigue test, stress corrosion test in a solution of thiocyanate, deflected tensile test, determination of chemical composition, measurement of the geometrical dimension, determination of the relative rib area, determination of deviation from nominal weight per metre, testing of the content of anti-corrosive grease, measurement of sheath thickness, test for uniformity of coating and test for quality of galvanized coating, etc. of steel for prestressing concrete.
This standard is applicable to the determination of properties related prestressing steel wire, prestressing steel rod, prestressing steel bar, prestressing steel strand and other products.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature (GB/T 228.1-2010, ISO 6892-1:2009, MOD)
GB/T 230.1 Metallic materials - Rockwell hardness test - Part 1: Test method (GB/T 230.1-2018, ISO 6508-1:2016, MOD)
GB/T 232 Metallic materials - Bend test (GB/T 232-2010, ISO 7438:2005, MOD)
GB/T 238 Metallic materials - Wire - Reverse bend test (GB/T 238-2013, ISO 7801:1984, MOD)
GB/T 239.1 Metallic materials - Wire - Part 1: Simple torsion test (GB/T 239.1-2012, ISO 7800:2003, MOD)
GB/T 1839 Test method for gravimetric determination of the mass per unit area of galvanized coatings on steel products (GB/T 1839-2008, ISO 1460:1992, MOD)
GB/T 2972 Test method for uniformity of zinc coating on zinc-coated steel wire by the copper sulphate dip (GB/T 2972-2016, ISO 7989-2:2007, NEQ)
GB/T 2975 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing (GB/T 2975-2018, ISO 377:2017, MOD)
GB/T 2976 Metallic materials - Wire - Wrapping test (GB/T 2976-2004, ISO 7802:1983, IDT)
GB/T 3505 Geometrical product specifications (GPS) - Surface texture: Profile method - Terms definitions and surface texture parameters (GB/T 3505-2009, ISO 4287:1997, IDT)
GB/T 4336 Carbon and low-alloy steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (routine method)
GB/T 12160 Calibration of extensometers used in uniaxial testing (GB/T 12160-2002, ISO 9513:1999, IDT)
GB/T 16825.1 Verification of static uniaxial testing machines - Part 1: Tension/compression testing machines - Verification and calibration of the force-measuring system (GB/T 16825.1-2008, ISO 7500-1:2004, IDT)
3 Symbols and definitions
For the purposes of this document, the symbols given in Table 1 apply.
Table 1 Symbols and their description
Symbol Unit Description Reference
am mm Rib height at the mid-point 15.3, 16.2
amax mm Maximum depth of indentation or height of rib 15.3
as,i mm Average height of a rib in unit length ∆l 16.2
a1/4 mm Rib height at the quarter-point 15.3, 16.2
a3/4 mm Rib height at the three-quarters point 15.3, 16.2
A % Percentage elongation after fracture 5.3.1
Agt % Percentage total elongation at maximum force 5
At % Total elongation at break 5.3.1
b mm Width of transversal rib 15.3.1.6
c mm Rib or indentation spacing 15.3
C mm Groove width of the mandrel used for the deflected tensile test 13.3.4
d mm Nominal diameter of the rod, wire or strand 11.2, 11.4.6, 12.3.4
da mm Nominal diameter of the mandrel used for the deflected tensile test 13.3.4
db mm Diameter with 2 gauge cylinders in the groove of the mandrel used for the deflected tensile test 13.3.4
de mm Diameter of the gauge cylinder used for the deflected tensile test 13.3.4
dg mm Diameter of guide hole 7.3
di mm Inner diameter of the groove of the mandrel used for the deflected tensile test 13.3.4
D % Average coefficient of reduction of the maximum force in the deflected tensile test 13.2, 13.4
Dc mm Inner diameter of the cell in the stress corrosion test 12.3.4
Di % Individual percentage of reduction of the maximum force in the deflected tensile test 13.4
e mm Average gap between two adjacent ribs or indentation rows 15.3.1.4, 15.3.2.4
E GPa Modulus of elasticity 5.3
f HZ Frequency of force cycles in the axial force fatigue test 11.1, 11.4.2
fR — Relative rib area 16
Fa,i N Individual breaking force in the deflected tensile test 13.4
Fm N Maximum force 5.3
N Mean value of the maximum force 10.2, 12.2, 13.2
Fp0.1 N 0.1% proof force 5.3
