Investigation on quantitative relationship between angular distribution of laser-processed bionic unit and tensile behavior of 40Cr-steel

Abstract

To investigate the tensile behavior of 40Cr steel, the specimens with varying angular distribution of bionic units were fabricated by laser. Microstructure and micro-hardness of the bionic units were detected. The micro-hardness of bionic unit was remarkably improved, which was more three times as thatofthe untreated specimen. Results of the tensile test demonstrated that there was a major influence on enhancing the strength and plasticity of 40Cr steel due to the existence of bionic units. Meanwhile, there was a downward trend of the yield strength (YS) and tensile strength (TS) of the specimen with the increase of angular distribution (α) of the bionic unit, but the degree of elongation (EL) improvement was enlarged. As compared with that of the untreated sample, the angular distribution (α) of the bionic unit was 0°, the yield strength (YS) as well as tensile strength (TS) of the specimen was improved by 24.77% and 20.73%, respectively. When α was 90°, the elongation (EL) of the specimen was increased by 48.98%. The relation equations of YS, TS, and EL concerning the bionic unit angular distribution were established as follows:yYS=679.69672-0.69754α;yTS=792.82787-0.7959α;yEL=18.48187+0.07372α-0.000393444α2.