Abstract: A steel material for a solid stabilizer which has high bendability, high hardenability, and high quenching crack resistance, a solid stabilizer having high strength, and a manufacturing method of the solid stabilizer. The steel material for the solid stabilizer contains, in mass %, 0.24 to 0.40% of C, 0.15 to 0.40% of Si, 0.50 to 1.20% of Mn, 0.03% or less of P, 0.30% or less of Cr, 0.01 to 0.03% of Ti, and 0.0010 to 0.0030% of B. The steel material for the solid stabilizer satisfies a condition of formula (1) below. Hardness in a radial center portion of the steel material for the solid stabilizer after tempering is 400 HV or more, and a martensite ratio in the radial center portion after the tempering is 80% or more. 1.24<(2C+0.1Si+0.4Mn+0.4Cr)×{1+(1.5B?300B2)×240}<1.

Abstract: A bearing device for internal combustion engines, comprising a crankshaft of an internal combustion engine and bearings supporting the crankshaft, and wherein the crankshaft is made of steel having not been subjected to surface hardening and having a structure, which is mainly composed of pearlite having the pro-eutectoid ferrite fraction of at most 3%, and is processed to have the surface roughness Rz of at most 0.8 ?m, and wherein the bearings have an aluminum bearing alloy bonded to a back plate thereof and contain, as an alloy component thereof, at least Si particles of less than 4 mass %, whereby early abrasion and scratches of the crankshaft are suppressed to be equivalent to or less than abrasion loss and scratches of conventional DCI shafts.

Abstract: A bearing device for internal combustion engines, comprising a crankshaft of an internal combustion engine and bearings supporting the crankshaft, and wherein the crankshaft is made of steel having not been subjected to surface hardening and having a structure, which is mainly composed of pearlite having the pro-eutectoid ferrite fraction of at most 3%, and is processed to have the surface roughness Rz of at most 0.8 &mgr;m, and wherein the bearings have an aluminum bearing alloy bonded to a back plate thereof and contain, as an alloy component thereof, at least Si particles of less than 4 mass %, whereby early abrasion and scratches of the crankshaft are suppressed to be equivalent to or less than abrasion loss and scratches of conventional DCI shafts.

Abstract: A non-heat-treating steel for hot forging which does not require heat treatment and still yields high static strength, toughness and fatigue resistance only by air cooling after hot forging. The main ingredients are, by weight %, 0.10-0.30% C, 0.05-0.50% Si, 0.80-2.00% Mn, 0.30-1.50% Cr, 0.05-0.50% Mo, 0.002-0.060% Al, 0.05-0.50% V, 0.008-0,020% N, and the balance Fe and inevitable impurities, where contents of some component elements should satisfy the following conditions,%Mo+%V.gtoreq.0.20(%),1.8.times.%Mn+%Cr+0.5.times.%Mo.ltoreq.20.times.%C, andBs.gtoreq.550(.degree.C.)where Bs represents the bainite transformation temperature and is defined by Bs=830-270.times.C%-90.times.Mn%-70.times.Cr%-83.times.Mo%. Since the mechanical properties are obtained through air cooling, the mechanical properties are stable albeit the size of the forged article and the forging conditions. The non-heat-treating steel is especially suited for use in chassis parts of automobiles and hydraulic parts of construction machines.