An Analysis of the Microstructure, Macrostructure and Microhardness of Nicr-Ir Joints Produced by Laser Welding with and without Preheat

Abstract

This paper discusses some of the basic problems involved in laser welding of dissimilar materials with significant differences in melting points. It focuses on the micro and macrostructure of laser welded NiCr-Ir microjoints used in central spark plug electrodes. The joints were produced by welding with and without preheat using an Nd,YAG laser. The structure and composition of the welded joints were analyzed by means of a light microscope (LM) and a scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) spectrometer. The microhardness of the weld area was also studied.

Identifying the cause of cutting tool failure by using simulation software

“…Fig. 3 describes the output of simulation focused on the size of movements from each parts of the tool during cutting by the first assembly of punchers with bigger length [2,5,7,9].…”

“…Fig. 5 represents the result of simulation focused on the movement of tool parts during cutting with the same height of the punchers at two times bigger load (2600 kN) [5,7,9].…”

“…In this case, from the conception of the used press, it is not possible to reach this method. That means there had to be proposed another solution [2,5,7]. Next way how to decrease the maximal cutting force and to secure the resultant force effect in the middle is to grind the punchers under defined angle (Fig.…”

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“…a half. Low plastic properties of copper in this solidifying interval create a possibility of cold cracks [11,12].…”

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“…When the laser beam impacts the cut material, a mutual interaction occurs between the cut material and the beam itself. The subsequent phenomena, occurring during the material cutting, which are affecting the properties of the material after the impact of the focused beam, depend, in particular, on the chemical composition of the cut material and on the quality of its surface [1,6,7].…”