Influence of Two Hexavalent Chromium-Free Coating types on Mechanical Behavior of Bolted Joints
Nascimento, H
Fiat Automóveis, Betim, MG, Brazil

Santos, SC
CEFET, MG, Brazil

Sales, WF
Pontifical Catholic University of Minas GeraisPUC Minas Mechanical Engineering, MG, Brazil

Palma, ES
Pontifical Catholic University of Minas GeraisPUC Minas Mechanical Engineering, MG, Brazil

(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, chromium-free coating, clamping force, friction coefficient

Paper ID: JTE12531
DOI: 10.1520/JTE12531

ASTM International is a member of CrossRef.
Author Nascimento, H Affiliation Fiat Automóveis, Betim, MG, Brazil Author Santos, SC Affiliation CEFET, MG, Brazil Author Sales, WF Affiliation Pontifical Catholic University of Minas GeraisPUC Minas Mechanical Engineering, MG, Brazil Author Palma, ES Affiliation Pontifical Catholic University of Minas GeraisPUC Minas Mechanical Engineering, MG, Brazil Author Nascimento H, Santos SC, Sales WF, Palma ES Title Influence of Two Hexavalent Chromium-Free Coating types on Mechanical Behavior of Bolted Joints Symposium , Committee on