抄録
The superiority of hot-workability of consumable electrode arc melted metal is examined by the hot torsion test. The test materials are air-melted AISI 316 stainless steel and its consumable electrode arc-remelted steel. The oxygen content decreases remarkably from 0.0084% to 0.0033% and the Mn content decreases a little from 1.84% to 1.4% by arc-remelting, but other contents show no change. The forgings are solution-treated at 1150°C for 1 hr and water-quenched. All the specimens show the microstructures of austenite, and the results of tensile tests and impact tests at room and elevated temperatures show no difference between the air-melted and the arc-melted specimens, except for the reduction in area of the former is slightly higher than that of the latter. Tensile tests for water-quenched specimens from various temperatures of hot torsion tests, also exhibit the same results as above, and their structures are always of austenite, Hot torsion tests are carried out at 650, 800, 900, 1000, 1100 and 1200°C at the rotation speed of 30 rpm and 128 rpm. Revolutions to failure reach a minimum at 800°C and henceforth increase with rise in temperature, while the maximum torque values decrease gradually. In these tests, the arc-melted specimen, which is almost identical with the air-melted one in tensile properties and structures as mentioned above, indicates higher values than the others in the revolutions to failure, the maximum torque value and the area surrounded by the revolutions-torque curve. These results indicate that the consumable-electrode arc-melted material is superior to the air-melted one in hot workability as well as resistance to deformation at elevated temperatures.
