液体ヘリウム温度における極低温構造材料の電磁衝撃破壊

概要

論文の詳細を見る
The present paper describes the electromagnetic impact tests of such cryogenic materials as a Ti-6Al-4V alloy and a 25Mn-5Cr-1Ni steel. The tests were performed in a steady magnetic field of 6 T at liquid helium temperature (4.2 K) by using a newly developed machine. The new impact tester, which is composed of a super conducting magnet, an electric pulse generator and a measuring system, can apply electromagnetic in-plane bending moments up to approximately 1 MN m to a single-edge-cracked specimen. The deformation behavior of the specimen was monitored by a newly designed magnetic pick-up-coil and cryogenic strain gages of the foil type. The transient responses of the deformation rate and strains were obtained by these devices. The critical peak value of the applied current pulse, or the intensity of the applied electro-magnetic force, which causes the fracture or the crack growth, decreased with an increase in fatigue precrack length for the relative precrack length of a/W< 0.5. The critical peak current approached to a constant value for a/W> 0.5 for each material. The value of the critical peak current was 3〜3.6 times higher for the high Mn steel than that for the Ti alloy. This result implies that the high Mn steel has higher resistance to the electromagnetic impact force than the Ti alloy.
社団法人日本材料学会の論文
1988-07-15