ISSN: 1945-7553
CODEN: JTEVAB
Published Online: 30 March 2005
Page Count: 6

Influence of Two Hexavalent Chromium-Free Coating types on Mechanical Behavior of Bolted Joints

Nascimento, H
Mechanical Engineer, Fiat Automóveis, Betim, MG

Santos, SC
Professor, CEFET, MG

Sales, WF
Professor, Pontifical Catholic University of Minas Gerais—PUC Minas—Mechanical Engineering, MG

Palma, ES
Professor, Pontifical Catholic University of Minas Gerais—PUC Minas—Mechanical Engineering, MG

(Received 31 December 2003; accepted 15 December 2004)

Abstract

The goal of this work is to evaluate the performance of two different coating technologies for bolts. They are based on zinc and aluminum with no hexavalent chromium in their composition. These technologies were implemented because international laws for environmental and human health protection are limiting the use of the hexavalent form of chromium because it causes different cancer types in workers, mainly in recycling processes. The experimental tests were performed using M12x1.25–10.9 bolts that were submitted to the test of torsion-tension. The clamping load, total torque, torque on thread, torque on the bolt head, and twist angle were measured. The friction coefficients between the nut and bolt threads, between the face of the nut and its bearing surface, the global coefficients of friction, and the nut factor were also measured and analyzed.

Keywords:
bolt coating, bolted joints, friction coefficient, clamping force

Paper ID: JTE12531
DOI: 10.1520/JTE12531
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