Abstract: A spring steel contains, in terms of mass %, C: 0.35% or more and 0.55% or less, Si: 1.60% or more and 3.00% or less, Mn: 0.20% or more and 1.00% or less, Cr: 0.10% or more and 1.50% or less, Ni: 0.05% or more and 0.30% or less, and Cu: 0.05% or more and 1.00% or less, and substantially does not contain V, the remainder being Fe and unavoidable impurities.

Abstract: A spring has a Rockwell hardness of HRC 53 to HRC 56 and a dislocation density ? (cm?2) that satisfies the formula ??1.4×1011×H?6.7×1012 in the Rockwell hardness range of HRC 53 to HRC 56, in which H is the Rockwell hardness. The spring also has a prior austenite grain size number of 10 or higher.

Abstract: A manufacturing method of a coil spring for an automobile suspension includes forming a material into a coil shape; performing a heat treatment step on the material; performing a warm shot peening step on the material, and performing a hot setting step on the material. By performing the warm shot peening step prior to the hot setting step, a stronger compressive residual stress is imparted in a direction along which a large tensile stress acts during actual use of the coil spring, thereby improving sag resistance and durability of the coil spring. A coil spring is also manufactured according to this method.

Abstract: A high-strength spring steel and a spring are provided that have superior corrosion fatigue strength. The spring steel comprises, in mass percent, 0.35-0.55% C, 1.60-3.00% Si, 0.20-1.50% Mn, 0.10-1.50% Cr, and at least one of 0.40-3.00% Ni, 0.05-0.50% Mo and 0.05-0.50% V, the balance being substantially Fe and incidental elements and impurities.

Abstract: A spring has a Rockwell hardness of HRC 53 to HRC 56 and a dislocation density ? (cm?2) that satisfies the formula ??1.4×1011×H?6.7×1012 in the Rockwell hardness range of HRC 53 to HRC 56, in which H is the Rockwell hardness. The spring also has a prior austenite grain size number of 10 or higher.

Abstract: A spring steel and spring having superior corrosion fatigue strength and a strength on the order of HRC 53 to HRC 56 are disclosed. The spring steel comprises a tempered martensite and 2.1 to 2.4% Si in terms of percent by mass of the total mass of the spring steel.

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: The present application provides a high strength spring steel and a high strength spring that have superior corrosion fatigue strength. The spring steel comprises, in terms of percent by mass, 0.35-0.55% C, 1.60-3.00% Si, 0.20-1.50% Mn, 0.10-1.50% Cr and at least one element selected from 0.40-3.00% Ni, 0.05-0.50% Mo 0.05-0.50% V, the balance being at least substantially Fe and incidental elements and impurities.

Abstract: The present application provides a high strength spring steel and a high strength spring that have superior corrosion fatigue strength. The spring steel comprises, in terms of percent by mass, 0.35-0.55% C, 1.60-3.00% Si, 0.20-1.50% Mn, 0.10-1.50% Cr and at least one element selected from 0.40-3.00% Ni, 0.05-0.50% Mo 0.05-0.50% V, the balance being at least substantially Fe and incidental elements and impurities.

Abstract: A manufacturing method of a coil spring for an automobile suspension includes forming a material into a coil shape; performing a heat treatment step on the material; performing a warm shot peening step on the material, and performing a hot setting step on the material. By performing the warm shot peening step prior to the hot setting step, a stronger compressive residual stress is imparted in a direction along which a large tensile stress acts during actual use of the coil spring, thereby improving sag resistance and durability of the coil spring. A coil spring is also manufactured according to this method.

Abstract: A spring steel and spring having superior corrosion fatigue strength and a strength on the order of HRC 53 to HRC 56 are disclosed. The spring steel comprises a tempered martensite and 2.1 to 2.4% Si in terms of percent by mass of the total mass of the spring steel.

Abstract: A high-strength spring steel and a spring are provided that have superior corrosion fatigue strength. The spring steel comprises, in mass percent, 0.35-0.55% C, 1.60-3.00% Si, 0.20-1.50% Mn, 0.10-1.50% Cr, and at least one of 0.40-3.00% Ni, 0.05-0.50% Mo and 0.05-0.50% V, the balance being substantially Fe and incidental elements and impurities.