No abstract

This paper aims at encouraging the use of laser treatment as an environmentally friendly technique to improve the mechanical properties of metallic materials over conventional quenching and tempering techniques through the study of the tribological behavior of AISI 1538 MV steel subjected to surface laser quenching treatment. Sliding wear tests were carried out by the pin-on-disk method. In order to identify the wear mechanisms, the worn surfaces on the disks were evaluated by scanning electron microscopy and the wear scars on the ball were observed by optical microscopy. Results reveal that laser treatment reduces the average friction coefficient by 25% and the wear rate by 60% compared with those achieved by the conventional methods, while the depths of the wear track and hardness of the cross section and surface are maintained.

Simulations of impact events in the automotive industry are now common practice. Vehicle crashworthiness simulations on plastic components cover a wide range of strain rates from 0.01 to 500 s-1. Because plastics mechanical properties are very dependent on strain rate, developing experimental methods for generating stress-strain curves at this strain rate range is of great technological importance. In this paper, a modified Charpy machine capable of acquiring useful information to obtain the stress-strain curve is presented. Strain rates between 300 to 400 s-1 were achieved. Three thermoplastics were tested: high-density polyethylene, polypropylene-copolymer and polypropylene-homopolymer. Impact simulations using LS-DYNA were performed using the acquired high-strain rates stress-strain curves and compared with experimental data. Simulations using stress-strain curves from quasi-static tests were also performed for comparison. Very good agreement between the simulation and experimental results was found when the ASTM D1822 type S specimen was used for testing each material.