There are 16 fixed shapes and sizes from 1 to 14 in the tensile test of stainless steel pipe. The use of these samples depends on the type of material being tested, such as: bar, plate, wire, etc. these standards are specified in JIS. In addition to the tensile strength, the yield strength, specified residual elongation stress, elongation after fracture, reduction of area, etc. can also be detected. The detection method is also specified in JIS.
In JIS standard of stainless steel pipe, the values of these items are specified according to different specifications (Applications). Wire only specifies tensile strength, while structural steel specifies not only yield strength, but also residual elongation stress, elongation after fracture, reduction of area, etc. The stainless steel tube tensile test is to clamp the two ends of the standard sample and slowly stretch until it breaks. It is impossible to ensure the consistency between the sample and the real object, but as long as the sample is produced in large enterprises and the quality management is sufficient, there should be no big difference. Especially after heat treatment, there is no worry about the inconsistency between the material object and the sample.
Tensile strength: the quotient of the tensile force divided by the initial cross-sectional area of the parallel part of the sample, in kg f / mm2. Generally, if f and mm2 are omitted, they are expressed in kg only. 41 in SS41 means his tensile strength is 41kg. (the units and methods of tensile strength are different, such as 41kg in Japan; the international system of units is adopted in China, and the corresponding method is 410mpa or 410n / mm2.
Elongation after fracture: percentage (%) of elongation after fracture to initial length of sample.
Yield strength: in the process of tensile test, there is a stress point where the stress drops suddenly and the specimen is still lengthening under the condition of constant stress. This stress point is called yield strength, which is expressed in kg f / mm2. Generally, F and mm2 are omitted and expressed in kg only. For metallic materials, no greater force shall be applied.
Specified residual elongation strength: except for mild steel, the yield point of other objects is not obvious. It can be expressed by the specified residual elongation stress. That is to say, in the tensile test, although the tensile force is eliminated, the sample can no longer be restored to the original, and the elongation of 0.2% is maintained. Expressed in kgf / mm2. Because of the plastic deformation of 0.2%, this material is no longer available, so this is the limit value.
Reduction of area: the percentage of the maximum reduction of cross-sectional area (the difference between the initial cross-sectional area and the minimum cross-sectional area) and the original cross-sectional area.