Performance testing is an important part of steel standardization. Given the small amount of information gathered in this section, we will introduce some definitions of testing items, testing methods, and testing standards. In this period, we first introduce the common performance indicators on the warranty book: yield, tensile, extension, n value, r value, bending. Yield Strength When the metallic material exhibits a yielding phenomenon, a stress point at which plastic deformation occurs without increasing the force is reached during the test. The upper yield strength and the lower yield strength need to be distinguished. Its marking material changes from elastic deformation to plastic deformation. For materials with continuous yield characteristics, the yield strength is usually expressed as Rp0.2. Summary of detection methods The static axial tensile test method is used to calculate the test according to the load corresponding to the characteristic point divided by the original cross-sectional area of ​​the sample at room temperature. An extensometer that measures the elongation of the sample is also required to detect Rp0.2 and Rt0.5. Testing standard GB/T 228.1, ISO 6892-1, ASTM A 370, ASTM E8/E8M, JIS Z 2241, and the like. Note: tensile strength The maximum engineering stress that the specimen can withstand before being fractured. Used to characterize the resistance of a material to maximum uniform plastic deformation. Summary of detection methods The static axial tensile test method is used to calculate the maximum force during the tensile test divided by the original cross-sectional area of ​​the sample at room temperature. Testing standard GB/T 228.1, ISO 6892-1, ASTM A 370, ASTM E8/E8M, JIS Z 2241, and the like. Elongation after break The elongation after fracture is a plasticity index of the material and is the ability of the specimen to undergo plastic deformation from tension to fracture. The residual elongation of the gauge length after the break is calculated as a percentage of the original gauge length. Summary of detection methods Testing standard GB/T 228.1, ISO 6892-1, ASTM A 370, ASTM E8/E8M, JIS Z 2241, and the like. Yield point elongation When the sample with discontinuous yield is pulled to the yield stage, the elongation of the sample is not accompanied by the increase and decrease of the load. A zigzag-shaped platform appears on the stress-strain curve, and the yield point elongation is used to evaluate the platform. The length of the. Summary of detection methods The percentage of the extension of the gauge length of the extensometer to the original gauge length of the extensometer between the start of yielding and the start of uniform work hardening was measured by means of a static axial tensile test at room temperature. Testing standard Strain hardening index (n value) The n value is a work hardening index or a strain hardening index for evaluating sheet metal forming properties. Summary of detection methods Testing standard Plastic strain ratio (r value) Detection method summary The static stretching method is used to detect the r value. Usually, the sample is stretched to a certain specified strain within the uniform strain range, and the sample gauge length and width value before and after the stretching are measured and calculated. The gauge length and width can be measured either manually or automatically. The automatic method requires an extensometer in both directions. Testing standard bending Test Method Summary The bending test is subjected to bending plastic deformation on a bending tester in a circular, square or polygonal specimen until the specified bending angle is reached and then the crack in the curved region of the specimen is evaluated. Testing standard postscript: Electronic Sample Impact Notch Machine Electronic Sample Impact Notch Machine,Electronic Notch Machine,Notch Prototyping Machine,V Notch Sample Machine Dongguan Best Instrument Technology Co., Ltd , https://www.dgbestinstrument.com
1. The maximum stress before the first drop of the force yield curve of the upper yielding ReH sample;
2. The minimum stress when the lower yielding ReL does not count the initial transient effect during the yielding period;
3. The plastic stress of Rp0.2 is equal to the corresponding stress of the gauge length of the extensometer.
4. The total extension of Rt0.5 is equal to the corresponding stress at the specified gauge length of the extensometer.
Note: When the upper yield strength is higher than the tensile strength, the tensile strength usually refers to the maximum engineering stress after the upper yield.
The static axial tensile test method is used to stretch the sample to break at room temperature. The tester obtains the original gauge length and the post-break gauge length of the sample, and obtains it by calculation. It can also be measured by means of an extensometer and calculated.
Note: Non-proportional samples are usually used.
GB/T 228.1, ISO 6892-1, ASTM A 370, ASTM E8/E8M, JIS Z 2241, and the like.
Using the static axial tensile test method, the stress-strain data of the specimen within the uniform plastic deformation range after yielding, or the stress-strain data within a range of uniform plastic deformation at room temperature, in the double logarithmic coordinate plane Find the slope of the relationship curve.
GB/T 5028, JIS Z 2253, ASTM E646, etc.
The ratio of the actual strain in the width direction of the thin plate sample to the actual strain in the thickness direction during uniaxial stretching. Its size reflects the difficulty of thickness deformation during sheet metal forming.
GB/T 5027, ASTM E517, JIS Z 2254, etc.
A test method for determining the ability of a metal material to withstand bending plastic deformation.
GB/T232, JIS Z 2248, etc.
Different test methods are available for different products, which can be seen in the standard number corresponding to the performance we introduced today. Taking the JIS standard as an example, the yield, the tensile, and the extension are all in JIS Z 2241, and the bending is in JIS Z 2248, and the standard values ​​corresponding to the n value and the r value are also different.