Fp0.2 N 0.2% proof force 5.3
Fr N Force range in the axial force fatigue test 11.1, 11.3, 11.4.2
Frt N Residual force in the test piece at time t in the relaxation test 10.1
ΔFrt N Force loss in the test piece at time t in the relaxation test 10.1
FR mm2 Area of longitudinal section of one transverse rib 16.2
Fup N Upper force in the axial force fatigue test 11.1, 11.3, 11.4.2
F0 N Initial force in the stress relaxation test and the stress corrosion test 10.1, 10.3, 10.4, 12.4.2
G mm Depth of the groove of the mandrel used for the deflected tensile test 13.3.4
h mm Distance from the top of cylindrical supports to the bottom of the guide 7.2
hb mm Bow height of the plane of prestressing steel 15.3.4
Lt mm Length of the test piece in the stress corrosion test 12.2
L0 mm Original gauge length in the isothermal relaxation test
Length of the test piece in contact with the solution in the stress corrosion test 10.1, 10.3, 10.4, 12.2, 12.3.4, 12.4.5
ΔL0 mm Elongation of the gauge length, L0, under force, F0, in the isothermal stress relaxation test 10.1, 10.3, 10.4
L'0 mm Determined original gauge length of Agt 5.3
L'u mm Determined gauge length after fracture of Agt 5.3
L1 mm Length of the passive side in the deflected tensile test 13.3.2
L2 mm Length of the active side in the deflected tensile test 13.3.2
m, n — Coefficients or numbers 10.4.9, 15.3, 16.2
P mm Lay length of a strand 15.3.3
R mm Corner radius at the base of the groove of the mandrel used for the deflected tensile test 13.3.4
r mm Radius of cylindrical supports 7.2
Ra μm Surface roughness of the mandrel used for the deflected tensile test 13.3.4
Sn mm2 Nominal cross-sectional area of the test piece 5.3.2
ta h Maximum agreed time for the stress corrosion test 12.4.5
tf,i h Individual lifetime to fracture in the stress corrosion test 12.4.5
h Median lifetime to fracture in the stress corrosion test 12.4.6
t0 s Starting time in the isothermal stress relaxation test and in the stress corrosion test 10.4.2, 12.4
V0 mm3 Volume of test solution to fill the test cell in the stress corrosion test 12.4.3
W g/m Weight of unbonded prestressing steel strand per metre 18.3
W1 g/m Weight of steel strand after removing the sheath and anti-corrosive grease from unbonded prestressing steel strand per metre 18.3
W2 g/m Weight of sheath after removing the anti-corrosive grease from unbonded prestressing steel strand per metre 18.3
W3 g/m Weight of anti-corrosive grease in unbonded prestressing steel strand per metre 18.3
Z % Percentage reduction of area 5.3.1
α (°) Angle of deviation in the deflected tensile test 13.3.2
β (°) Transverse rib or indentation angle to the bar or wire axis 15.3
εx — Value of the strain for a force equal to x 5.3.2
ρ % Relaxation 10.4.8
Σei mm Circumference of transverse rib gap 15.3.1.4, 15.3.2.4, 16.2
Note: 1N/mm2=1MPa
4 General provisions concerning test pieces
Unless otherwise agreed or specified in the product standard, the test pieces shall be taken from the finished product normally before packaging.
Special care should be taken when sampling is made from the packaged product (e.g. coil or bundle), in order to avoid plastic deformation which could change the properties of the samples used to provide the test pieces.
Specific complementary provisions concerning the test pieces may be indicated in the relevant clauses of this standard, if applicable.
5 Tensile test
5.1 Test pieces
In addition to the general provisions given in Clause 4, the free length of the test piece shall be sufficient for the determination of the percentage total elongation at maximum force (Agt) in accordance with 5.3.1.
If the percentage elongation after fracture is determined manually, the test piece shall be marked in accordance with GB/T 228.1.
If the percentage total elongation at maximum force (Agt) is determined by the manual method for bar or wire, equidistant marks shall be made on the free length of the test piece (see GB/T 228.1). The distance between the marks shall be 20mm, 10mm or 5mm, depending on the test piece diameter.
