Influence of scratch type on tensile strength in in situ tensile test

In this article, the specimen of Q235 (low carbon steel, C ≤ 0.22%, Mn: 0.3%–0.8%, Si ≤ 0.3%, P ≤ 0.045%, S ≤ 0.05%) has been tested in in situ tensile tests. Especially, different types of scratches are prefabricated with 1, 2, and 3 µm in depth. In addition, three scratch angles (θ = 0°, 45°, and 90°) are adopted to explore the changes of tensile strength. The cross profile of the scratch groove is measured with in situ observation method (Olympus DSX500), which is taken as an important indicator to verify the experiments. According to the results of experiments, scratch depth and angle can influence the tensile strength of material. When the depth and scratch angle increase, there is a decrement in the value of tensile strength. This indicates that the surface damage really has effect on the tensile strength of specimen.