ВЛИЯНИЕ ТЕМПЕРАТУРЫ НАГРЕВА ПОД ШТАМПОВКУ НА СКЛОННОСТЬ К РАСТРЕСКИВАНИЮ ЗАГОТОВОК ИЗ ЛМцАЖН 59-3,5-2,5-0,5-0,4

Abstract

Since the cause of the delayed destruction of the two-phase brasses is not fully determined, the commercial supplies of semi-finished products have unstable technological properties. As the result of experimental work, the author obtained the contradictory data on the root cause of cracking and the influence of grain growth during heating on the crack formation tendency. Meanwhile, the current requirements to the technological processes need the maximum loss minimization during the mill products processing. The paper covers the issue of the selection of temperature intervals of hot plastic deformation to eliminate and determine the relationship between the β-phase grain size and the cracking carried out on the basis of industrial experiment followed by the comparative metallographic analysis of batches with different handling properties. For this purpose, the author carried out the comparative industrial experiment between the batches with different handling properties, determined the actual temperature of hot deformation, and performed the controlled forging at different heating temperatures. The subsequent metallographic analysis proved the assumption that the increase in the forging temperature can increase the level of deviations in some cases and reduce in the others. The author studied the influence of the initial microstructure of the CuMnAlFeNi 59-3.5-2.5-0.5-0.4 alloy, the heating temperature of forging by the level and the type of defects of work material for the blocking synchronizer rings made of different batches of tubes. It is determined that the conditions for the production of pipes are the more significant factor for cracking than the heating temperature at the certain interval. When heating up to 780 °C, the large grains are formed in the individual batches that may be caused by the initial β'-phase grain texture but is not the root cause of destruction. When heating up to 700 °C, the high dispersion silicides do not dissolve, what may cause the origination of hidden cracks during forging. The optimum heating temperature is 750 °C.