A stabilizer formed by using a metal bar having a solid structure and configured to reduce a displacement between right and left wheels, including a torsion part extending in a vehicle width direction, being capable of a torsional deformation, and having a diameter of 10 to 32 mm, is provided. The stabilizer has a chemical composition containing at least C: 0.15% by mass or more to 0.39% by mass or less, Mn, B, and Fe, and also has a metal structure 90% or more of which is a martensite structure.

The invention provides a production method for stabilizers which produces with high productivity in a compact production line, without tempering. The production method for stabilizers of the invention includes: forming a steel bar material containing at least C: 0.15 wt % to 0.39 wt %, Mn, B and Fe into a product shape by bending; and quenching the bent steel bar material in a medium having a heat transfer coefficient higher than or close to that of water.

A canted coil spring includes a core wire 10 formed of steel having a pearlite structure; and a copper plating layer 20 formed of copper or a copper alloy and covering an outer circumferential surface 11 of the core wire 10. The steel contains 0.5 mass % or more and 1.0 mass % or less carbon, 0.1 mass % or more and 2.5 mass % or less silicon, and 0.3 mass % or more and 0.9 mass % or less manganese, with the balance being iron and inevitable impurities. The copper plating layer 20 has a crystallite size of 220±50 Å.

A canted coil spring includes a core wire 10 formed of steel having a pearlite structure; and a copper plating layer 20 formed of copper or a copper alloy and covering an outer circumferential surface 11 of the core wire 10. The steel contains 0.5 mass % or more and 1.0 mass % or less carbon, 0.1 mass % or more and 2.5 mass % or less silicon, and 0.3 mass % or more and 0.9 mass % or less manganese, with the balance being iron and inevitable impurities. The copper plating layer 20 has a crystallite size of 220±50 Å.

The invention relates to a cold roiled and hardened martensitic/austenitic stainless steel strip for flapper valves in the compressors, wherein the steel strip is made from steel combining, in weight % (wt. %), the following elements: C 0.3-0.5, Si 0.2-0.8, Mn 0.2-1.0, Cr 12.0-15.0, Mo 0.50-2.00, N 0.02-0.15, and V 0.01-0.20. The steel has a matrix consisting of tempered martensite and between 5 and 15 volume % austenite and a tensile strength (R.sub.m) of 1970-2300 MPa.

The invention relates to a cold roiled and hardened martensitic/austenitic stainless steel strip for flapper valves in the compressors, wherein the steel strip is made from steel combining, in weight % (wt. %), the following elements: C 0.3-0.5, Si 0.2-0.8, Mn 0.2-1.0, Cr 12.0-15.0, Mo 0.50-2.00, N 0.02-0.15, and V 0.01-0.20. The steel has a matrix consisting of tempered martensite and between 5 and 15 volume % austenite and a tensile strength (R.sub.m) of 1970-2300 MPa.

A leaf spring device includes a main leaf made of a steel plate including an elastic section configured to generate elastic force when bent; and an eye section formed in an end portion of the elastic section, the elastic section and the eye section being tempered. There is also provided a method for manufacturing the leaf spring device. The eye section is formed by rolling the end of the elastic section into a circular form. The eye section is tempered at a higher temperature than the elastic section.

A leaf spring device includes a main leaf made of a steel plate including an elastic section configured to generate elastic force when bent; and an eye section formed in an end portion of the elastic section, the elastic section and the eye section being tempered. There is also provided a method for manufacturing the leaf spring device. The eye section is formed by rolling the end of the elastic section into a circular form. The eye section is tempered at a higher temperature than the elastic section.

A method for manufacturing steel, by quenching and tempering a seamless pipe for use as a material of a hollow spring, where the seamless pipe including predetermined components is subjected to a heat treatment which is performed to satisfy quenching conditions (1) and tempering conditions (2),

(1) quenching conditions:

26,000≦(T1+273)×(log(t1)+20)≦29,000  formula (1) 900° C.≦T1≦1,050° C., 10 seconds≦t1≦1,800 seconds, where T1 is a quenching temperature (° C.), and t1 is a holding time (seconds) in a temperature range of 900° C. or higher, and

(2) tempering conditions:

13,000≦(T2+273)×(log(t2)+20)≦15,500  formula (2) T2≦550° C., and t2≦3,600 seconds, where T2 is a tempering temperature (° C.), and t2 is a total time (seconds) from start of heating to completion of cooling.

The present disclosure provides a bow-spring centralizer by using thinner bows of advanced alloys and thermal conditioning that can reduce the thickness of the bows compared to traditional bows, and yet provide sufficient restoring force after compression in a tight annulus with little radial thickness. The present disclosure also provides a specially shaped centralizer bow with cross sections that can reduce running force, increase stiffness and strength, and/or still maintain a sufficient restoring force.