Effect of Preheating on the Structure and Mechanical Properties of Steel S1300QL

Abstract

The use of advanced structural materials entails the necessity of adapting typical welding processes to special requirements resulting from the limited weldability of new materials, often tied to their complex chemical composition or unique mechanical properties obtained in technological processes used in the production of steels and alloys. An example of steel characterised by limited weldability is steel having a guaranteed yield point of 1300 MPa, where such high strength is obtained by adding slight amounts of carbide-forming elements and using complex heat treatment processes. As a result, not only a heat input accompanying the process of welding but also any additional procedures connected with the pre-weld preparation of edges or preheating could adversely affect the above-named properties. The tests described in the article involved the simulation of preheating combined with various cooling conditions. The tests enabled the identification of a permissible temperature, at which no unfavourable changes took place as well as the determination of critical temperatures, the exceeding of which could significantly alter mechanical properties.