1.0.1 This standard is formulated with a view to unifying the test methods of welded joints of reinforcing steel bars, inspecting quality of welded joints and accurately evaluating properties of welded joints.
1.0.2 This standard is applicable to tensile test, bend test, shear test, impact test, fatigue test, metallographic test, hardness test and grain size estimation for welded joint of reinforcing steel bar in concrete structure of industrial and civil buildings as well as general structures.
1.0.3 The test of the welded joint of reinforcing steel bar shall strictly comply with relevant safety operation requirements and be provided with necessary preventive measures to ensure test safety.
1.0.4 The test result shall be deemed as invalid if the test machine affects the test data due to fault or misoperation.
1.0.5 The test of the welded joint of reinforcing steel bar shall not only comply with this standard, but also meet the requirements of relevant current national standards.
2 Terms and Symbols
2.1 Terms
2.1.1 tensile test method for welded joint of reinforcing steel bar
a method for the tensile test of various welded joints of reinforcing steel bars under ambient temperature 10~35℃
2.1.2 bend test method for welded joint of reinforcing steel bar
a method that support roll devices are adopted for the bend test of flash butt welded joint and gas welded joint of reinforcing steel bar
2.1.3 shear test method for resistance spot welded joint of reinforcing steel bar
a method that appropriate special clamping apparatus is selected for the shear test of the resistance spot welded joints in reinforcing steel bar welded frame and welded fabric
2.1.4 Charpy pendulum impact test method for welded joint of reinforcing steel bar
a method that the sample is cut and prepared with a V notch according to the specified center position for the impact test of the welded joint of reinforcing steel bar
2.1.5 fatigue test method for welded joint of reinforcing steel bar
a method that repeated tensile stress is applied on the sample of the welded joint of reinforcing steel bar and S-N curve is plotted to obtain the fatigue limit
2.1.6 metallographic test method for welded joint of reinforcing steel bar
a method that the blank of the welded joint of reinforcing steel bar is made into a sample after cutting, grinding, polishing and corrosion and all zones are subject to macro-observation or micro observation under the microscope
2.1.7 hardness test method for welded joint of reinforcing steel bar
a method that the blank of the welded joint of reinforcing steel bar is made into a sample with smooth plane after cutting, grinding and polishing for the Vickers hardness test according to the set measuring point line
2.1.8 estimating grain size method for welded joint of reinforcing steel bar
a method that the blank of the welded joint of reinforcing steel bar is made into a sample after cutting, grinding, polishing and corrosion for the grain size estimation according to the set measuring point line
2.2 Symbols
2.2.1 Sample dimension symbols
a——the diameter of bending sample;
D——the diameter of bending pressure head;
d——the diameter of reinforcing steel bar;
L——the length of sample;
l——the inside distance between two support rolls;
lh——the weld length;
lj——the clamping length;
ls——the length under test;
S0——the nominal cross sectional area of reinforcing steel bar (wire);
α——the bending angle.
2.2.2 Test symbols of welded joints of reinforcing steel bars
Fj——the shear force of reinforcing steel bar welded frame and welded fabric at welding spot;
Fm——the maximum force;
G——the micro-grain size grade;
HV——the Vickers hardness=constant× test force/surface area of press mark; the front represents hardness value while the rear represents test force value (kgf) and test force retention time (s);
KV2——the absorption energy of V-notch sample under impact of pendulum edge with the radius of 2mm;
Ra——the surface roughness parameter;
ReL——the lower yield strength;
Rm——the tensile strength;
t——the distance between notch centerline and fusion line;
Δσ——the stress amplitude of fatigue test (MPa), i.e., the algebraic difference between high stress and low stress;
ρ——the stress ratio of fatigue test, i.e., the ratio of the minimum stress to the maximum stress;
σn——the conditional fatigue limit, which refers to the maximum stress amplitude (or maximum stress) that the sample structure detail is free from fatigue fracture under the set cycle times.
3 Tensile Test Method for Welded Joint of Reinforcing Steel Bar
3.1 Sample
3.1.1 The dimensions of tensile samples for various welded joints of reinforcing steel bars may be taken according to those specified in Table 3.1.1.
