Investigation of the crack formation in 302HQ austenitic stainless steel bolts during cold forming

• Published in: Tecnologia em Metalurgia, Materiais e Mineracao Vol. 20110718; pp. 1742 - 1754
• Main Authors: De Paula, Joel Jessin Sire, Junior, Jose Mario Fernandes De Paiva, Lapolli, Emerson Luiz, Torres, Ricardo Diego, Junior, Paulo Cesar Soares, L'Hoste, Jeison Sanders, Ganassali, Guido
• Format: Journal Article
• Language: English
• Published: 01.01.2011
• Subjects: Austenitic stainless steels; Cold forming; Cold working; Cracks; Forming; Hardness; Metallography; Screws
• ISSN: 2176-1515

This study investigated the cold forming process of 302HQ austenitic stainless steel fasteners, to identify the causes of crack formation at the edge of the screw head. Was evaluated the material during cold forming, through qualitative metallography and Vickers microhardness, in samples of screws collected over four hours of production, at various stages of forming; and qualitative metallography, scanning electron microscopy (SEM), hardness Rockwell C and measurement of roughness Ra of the forming tools. The results of metallography and microhardness showed a large increase in hardness of the screw head, featuring a high degree of strain hardening. There was also a misalignment in the material flow in this region. Have detected no change in the elapsed time of manufacturing. Tests conducted on the tools showed cracking and failure of adhesion of the coating tool.