Abstract: A spring steel having a good sag-resistance and a good hardenability comprises by weight 0.5-0.8% carbon, 1.5-2.5% silicon, 1.6-2.5% manganese and a member or members selected from a group consisting of 0.05-0.5% vanadium, 0.05-0.5 niobium and 0.05-0.5% mobybdenum, the remainder being iron together with impurities. The steel may further contain a member or members selected from a group consisting 0.0005-0.01% boron, 0.2-1.0% chromium, 0.2-2.0% nickel and not greater than 0.3% rare-earth elements and/or a member or members selected from a group consisting of 0.03-0.1% aluminum, 0.02-0.1% titanium and 0.02-0.1% zirconium.

Abstract: A leaf spring construction including at least one leaf element made from a flat sheet of uniform width and thickness, the leaf element having an arcuate shape in the transverse cross-section with a convex surface on tension stress side and a concave surface on compression stress side thereof, the leaf element having in cross-section a width b and a transverse center line forming an arc of a radius r.sub.c with the relation of2.0.gtoreq.r.sub.c /b.gtoreq.0.64and a thickness t with the relation of0.2.gtoreq.t/b.gtoreq.0.05In a laminated leaf spring including a plurality of such leaf elements, each leaf element is formed to have a convex surface of a radius of curvature r.sub.o and a concave surface of a radius of curvature r.sub.i in the relation of1.2.gtoreq.r.sub.o /r.sub.i .gtoreq.1.0.

Abstract: A steel for use in a vehicle suspension spring having a good sag-resistance comprising by weight 0.50-0.80% carbon, 1.50-2.50% silicon, 0.50-1.50% manganese, a member or members selected from a group consisting of 0.05-0.50% vanadium, 0.05-0.50% niobium and 0.05-0.50% molybdenum, the remainder being iron together with impurities. The steel may further contain a member or members selected from a group consisting of 0.0001-0.01% boron and 0.20-1.00% chromium, and not greater than 0.0008% nitrogen.

Abstract: Method for manufacturing long bars, round, square or flat, employing multi-tandem type roller dies mechanism in which each roller gap is controlled by the roller gap adjusting mechanism, and apparatus preferably applicable that method. The apparatus is provided with a plurality sets of roller dies, controllers for outputting a respective target roller gap for each roller dies, roller adjusting mechanisms capable of shifting, in accordance with the commanding signals from servo devices based on the output target roller gap, each roller of each set of roller dies symmetrically about the axial line of the die hole formed by the roller dies, roller position sensors for measuring the respective roller gap in order to feed back the measured results to the servo devices, and a propelling mechanism for imparting a deformable blank propelling force.

Abstract: A method for breaking a steel rod into billets for forging, rolling, etc., by cutting a circumferential notch in the surface of the steel rod, locally heating the surface areas of the rod adjacent the notch so that the temperature at the notch bottom is less than a transformation temperature of the steel of the rod, quenching the rod thereby to develop a crack extending from the notch bottom toward the center of the rod, and applying a mechanical load to break the rod along its notched portion.