Foreword i
1 Scope
2 Normative references
3 Symbols and definitions
4 General provisions concerning test pieces
5 Tensile test
6 Bend test
7 Reverse bend test
8 Torsion test
9 Adhesion test of winding and coating
10 Isothermal relaxation test
11 Axial force fatigue test
12 Stress corrosion test in a solution of thiocyanate
13 Deflected tensile test
14 Chemical analysis
15 Measurement of the geometrical dimension
16 Determination of the relative rib area (fR)
17 Determination of deviation from nominal weight per metre
18 Testing of the content of anti-corrosive grease
19 Measurement of sheath thickness
20 Test for uniformity of coating
21 Test for quality of zinc coating
22 Test report
Annex A (Informative) Comparison between this standard and ISO 15630-3: 2010 in clause/subclause number
Annex B (Informative) Technical differences and their causes between this standard and ISO 15630-3:
Annex C (Informative) Methods for tensile test of strand for prestressing concrete
预应力混凝土用钢材试验方法
1 范围
本标准规定了预应力混凝土用钢材的拉伸、弯曲、反复弯曲、扭转、缠绕和镀层附着力、等温松弛、轴向力疲劳、硫氰酸盐溶液中的应力腐蚀、偏斜拉伸、化学分析、几何尺寸测量、相对肋面积确定、每米公称质量偏差的确定、防腐润滑脂含量检测、护套厚度测量、镀层均匀性、锌层质量等试验方法。
本标准适用于预应力钢丝、预应力钢棒、预应力钢筋、预应力钢绞线等产品相关性能的测定。
2 规范性引用文件
下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件，仅注日期的版本适用于本文件。凡是不注日期的引用文件，其最新版本(包括所有的修改单)适用于本文件。
GB/T 228.1 金属材料 拉伸试验 第1部分：室温试验方法(GB/T 228.1—2010，ISO 6892-1：2009，MOD)
GB/T 230.1 金属材料 洛氏硬度试验 第1部分：试验方法(GB/T 230.1—2018，ISO 6508-1：2016，MOD)
GB/T 232 金属材料 弯曲试验方法(GB/T 232—2010，ISO 7438：2005，MOD)
GB/T 238 金属材料 线材 反复弯曲试验方法(GB/T 238—2013，ISO 7801：1984，MOD)
GB/T 239.1 金属材料 线材 第1部分：单向扭转试验方法(GB/T 239.1—2012，ISO 7800：2003，MOD)
GB/T 1839 钢产品镀锌层质量试验方法(GB/T 1839—2008，ISO 1460：1992，MOD)
GB/T 2972 镀锌钢丝锌层硫酸铜试验方法(GB/T 2972—2016，ISO 7989-2：2007，NEQ)
GB/T 2975 钢及钢产品 力学性能试验取样位置和试样制备(GB/T 2975—2018，ISO 377：2017，MOD)
GB/T 2976 金属材料 线材 缠绕试验方法(GB/T 2976—2004，ISO 7802：1983，IDT)
GB/T 3505 产品几何技术规范(GPS) 表面结构 轮廓法 术语、定义及表面结构参数(GB/T 3505—2009，ISO 4287：1997，IDT)
GB/T 4336 碳素钢和中低合金钢 多元素含量的测定 火花放电原子发射光谱法(常规法)
