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Abstract This paper presents the failure analysis of the lead-free brass valve bodies that had been installed in plumbing sanitary equipment. Leakage points were found adjacent to the brazing location. Visual inspection, stereomicroscope and scanning electron microscopy coupled with an energy dispersive spectrometer (SEM/EDS) were used as the principal analytical methods for the present failure analysis. The analysis results implied that the combined action of excessive brazing residual stresses and bismuth boundary segregation was probably responsible for the failure of lead-free brass valve bodies. Finally, two important suggestions were proposed to minimize the risk of recurrence of the present leakage failure in the future. Highlights • Investigation on the leakage failure of the lead-free brass valve body is performed. • Macro and micro morphology observations and EDS analysis were carried out. • The failure was probably attributed to the combined action of brazing residual stresses and bismuth boundary segregation. [ABSTRACT FROM AUTHOR]

In this case study, the failure cause of a lead-free brass tap was investigated. The features of cracks were carefully studied by macroscopic inspection, chemical analysis, optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The analysis results showed that the micro segregation of bismuth in the failed lead-free brass tap was considered as an important reason for crack formation. Further examination indicated that coarse bismuth rich phases were distributed mainly along grain boundaries. The cracks were found to be a typical intergranular failure, which revealed brittle fracture for the failed lead-free brass tap. It is expected that this work may help reduce the incidences of failures during the productive process of the lead-free brass taps. [ABSTRACT FROM AUTHOR]

Hot compression tests were carried out to study the deformation behaviors of a lead-free machinable brass using Gleeble-1500 thermal simulator in the temperature range of 823-973K and the strain rate range of 0.01-10 s. The results show that the flow behavior of the lead-free machinable brass is strongly influenced by strain rate and temperature, and the flow stress increases with increasing strain rate and decreasing temperature. The constitutive equations incorporating the effects of strain rate and temperature have been established to model the hot deformation behavior of this alloy. The reliability of the developed constitutive model was demonstrated by the mean percentage error of 10.82 % and the correlation coefficient of 0.98. Moreover, the flow stability/instability of the lead-free machinable brass was carefully investigated on the basis of dynamic material modeling approach. It was found that plastic deformation was stable for processing conditions in which the strain rate range was 1-10 s within the temperature range of 823-923 K. [ABSTRACT FROM AUTHOR]

Abstract: The effects of room-temperature deformation on mechanical properties, the microstructure and texture evolution of continuous columnar-grained BFe10-1-1 cupronickel alloy tubes during room-temperature rolling and drawing were investigated. The results showed that continuous columnar grains were gradually thinned down into fiber microstructure, and the degree of working-hardening of the BFe10-1-1 alloy was increased continually with the increase of room-temperature reduction during rolling and drawing. After the rolling deformation degree of 82.8%, the ultimate tensile strength (UTS) of the BFe10-1-1 cupronickel alloy tubes increased to 418.7MPa from 212.0MPa of the as-cast state, and the elongation (El) of 8.5% was still obtained. The as-rolled BFe10-1-1 cupronickel alloy tubes were further drawn to the deformation degree of 99.0%, and the ultimate tensile strength (UTS) increased to 603.7MPa and the elongation (El) reduced to 2.2%. The excellent room-temperature extensibility of the continuous columnar-grained BFe10-1-1 cupronickel alloy tubes is significantly beneficial from the relative high volume fraction of the <100> texture as well as low angle boundary. [Copyright &y& Elsevier]

Abstract: Isothermal compression tests were carried out on Al6061 using a Gleeble-1500 thermal simulator at temperatures ranging from 573 to 723K and strain rates from 0.5 to 30s−1. The flow stress of Al6061 was characterized based on an analysis of the true stress–true strain curves. A mathematical mode coupling flow stress with strain, strain rate and temperature for Al6061 has been proposed by using a hyperbolic sinusoidal type equation. The material constant α is 0.01MPa−1 in the model, whereas other material constants n, lnA and Q are found to be functions of strain. The predicted results from this proposed model are found to be in good agreement with the experimental flow stress curves which can be used to predict the required deformation forces in hot deformation processes. [Copyright &y& Elsevier]