Influence of Chemical Composition and δ-ferrite on Hot-Cracking in Cu Bearing 18-8 Stainless Steel

Abstract

Cu bearing 18-8 stainless steels are well known to be liable to cracks by hot working. In order to investigate the effects of chemical composition and metal structure on the hot cracking, hot upsettingtests were carried out.
The results are summarized as follows.
(1) Many cracks were found above 4% of copper content, but a few cracks, below 4%.
(2) In the case of 2% of copper content, cracks tended to decrease with the decrease of chromiumcontent and the increase of nikel content.
(3) Cracks propagated mainly along δ-ferrite, and cracking tendencies were estimated by Nibalanceand the amount of 5-ferrite in the as-cast state.