Abstract: An extra-low carbon cold rolled steel sheet useful for use in automobiles and the like, having an improved spot weldability is obtained by combining and adding Ti, Nb and B in predetermined amounts to an extra-low carbon steel to control the amount of fine Ti precipitate dispersed in steel to within a specified reasonable range. Furthermore, the spot weldability is improved by controlling the production conditions of the extra-low carbon steel sheet to within specified reasonable ranges.

Abstract: A resin composition for a composite-type vibration-damping material which comprises a saturated copolyester having a weight average molecular weight of at least 10,000 and a softening point of 50.degree. to 150.degree. C. and a polyfunctional isocyanate compound as a cross-linking agent and which, when cross-linked, has a degree of gelation (degree of cross-linking) of at least 10% and a composite-type vibration-damping material produced by use of the resin composition, have excellent adhesive strength and formability.When the resin composition is admixed with a conductive substance, a vibration-damping material produced by use of the admixture has excellent spot-weldability in addition to the above-mentioned excellent properties.

Abstract: An extra-low carbon cold rolled steel sheet useful for use in automobiles, and the like, having an improved spot weldability is obtained by combining and adding Ti, Nb and B in predetermined amounts to the extra-low carbon steel to control the amount of fine Ti precipitate dispersed in steel to within a specified reasonable range. Furthermore, the spot weldability is improved by controlling the production conditions of the extra-low carbon steel sheet to within specified reasonable ranges.

Abstract: Disclosed is a vibration damping composite laminate of the type comprising a viscoelastic polymer composition layer interposed between two layers of metal, which is high in the damping effectiveness and can readily be spot-welded to metal structures. Essentially the polymer composition is a blend of a polyvinyl acetal resin and particulate carbon which amounts to 10-80 wt % of the composition, on condition that the ratio of the mean particle size of the particulate carbon to the thickness of the polymer composition layer is from 0.5 to 1.7. Optionally the polymer composition may further comprise a polyolefine resin and/or a plasticizer.

Abstract: A lightweight composite material consisting of two metal sheets and an intermediate layer consisting of a mixture of resin and graphite and held between the metal sheets. The intermediate layer has a specifically limited thickness and a specifically limited graphite content, and the graphite has a specifically limited particle size distribution. The composite material is excellent in the spot weldability, bending rigidity, vibration-damping property and heat insulating property, and can be expected to be widely used as a material for automobile and further materials for industrial machine and architecture.