Magnetically graduated steel bar

摘要

A magnetically graduated steel bar is provided with a magnetic scale that has a steel composition consisting, on a weight basis, of 0.02-0.10% C, 0.50-1.0% Mn, 0.50-1.0% Si, 17-20% Cr, 5-8% Ni, 0.05-0.20% C plus N, and a balance of Fe and incidental impurities. The steel contains 30-60 vol % of a cold working induced martensite and is given a nonmagnetic austenitic structure by local melting. The steel bar has a tensile strength of at least 130 kgf/mm2 and a fatigue strength of at least 60 kgf/mm2.