Metodologia básica para a produção de materiais de referência para a calibração indireta de máquinas pendulares de impacto Charpy.

The methodology presented in this work, even if in a plenty way “basic”, it represents an unpublished action in the Brazil of promoting a scientific study for production of reference materials addressed to the mechanical tests, especially, to the tests of impact of the type Charpy. This research line to the moment it is just followed by INMETRO/IPT (CRUZ et al., 2006) that doesn't still dispose of practical results. The studies facts for them approached the techniques and the difficulties of specimen making mainly removed Charpy of laminated foils of the steels ASTM A36 and APIX65 supplied by USIMINAS. In this work opted goes to comparative study and analyses of the mechanical characteristics and chemistries of the materials of reference of low and high level of impact energy - SRM 2092 and SRM 2096 (NIST, 2000) in relation to the steel AISI/SAE 4340, chosen goes the making of the specimens. Unhappily, the steel AISI/SAE 4340, was not found in the internal industry with the form and recommended dimension–bar of steel with squared traverse section of 14mmx14mm (9/16”x9/16”) (ASTM E 1271-94, 1994). But the found results being used specimens removed of bars of steel AISI/SAE 4340, traverse section to circulate with 15,875mm (5/8”) of diameter they were compatible. The deviations in the impact energy Charpy of CPs produced in relation to the materials of reference of NIST although validated by statistical methods, they didn't assist the strips of acting acceptance specified in norms completely. Consequently, the methodology proposal should be improved after a technical investigation of the responsible agents by the variations obtained in the results of the accomplished tests.