Abstract: A method of and apparatus for nondestructive testing of spot welds by producing in a test weld high and low frequency electromagnetic fields to induce eddy currents in the weld zone. The difference between the phase values of the resultant electromagnetic field intensities is indicative of the quality of the weld. The apparatus includes an eddy current transducer, high and low-frequency measuring channels, an indicator, and a controlled commutator for alternate connection of the eddy current transducer to the low-frequency measuring channel or to the high-frequency measuring channel. A memory unit is provided for storing the output signal of the high-frequency measuring channel, and a comparator is provided for comparing the signal stored in the memory unit with the output signal of the low-frequency measuring channel.

Abstract: A corrosion-resistant weldable martensitic steel essentially consists of carbon 0.06 to 0.10 weight percent, chromium 15.1 to 16.5 weight percent, nickel 3.5 to 4.45 weight percent, silicon 0.10 to 0.60 weight percent, manganese 0.20 to 0.50 weight percent, at least one element selected from the group consisting of niobium 0.25 to 0.40 weight percent and zirconium 0.05 to 0.20 weight percent, at least one element selected from the group consisting of yttrium 0.05 to 0.20 weight percent, cerium 0.05 to 0.15 weight percent and lanthanum 0.05 to 0.15 weight percent, phosphorus not exceeding 0.025 weight percent, sulfur not exceeding 0.02 weight percent, copper not exceeding 0.20 weight percent, the remainder being substantially iron and unavoidable nonferrous impurities. The process for the manufacture of the steel comprises the steps of preparing a molten mass of said composition, pouring the molten mass into a mould and permitting it to solidify therein followed by cooling an ingot produced.

Abstract: A corrosion-resistant weldable martensitic steel essentially consists of carbon 0.06 to 0.10 weight percent, chromium 15.1 to 16.5 weight percent, nickel 3.5 to 4.45 weight percent, silicon 0.10 to 0.60 weight percent, manganese 0.20 to 0.50 weight percent, at least one element selected from the group consisting of niobium 0.25 to 0.40 weight percent and zirconium 0.05 to 0.20 weight percent, at least one element selected from the group consisting of yttrium 0.05 to 0.20 weight percent, cerium 0.05 to 0.15 weight percent and lanthanum 0.05 to 0.15 weight percent, phosphorus not exceeding 0.025 weight percent, sulfur not exceeding 0.02 weight percent, copper not exceeding 0.20 weight percent, the remainder being substantially iron and unavoidable nonferrous impurities. The process for the manufacture of the steel comprises the steps of preparing a molten mass of said composition, pouring the molten mass into a mould and permitting it to solidify therein followed by cooling an ingot produced.