Détermination de la forgeabilité des métaux et alliages¹

Forging limit determination of metals and alloys

¹ Université de Valenciennes et du Hainaut Cambrésis, Laboratoire de Génie Mécanique, GRECO Grandes Déformations et Endommagement, Mecamat
² GIAT/ATS, Centre de Recherches des Matériaux, Tarbes

Abstract

Physical defects which occur during forging processes are reviewed and up to date predicting models are discussed.

Three specific tests are presented for the accurate determination of forging limits : notched cylinders tension tests, compression tests and collar tests.

Strain and stress calculated values near the fracture occurence sites are used to plot forging limit curves in terms of local strains first, and second, intrinsic forging curves in terms of local strains and mean local stress-equivalent local stress ratios. The forging limit curve is found to be rather approximative, the intrinsic forging curve gives a more accurate prediction.

A lot of examples are presented and the efficiency of intrinsic forging curve concept is demonstrated : when mechanical models, either with analytical or numerical treatment, are available, and intrinsic forging curves defined, the defects occurence may be strongly reduced in most forging operations.