Investigation of Hot Extrusion-caused Cracking of Inconel 718 Seamless Steel Tube and Related Control Measures

Analyzed here in the essay are the cracks as occurring on the surface of the Inconel 718 seamless steel tube during the hot-extrusion process, and the causes by means of the SEM, EDS and the optical metallographic microscopy, etc.As a result, it is identified that high heating temperature on the surface of the blank and the high hot-extrusion speed lead to the said cracking.Accordingly relevant corrective actions are taken, including increasing the pre-heating time, properly reducing the hot-extrusion temperature, and slowing down the extrusion speed, which have brought about satisfactory surface quality of the Inconel 718 seamless steel tube as hot-extruded in lots.