Low-Temperature Physical Vapor Deposition TiAlCrSiN Coated High-Speed Steel: Comparison Between Shot-Peened and Polished Substrate Condition

To increase the 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 physical vapor deposition (PVD) hard coatings. A powder metallurgical high-speed steel (HSS) is used as a 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 Delta H (IT) approximate to+10% and compressive residual stresses of sigma approximate to-1700 MPa. Significant relaxation after heat treaent occurs between T = 300 and T = 400 degrees C. Thus, the substrate temperature does not exceed T (S) approximate to 300 degrees C during coating deposition due to process adjusents. 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.