Determination of polynomial depending between hardness and cooling time t8/5 of steel NIONICRAL 70 heat affected zone

Abstract

Because of the high heating and cooling velocity values, welding procedure is an unstable process. During welding, changes in microstructure are occurring under overheating and/or cooling conditions. In comparing to the parent steel (PM), throughout welding of steel alloys, a whole series of complex processes are performed which influence to the appearance of different weldments microstructure and at the level of stresses in the weld metal (WM) and the heat-affected zone (HAZ). In present paper, the analytic dependence between Vickers hardness (HV) values and cooling time im temperature interval from 800C to 500C (t8/5) will be determined using the test results of experimental investigation of NIONICRAL 70 (NN-70) steel.