Low‐Temperature PVD TiAlCrSiN Coated High‐Speed Steel: Comparison between shot peened and polished substrate condition

In order to increase tool life of fine blanking punches, this work investigates a combined solution approach consisting of increasing the mechanical strength of the substrate material by shot peening and deposition of PVD hard coatings. A powder metallurgical high-speed steel is used as substrate material. First, the temperature-dependent relaxation behavior of residual stresses and strain-hardening of the shot peened substrate is analyzed. Subsequently, the coating process for deposition of the wear-resistant hard coating TiAlCrSiN is adjusted regarding the substrate temperature to prevent the heat input from causing significant relaxation of the shot peening effects. After shot peening, the substrate exhibits an increased hardness of ΔHIT ≈ +10 % and compressive residual stresses of σ ≈ –1,700 MPa. Significant relaxation after heat treatment occurs between T = 300 °C and T = 400 °C. Thus, the substrate temperature does not exceed TS ≈ 300 °C during coating deposition due to process adjustments. Shot peening leads to an increased substrate and coating roughness as well as a slightly higher indentation hardness of the TiAlCrSiN coating. Moreover, the coatings deposited on shot peened substrate exhibit enhanced adhesion strength to the substrate and improved impact resistance. Shot peening and coating application by physical vapor deposition (PVD) can provide increased wear resistance to tools of high-speed steel (HSS). However, high heat input of coating processes lead to relaxation of previously induced compressive residual stresses and strain-hardening. TiAlCrSiN coatings deposited at reduced substrate temperature reveal improved adhesion strength and impact resistance on shot peened HSS substrate compared to polished HSS substrate. This article is protected by copyright. All rights reserved.