Effect of heat treatment temperature on microstructure and mechanical properties of semi-solid extruded tin bronze

Abstract:

The semi-solid extruded ZCuSn10P1 tin bronze was used as the research object. The effects of heat treatment temperature on microstructure and mechanical properties of semi-solid extruded tin bronze were investigated by using optical microscopy, scanning electron microscopy, microhardness test, Brinell hardness test, tensile test machine. The results indicate that the heat treatment has a great effect on the strength, hardness and microstructure of semi-solid extruded tin bronze. With the heat treatment temperature increase from 250℃ to 650℃, the tensile strength of tin bronze increases first and then decreases, the elongation increases, the Brinell hardness increases first and then decreases. The Vickers hardness of the solid zone and solid-liquid interface increases, however, the liquid zone decreases. The average grain size of solid phase increases, while it is not spherical but rose-like with the temperature increases up to 650°C. With the increase of temperature, the element contents of Sn and P in the solid phase increase, and element segregation weakens. The comprehensive mechanical properties of tin bronze at heat treatment temperature 350°C for 120 min are fine. At this time, the tensile strength is 402 MPa, elongation is 4.5%, Brinell hardness is 136 HBW, compared with before heat treatment, it increases by3.88%, 60.71%, and 6.25%, respectively.

Key words:Copper alloy; semi-solid extrude; heat treatment; microstructure evolution; mechanical properties