3.3.2. Tensile Properties of Specimens

To compare the tensile properties of the samples with different carbon contents after laser bionic treatment, the bionic units with the same volume proportions were processed on the surface of the base material. The effect of carbon content on the tensile properties of the biomimetic samples was investigated. Figure 10a–e shows the stress—strain curves of the different carbon-containing untreated samples and laser bionic samples; the corresponding yield strength (YS), tensile strength (TS), and elongation (EL) are shown Table 4.To compare the tensile properties of each biomimetic sample, the tensile property improvement ratio [28] is used to analyze the strengthening effect of different biomimetic samples. The tensile property change ratio refers to the percentage of yield strength, tensile strength, and elongation change of the biomimetic sample compared to the untreated sample, which are represented by *YSC*, *TSC*, and *ELC*, respectively.

**Figure 10.** Tensile curves of bionic samples and untreated samples with different carbon contents: (**a**) A1, (**b**) A2, (**c**) A3, (**d**) A4, and (**e**) A5.


**Table 4.** Tensile test results of the bionic treatment samples and untreated samples.

From Figure 10 and Table 4, it can be concluded that when the carbon content is in the range of 0.15–0.37%, the bionic sample shows a ductile fracture, and when the carbon content is in the range of 0.45–0.58%, the bionic sample shows a brittle fracture. When the carbon content is in the range of 0.15–0.37%, the tensile strength and yield strength of the samples after laser biomimetic treatment are better improved compared to the untreated sample. However, the tensile strength of the bionic samples with carbon content in the range of 0.45–0.58% decreased, especially the tensile strength of the bionic sample with a carbon content of 0.58%, which is even lower than that of the untreated sample.

Figure 11 shows a comparison of the tensile curve of bionic samples with different carbon contents. It can be seen that when the carbon content is between 0.15% and 0.37%, the strength of the biomimetic sample increases, and when the carbon content increases to 0.45%, the tensile strength begins to decline. The elongation of the biomimetic samples decreases continuously with increasing carbon content.

**Figure 11.** Comparative tensile curves of different bionic samples.
