Study of contractile strain ratio process capability and performance of Ti-3Al-2.5V tubing for civil aircrafts

High-pressure tubing for civil aircraft Ti-3Al-2.5V hydraulic system is a critical system material. This paper explores from the perspective of improving key production process parameters, by controlling the Q value (wall reduction/inner diameter reduction) in the last three passes of the rolling process of the tubing, the tubing meets the specification requirement of contractile strain ratio (CSR) of more than 1.3 while the preliminary process capability (CPK) is improved from 0.72 to 1.55, and the process performance index (PPK) from 0.66 to 1.44, reaching a level of about 1.33, which basically meets the customer's requirements, with sufficient process capability. Using statistical process control (SPC), combined with the mean-standard deviation (Xbar-S) control charts revealed good data stability.