GB/T 12160 单轴试验用引伸计的标定(GB/T 12160—2002，ISO 9513：1999，IDT)
GB/T 16825.1 静力单轴试验机的检验 第1部分：拉力和(或)压力试验机测力系统的检验与校准(GB/T 16825.1—2008，ISO 7500-1：2004，IDT)
3 符号及说明
表1给出的符号及说明适用于本文件。
表1 符号及说明
符号 单位 说明 涉及章条
am mm 中点肋高 15.3,16.2
amax mm 刻痕深度最大值/最高点肋高 15.3
as,i mm 肋在单位长度Δl上的平均高度 16.2
a1/4 mm 在1/4点处的肋高 15.3,16.2
a3/4 mm 在3/4点处的肋高 15.3,16.2
A % 断后伸长率 5.3.1
Agt % 最大力总延伸率 5
At % 断裂总延伸率 5.3.1
b mm 横肋宽 15.3.1.6
c mm 肋或刻痕距 15.3
C mm 偏斜拉伸试验用的芯轴凹槽宽度 13.3.4
d mm 预应力钢棒、钢丝、钢绞线的公称直径 11.2,11.4.6,12.3.4
da mm 偏斜拉伸试验用芯轴公称直径 13.3.4
db mm 偏斜拉伸试验用两量棒放在芯轴凹槽中的直径 13.3.4
de mm 偏斜拉伸试验用量棒的直径 13.3.4
dg mm 导向孔直径 7.3
di mm 偏斜拉伸试验用芯轴凹槽的内径 13.3.4
D % 偏斜拉伸试验中最大力减少率的平均值 13.2,13.4
Dc mm 应力腐蚀试验中容器内径 12.3.4
Di % 偏斜拉伸试验中单根试样最大力减少的百分比 13.4
e mm 两排相邻的肋或刻痕之间的平均间隙 15.3.1.4,15.3.2.4
E GPa 弹性模量 5.3
f HZ 轴向疲劳试验中负荷循环频率 11.1,11.4.2
fR — 相对肋面积 16
Fa,i N 偏斜拉伸试验中单根试样破断力 13.4
Fm N 最大力 5.3
N 最大力平均值 10.2,12.2,13.2
Fp0.1 N 0.1%屈服力 5.3
Fp0.2 N 0.2%屈服力 5.3
Fr N 轴向疲劳试验中力的范围 11.1,11.3,11.4.2
Frt N 松弛试验t时间试样上的剩余力 10.1
ΔFrt N 松弛试验t时间试样松弛损失的力 10.1
FR mm2 横肋轴向剖面面积 16.2
Fup N 轴向疲劳试验中的最大力 11.1,11.3,11.4.2
F0 N 应力松弛试验和应力腐蚀试验中的初始力 10.1,10.3,10.4,12.4.2
G mm 偏斜拉伸试验用芯轴凹槽深度 13.3.4
h mm 圆柱支座顶部至拨杆底部距离 7.2
hb mm 预应力钢材平面矢高 15.3.4
Lt mm 应力腐蚀试验中试样的长度 12.2
L0 mm 等温松弛试验原始标距，应力腐蚀试验中试样在溶液中的浸入长度 10.1,10.3,10.4
12.2,12.3.4,12.4.5
ΔL0 mm 等温应力松弛试验中在力F0时标距L0的伸长 10.1,10.3,10.4
L'0 mm 测定Agt的原始标距 5.3
L'u mm 测定Agt的断后标距 5.3
L1 mm 偏斜拉伸试验中固定端长度 13.3.2
L2 mm 偏斜拉伸试验中活动端长度 13.3.2
m,n — 系数或数字 10.4.9,15.3,16.2
P mm 钢绞线捻距 15.3.3
R mm 偏斜拉伸试验中芯轴凹槽底部圆角半径 13.3.4
r mm 圆柱支撑半径 7.2
Ra μm 偏斜拉伸试验中芯轴表面粗糙度 13.3.4
Sn mm2 试样公称横截面积 5.3.2
ta h 应力腐蚀试验中最大规定时间 12.4.5
tf,i h 应力腐蚀试验中单根试样的断裂时间 12.4.5
tf h 应力腐蚀试验中试样断裂时间中值 12.4.6
t0 s 恒温松弛试验和应力腐蚀试验中开始时间 10.4.2,12.4
V0 mm3 应力腐蚀试验容器中溶液的体积 12.4.3
W g/m 每米长无粘结预应力钢绞线的质量 18.3
W1 g/m 每米长无粘结预应力钢绞线中除净护套和防腐润滑脂后的钢绞线的质量 18.3
W2 g/m 每米长无粘结预应力钢绞线中除净防腐润滑脂后的护套的质量 18.3
W3 g/m 每米长无粘结预应力钢绞线中防腐润滑脂的质量 18.3
Z % 断面收缩率 5.3.1
α (°) 偏斜拉伸试验中偏斜角度 13.3.2
β (°) 钢棒或钢丝的横肋或刻痕与中心线的夹角 15.3
εx — X应变支 5.3.2
ρ % 松弛率 10.4.8
