Fabrication of high-power diesel engine crankshafts by electro-slag casting process

Abstract

The electroslag remelting (ESR) technology combined with a set of shaped water-cooled metal moulds, a large-scale crankshaft of 16V280 diesel engine was manufactured directly from the ESR molten metal by a single step process. The crankshaft has a more compact structure than that by forging and no casting defects found, such as gas holes and cracks, etc. The crankshaft casting made by ESC (electroslag casting) weighs about 3.3 tonnes, which is only about half of the forged crankshaft. The crankshaft has been put into operation in a DF 11 locomotive for more than 24,000 h, and has a quite good performance. The element weight loss and distribution of 42CrMo steel during electroslag remelting were investigated. The results show that C, Si, Mn slightly reduced. The maximum loss of carbon and silicon are both about 0.01% and that of the manganese is about 0.02%. The contents of other elements, such as Cr, Mo, Cu, have nearly no changes. The result also shows that the casting has an even element distribution from the bottom to the top. The chemical composition can be easily controlled within the required specification by adjusting the composition of the melted electrode. ESR process can effectively remove the harmful elements: sulphur, phosphorus, inclusion and gas. It reveals that oxide inclusions and sulfide dropped from 0.0065% and 0.014% to 0.0045% and 0.006%, respectively. And 96% Fe 2O 3 and 57% sulfide were removed. Sulphur was reduced from 0.010% to 0.0033%. The oxygen and nitrogen content were reduced about 20% and 37%. ESC process increased the density of the casting slightly, decreased the porosity defects obviously.