Mechanical, metallurgical and corrosion analysis of forced cooling assisted laser bending of duplex-2205

Abstract

Laser bending with a small bend angle poses challenges in manufacturing applications. Despite various proposed strategies, the achievable bend angle typically ranges from 0.1 to 2° per scan. This study focuses on enhancing the bend angle of duplex stainless steel by introducing forced cooling (FC). The application of FC aims to reduce the number of scans required, thereby saving time, cost, energy, and controlling material degradation due to excessive heating. The investigation compares the effects of process parameters under natural cooling (NC) and FC conditions. Metallurgical, mechanical, and corrosion properties of the bent specimens are investigated. Results indicate a significant enhancement in the bend angle with FC, showing an improvement of up to 1592 % for specific parameters and sheet geometries. For a 2 mm sheet thickness, the maximum bend angles achieved in five scans are 14.02° and 22.34° under NC and FC conditions, respectively. The influence of process parameters on the bend angle is significantly affected by FC compared to the NC condition. Additionally, the trend of bend angle increment in each scan is almost opposite in FC condition compared to NC. FC results in increased hardness and tensile strength of the bent specimens at the expense of ductility. Microstructural analysis reveals phase rearrangement and grain refinement. Corrosion resistance remains mostly unaffected, although a slight reduction in pitting potential is observed under FC, which is compensated by the formation of a passivation layer. Interestingly, the bend angle achieved in one scan was up to three times higher than the published literature, which could be beneficial for various industries.