Σei mm 横肋间隙周长 15.3.1.4,15.3.2.4,16.2
注：1N/mm2=1MPa。
4 试样的一般规定
除非另有其他协议或产品标准规定，试样一般在成品包装前在成品中截取。
当样品是包装产品时(例如成卷或成捆)，截取试样应防止试样因发生塑性变形而可能改变其性能。
必要时，可对本标准相关条款中试样的要求进行具体补充。
5 拉伸试验
5.1 试样
试样应符合第4章的规定，测定最大力总延伸率(Agt)时，试样的自由长度应符合5.3.1的Agt相关要求。
手工法测定断后伸长率时，按照GB/T 228.1要求划等距离标记。
用手工法测定钢丝和钢棒最大力总延伸率(Agt)时，在试样自由长度上划等距离标记(见GB/T 228.1)，标记间的距离根据样品的直径确定，可为20mm、10mm 或5mm。
5.2 试验设备
试验设备应根据GB/T 16825.1进行校验和校准，并至少为1级准确度。
测定E、Fp0.1或Fp0.2时，引伸计的准确度应为1级(见GB/T 12160)；用于测定Agt的引伸计可以为2级(见GB/T 12160)。
应使用合适的夹具，避免试样在夹具内或在夹具附近断裂。
5.3 试验程序
5.3.1 概述
5.3.1.1 拉伸试验应按照GB/T 228.1的要求执行；预应力混凝土用多丝钢绞线拉伸试验程序可参照附录C执行。
5.3.1.2 应该使用引伸计测定弹性模量(E)，0.1%屈服力和0.2%屈服力(Fp0.1和Fp0.2)及最大力总延伸率(Agt)，引伸计的标距按相关产品的标准要求确定。
5.3.1.3 Agt的精确值只能用引伸计来测得。如果试样上的引伸计不能保持到试样断裂时，可按下列方法测定Agt：
——继续加载直至引伸计记录的伸长率稍大于Fp0.2时的伸长率，此时取下引伸计，记录试验机上下工作台的距离。继续加载至试样断裂，记录此时试验机上下工作台的最终距离。
——计算出两次试验机上下工作台的距离之差，将此差值与试验机上下工作台的初始距离之比和用引伸计测得的百分数相加即为断裂总延伸率At。
5.3.1.4 对于钢丝、钢棒、钢筋Agt测定，应按照下列方法进行：
测量已拉伸试验过的试样最长部分，测量区的范围应处于距离断裂处至少5d，距离夹头至少为2.5d。测量用的原始标距应等于产品标准中规定的值。
按下列式(1)计算：
(1)
式中：
L'u——测定Agt的断后标距；
L'0——测定Agt的原始标距。
5.3.1.5 在装引伸计前，宜给试样预加一负荷，例如该预加负荷为试样预期最大负荷的约10%。
5.3.1.6 如果Agt不是完全用引伸计测定的，应在试验报告中注明。
5.3.1.7 拉伸性能值，Fp0.1，Fp0.2，Fm均用力的单位表示。
5.3.1.8 断后伸长率(A)测定原始标距为试样公称直径的8倍，除非相关产品标准另有规定。在有争议的情况下，A 的测定采用手工法。
5.3.1.9 当试样在距夹具3mm 之内发生断裂，试验应判为无效，应允许重新试验。然而，如果所有试验数据大于等于相应的规定值，其试验结果有效。
5.3.2 弹性模量的测定
在力-伸长率曲线中，用0.2Fm~0.7Fm范围内的直线段的斜率除以试样的公称横截面积(Sn)测定弹性模量(E)。
(2)
斜率可以通过对测定数据进行线性回归得出，也可以用最优拟合目测法得出。
在一些特定情况下，例如预应力钢筋和钢棒，上述方法不适用时，可在0.05Fm~0.7Fm范围内测定弹性模量。
(3)
除5.3.1规定的要求外，测定弹性模量时，在力值范围内应力速率应保持不变。
6 弯曲试验
6.1 试样
试样应符合第4章规定。
6.2 试验设备
6.2.1 试验设备的弯曲原理如图1所示。
注：图1为弯曲设备的外形构造，可以是芯轴1和支撑2旋转，支座3被固定；也可以是支座3旋转，支撑2或芯轴1被固定。
说明：
1——芯轴；
2——支撑；
3——支座；
D ——芯轴直径。
图1 弯曲设备的原理
6.2.2 弯曲试验也可以按GB/T 232用带有支撑和芯轴的装置来进行。
6.3 试验程序
弯曲试验应在10℃~35℃的温度进行，试样应沿着芯轴进行弯曲。
弯曲角度和芯轴直径应符合相关产品标准的要求。
6.4 试验结果的判定
弯曲试验结果的判定应符合相关产品标准的要求。
当产品标准没有规定时，若受弯曲部位无目视可见的裂纹，则判定该试样为合格。
产生在肋的根部或刻痕上的表面裂缝属于有效试验。裂缝深度应不大于裂缝宽度。
7 反复弯曲试验
7.1 试样
除符合第4章规定外，试样的制备应符合GB/T 238中的相关规定。
7.2 试验设备
试验设备应符合GB/T 238中的相关规定。
公称直径10mm
