The present invention discloses a contact method of burn-in and test after packaging. Each ladder section is a hollow rail having different caliber, which can be interconnected by telescoping with each other. A needle shield, which is on the needle within the interior of the catheter hub, is biased axially within the catheter hub with its ends being fixed to prevent axial expansion. A collector vessel may also be included, the collector vessel having an adjustable extension element to modify a resulting entrapment force. 0060, subsequently conducting secondary decarburization refining to a ultra low carbon concentration region while suppressing denitridation using a vacuum degassing facility, then conducting deoxidation by Al and, further, controlling the composition such that mass %Almass %N0.