Friction Weldability of Grey Cast Iron - by the Concept of Friction Weld Heat Input Parameter -

Abstract

Joining of grey cast iron by fusion welding has much difficulties for its extremely low ductility and low toughness because of the flake form of the graphite. And the brittle microstructure, i.e. ledeburite may be formed during fusion welding by its rapid cooling rates. By these kinds of welding problem, preheat and post heat treatment temperature must be increased to avoid weld crack or welding problems.In order to avoid these fusion welding problem, friction welding of cast iron was carried out for improving joint soundness, establishing friction welding variables.There is no factor for evaluating friction weldability in continuous drive type friction welding. In this point of view,this study proposed the parameters for calculating friction weld heat input. The results obtained are as follows ; 1. There was a close relationship between tensile strength and flash appearance of friction welded joint. 2. Tensile strength was decreased and flash was severely oxidized as increasing frictional heating time. 3. As increased forging pressure P 2 , flash had a large crack and tensile strength was decreased. 4. As powdered graphite by rotational frictional force induced flat surface and hindered plastic flow of metal ,tensile strength of welded joint was decreased. 5. Heat input for continuous drive type friction welding could be calculated by the factors of P 1 , P 2 and upset distance(δ).

Implementation of Exceptional Microstructures and Mechanical Properties of Structural Carbon Steel Tubes by Friction Welding

“…Therefore, among the previously suggested calculation formulas, a calculation formula using the energy conservation law can be used, which can be calculated as the value of pressure and length change before and after welding as follows (Calculation formula (2)). 20,21)…”