Antonio Carlos Canale

Water and Polymer Quenching of Aluminum Alloys: A Review of the Effect of Surface Condition, Water Temperature, and Polymer Quenchant Concentration on the Yield Strength of 7075-T6 Aluminum Plate

Cold water is perhaps the most common quenchant used for heat treatable aluminum alloys. In many situations, excessive distortion and cracking problems require the use of a less severe quenchant such as hot water or a Type I aqueous polymer quenchant. However, when these alternative quenching media are used, the distortion improvement achieved is typically accompanied by a corresponding loss of strength. This paper will provide an overview of cold versus hot water quenching and the potential use of Type I polymer quenchants. The potential use of quench factor analysis to aid in quenchant media selection and corresponding property prediction is reviewed and applications are demonstrated. The often dramatic impact of the surface condition of aluminum on quenching performance and properties achieved will also be included in this review.

Overview of factors contributing to steel spring performance and failure

Leaf springs and coil springs are commonly used in the motor vehicle industry. Premature fatigue failure is a common failure mode. However, the reasons for these failures may be more complex and include: design deficiencies, heat treatment, steel alloy chemistry, intergranular cracking, presence of Fe-S inclusions, and grain boundary embrittlement. This paper will provide an overview of spring steel: chemistry, heat treatment, residual stress, fatigue failure, and failure analysis of leaf and coil springs.

Analysis of emergency braking performance with particular consideration of temperature effects on brakes

During vehicle deceleration due to braking there is friction between the lining surface and the brake drum or disc. In this process the kinetic energy of vehicle is turned into thermal energy that raises temperature of the components. The heating of the brake system in the course of braking is a great problem, because besides damaging the system, it may also affect the wheel and tire, which can cause accidents. In search of the best configuration that considers the true conditions of use, without passing the safety limits, models and formulations are presented with respect to the brake system, considering different braking conditions and kinds of brakes. Some modeling was analyzed using well-known methods. The flat plate model considering energy conservation was applied to a bus, using for this a computer program. The vehicle is simulated to undergo an emergency braking, considering the change of temperature on the lining-drum. The results include deceleration, braking efficiency, wheel resistance, normal reaction on the tires and the coefficient of adhesion. Some of the results were compared with dynamometer tests made by FRAS-LE and others were compared with track tests made by Mercedes-Benz. The convergence between the results and the tests is sufficient to validate the mathematical model. The computer program makes it possible to simulate the brake system performance in the vehicle. It assists the designer during the development phase and reduces track tests.

Development and Use of a Small Laboratory Intensive Quenching (IQ) System

Intensive quenching (IQ) has been defined as “those quenching conditions that lead to uniform maximum surface compressive stresses,” which provide maximum surface compressive stresses with correspondingly optimized distortion control. An earlier paper described the design and construction of a laboratory system that provides sufficient heat transfer rates to be classified as an IQ system. This paper describes the experimental work conducted with this laboratory IQ system. Particular focus will be on construction and use of this laboratory device to quench SAE 5160 spring steel under IQ conditions and the corresponding cooling curves, heat transfer rates, and compressive stresses obtained.

Modeling of Hardness of Low Alloy Steels by Means of Neural Networks

The tempering process aims to get the microstructures that lead to service mechanical properties and to promote the relaxation of the residual stresses generated during quenching. The goal of this work is to predict the effect of tempering time and tempering temperature on hardness by means of neural networks (NNs). Five types of steels, SAE 4140, SAE 4340, SAE 5160, SAE 6150, and SAE 52 100, were tempered in different conditions. The inputs of the NNs were the chemical composition, the tempering time, and tempering temperature, while hardness was the output. The selected temperatures were 100, 150, 200, 250, 300, 400, 500, 600, and 700°C. The time on each temperature was 10, 90, 900, 3600, 9000, and 86 400 s. Many architectures were tested, until the best one that fitted the data was found. To evaluate this NN the correlation coefficient (R value) was calculated and an analysis of variance test was performed.

Influencia de los Parámetros de Carga en la Estabilidad Direccional de un Vehículo Combinado

This work is about the directional stability of truck-semitrailer vehicle, commonly used in Brazil, as a function of load parameters. For different positions of centre of gravity of semi-trailer, the curves that represent the characteristic movements and the ratio of damping for these movements during curved and straight trajectories are obtained. The influence of load and moment inertia variations for different adopted positions of the centre of gravity of semi-trailer was calculated. The results show significant changes on dynamic response of vehicle with the variations of load parameters. Thus, the operating conditions with less safety margins were determined, so they can be avoided by users. The study allows concluding that there are load conditions that although being accepted by the present legislation, must be avoided.