Estudo comparativo entre o aço AISI M2 e o aço DIN 50 NiCr13 no processo de conformação a frio

• Autor(a) principal: Gomes, Luciano Silva
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do Mackenzie
• Texto Completo: http://dspace.mackenzie.br/handle/10899/24254
• topic: conformação a frio; deformação plástica; desgaste dos aços; CNPQ::ENGENHARIAS::ENGENHARIA MECANICA

The purpose of this work is to present a comparative performance analysis of two tool steels used for the production of retaining punches, which are part of the cold forming tool of the double locking plate, which makes up the rear seat belt of compact vehicles. The conformation stresses and tool contact pressure were simulated using the Simufact Forming 12 finite element method for all conformation stages, taking the values of the 5th stage whose tooling is the object of this study. The flow limit value determined in this forming operation is about 1500 to 1800 MPa, giving by conversion the minimum value of 54 to 56 HRC for the non-occurrence of plastic deformation. The materials chosen for this investigation were an AISI M2 fast steel and a hot working steel DIN 50 NiCr13. With a minimum of hardness to guarantee the non-occurrence of plastic deformation in the tooling, a cycle of thermal treatments was chosen for the fast steel, aiming at lower hardness levels, within the range 56-58 HRC, for greater toughness, without great damage in terms of wear resistance, which is one of its most striking characteristics. The DIN 50 NiCr13 has received conventional heat treatment, since it is a material less connected to the fast steel, having in general high tenacity, hardness between 54 and 56 HRC. These tools were used in the cold forming process of fasteners in a seven stage progressive horizontal press for cold forming of an AISI 1010 steel supplied in the annealed state. The evolution of the microstructure of the fasteners, AISI 1010, was monitored from its reception and throughout the conformation process, through metallographic analysis and Vickers hardness tests. The microstructure in the receiving state was constituted by particles of cementite dispersed in ferritic matrix of polygonal grains, only showing sensitive variation in the final stages of conformation with the microstructure presenting lines of mechanical deformation. The hardness of the fasteners increased in all cold forming steps. The results in terms of tool performance indicated that AISI M2 steel, despite being thermally treated for a good compromise between hardness (toughness) and toughness, presented mechanical failure after forming about 5 thousand pieces of a batch of 300 thousand pieces The DIN 50 NiCr13 steel, although considered inferior in terms of wear resistance, did not have mechanical failure, which allowed 40 to 50 thousand pieces to be formed.