Possibility of replacing low-carbon structural steel with high-strength steels, for producing welded structures in industry of heavy machines

Abstract

Modern trends of research and development of new products are focused on saving materials through mass reduction of various parts, so the high-strength steels (HSS) are used more often than conventional low-carbon structural steels. It is well known that high strength of HSS is providing a possibility for parts to be produced with smaller dimensions and crosssections. This often results in decreasing in weight of parts and whole structures. In this paper possibility for replacing commonly used, low-carbon, structural steels which have good weldability, with HSS, in industry of heavy machines is analysed. Main goal of this replacement is weight reduction as well as to keep adequate load capacity and reliability of parts and structures. Properties of three structural steels were analysed: Č0562 (S355J0), ČRO460 (P460NL1) and STRENX 700 (S690QL). Furthermore, both advantages and disadvantages of HSS application, complexity of choosing the correct welding method, correct filler materials and favourable welding technology are indicated. After the trial welding on samples, experimental investigation of important mechanical and microstructural properties such as strength, plasticity, impact toughness, hardness and microstructure evaluation were conducted. Based on the obtained experimental results the specific conclusions were given.