Prof.dr.ing. Viorel Micloşi

 

Abstract

After a brief presentation of some old ideas concerning the martensitic points temperatures, Ms and Mf, and the factors influencing these temperatures, especially in the heat affected zone, are in discussion. The significant effects of the austenitization temperature and of the cooling rate on these temperatures are underlined. As a result of these effects, the changes in the dynamics of the martensitic transformation in the heat effected zone (HAZ) are evinced. These are in correlation with accumulated hydrogen in the neighbourhood of the fusion zone zone and the increasing of the residual austenite percentage. It is evinced the necessity to correlate the preheating temperature and the interpass temperature with the real values of the Ms and Mf temperatures, corresponding to the heat affected zone, not with the same temperatures with the real values material. This hypotesis is valid in the case of the alloyed steels subjected to the post welding heat treatments. Also, it must be specified that beginning and the ending zones of the long layers, and the short layers (the repairing layers by welding) are critical, taking into consideration all above mentioned.