Study on the influence of reduction on mechanical properties and the structure of C1 lead narrow strips during cold rolling

The article describes the results of experimental rolling of narrow strips from lead alloy C1 on two-high rolling mill 130×10. The authors studied changes in mechanical properties and the material structure in the original annealed state and after six passes of narrow strips, 10 mm wide, from a thickness of 2 mm to 0.9 mm. It has been determined that every pass at an increase in percentage reduction from 30 to 50–55% entails changes in mechanical properties and the material structure. Hardness and strength in the original state are minimum (13 HV, σв = 1.09 MPa), and ductility are maximum (percentage elongation δ = 25 %, percentage reduction of area ψ = 54 %). The grain shape in the material structure is spherical, the size is about 3 μm. Changes in mechanical properties were studied in every pass of six passes of rolling narrow strips. It has been showed that after the latest pass at a total reduction of narrow strips of 50–55% hardness and strength increased (51 HV, в = 1.56 MPa), and ductility decreased (percentage elongation δ = 17.6%, percentage reduction of area ψ = 23.15%). The material structure contains directional texture coinciding with the rolling direction. The grain shape of narrow strips exiting the rolling mill became elongated with a length-width ratio of 2:6 μm. The studies result in obtaining curves and linear regression equations applied to determine crossing relations between changes in strength and ductility properties in the original state and after every pass of six subsequent rolling passes. The results and regularities obtained are used for nondestructive testing of mechanical properties of flat products and adjustment of rolls of rolling mill 130×10 at the mechanical engineering plant, Bogorodsk Branch of JSC Scientific and Production Association Pribor, to improve the quality of narrow strips from alloy C1.