A method for manufacturing a compressor scroll that appropriately impinges cavitation bubbles on target regions of a scroll. The method includes the step of water jet peening by jetting cavitation bubbles generated underwater by a water jet at a first side of an end plate (13A) of the scroll (13), with a center (P1, P2, P3) of the cavitation bubbles being offset from a center (O) of the spiral shape of a wall portion (13B) on the end plate (13A) and the step portion (13Aa) and the stepped portion (13Ba) positioned at an outer peripheral portion of the cavitation bubbles (C).

A plastically deformable almen strip is held under a predetermined underwater environment in which water jet peening is carried out, and a result of providing compressive residual stress in the water jet peening is confirmed by jetting water jet to the almen strip.

A stainless steel spring with excellent corrosion resistance and fatigue strength is provided by performing: a process of drawing a steel wire at a specific degree of drawing ε, the steel wire containing, in percentage by mass, C in an amount of 0.08% or lower, Si in an amount of 0.3% to 2.0%, Mn in an amount of 3.0% or lower, Ni in an amount of 8.0% to 10.5%, Cr in an amount of 16.0% to 22.0%, Mo in an amount of 0.5% to 3.0%, and N in an amount of 0.15% to 0.23%, with a remainder being made up of Fe and impurities; a process of obtaining a coiled steel wire; a process of heat treatment at from 500° C. to 600° C., and from 20 minutes to 40 minutes; a process of nitriding to form a nitride layer having a thickness of from 40 μm to 60 μm on a surface of the steel wire; a process of shot peening; and a process of heat treatment.

A stainless steel spring with excellent corrosion resistance and fatigue strength is provided by performing: a process of drawing a steel wire at a specific degree of drawing ε, the steel wire containing, in percentage by mass, C in an amount of 0.08% or lower, Si in an amount of 0.3% to 2.0%, Mn in an amount of 3.0% or lower, Ni in an amount of 8.0% to 10.5%, Cr in an amount of 16.0% to 22.0%, Mo in an amount of 0.5% to 3.0%, and N in an amount of 0.15% to 0.23%, with a remainder being made up of Fe and impurities; a process of obtaining a coiled steel wire; a process of heat treatment at from 500° C. to 600° C., and from 20 minutes to 40 minutes; a process of nitriding to form a nitride layer having a thickness of from 40 μm to 60 μm on a surface of the steel wire; a process of shot peening; and a process of heat treatment.

The seamless steel pipe according to the present disclosure includes a chemical composition consisting of, in mass %, C: 0.030% or less, Si: 1.00% or less, Mn: 1.00% or less, P: 0.030% or less, S: 0.0050% or less, Al: 0.001 to 0.100%, N: 0.0500% or less, O: 0.050% or less, Ni: 3.00 to 6.50%, Cr: more than 10.00 to 13.40%, Mo: 0.50 to 4.00%, V: 0.01 to 1.00%, Ti: 0.010 to 0.300%, and Co: 0.010 to 0.300%, with the balance being Fe and impurities, and satisfying Formula (1), and a microstructure containing, in volume ratio, 80.0% or more of martensite, wherein a depassivation pH of an inner surface is 3.50 or less.

Cr+2.0Mo+0.5Ni+0.5Co≥16.0  (1)

A method of treating bearing rolling elements or bearing rings after a hardening and temper heat treatment is disclosed. The method may include treating the bearing rolling elements in a tumbling treatment and then in a duplex hardening treatment. The method may include treating the bearing rings in a peening treatment and then in a duplex hardening treatment. The duplex hardening treatment may also include at least one sequential process segment consisting of subjecting the bearing rolling element & rings to a nitriding process to increase the surface hardness and compressive residual stress. The combined two-step process produces a deep surface/sub-surface residual stress greater than the depth of the maximum operating von-Mises shear stress along with an ultra-hard surface with high magnitude of compressive residual stress. In so doing, the bearing ring and rolling elements will have significantly enhanced rolling contact fatigue resistance and resistance to surface imperfections and debris.

A method of treating bearing rolling elements or bearing rings after a hardening and temper heat treatment is disclosed. The method may include treating the bearing rolling elements in a tumbling treatment and then in a duplex hardening treatment. The method may include treating the bearing rings in a peening treatment and then in a duplex hardening treatment. The duplex hardening treatment may also include at least one sequential process segment consisting of subjecting the bearing rolling element & rings to a nitriding process to increase the surface hardness and compressive residual stress. The combined two-step process produces a deep surface/sub-surface residual stress greater than the depth of the maximum operating von-Mises shear stress along with an ultra-hard surface with high magnitude of compressive residual stress. In so doing, the bearing ring and rolling elements will have significantly enhanced rolling contact fatigue resistance and resistance to surface imperfections and debris.

A processing method of NPR steel rebar rod is disclosed. The NPR steel rebar is cold processed and has a yield strength of 800˜950 MPa, a tensile strength of 900˜1100 MPa, and a percentage elongation at maximum force of not less than 10˜40%. The processing method comprises the following steps: a I-shaped placing step L20, an uncoiling step L30, a flattening step L40, a butt welding step L50, a sandblasting step L60, a straightening step L70, a pointing step L80, a hydraulic head-pushing step L90, a cold drawn spiral ribbing step L10, a straight forward continuous wire drawing and traction step L11, a pre-straightening step L12, a fine straightening step L13, and a cutting-off step L14. The processing method can meet the automatic intelligent production requirements of NPR steel rebar, cold rolled spiral NPR steel rebar, and pre-stressed NPR steel rebar.

In an embodiment a method includes providing a workpiece, attaching a marking to the workpiece such that the marking is integrally bonded to the workpiece, wherein attaching the marking includes applying at least one raw material for the marking, heating the workpiece with the at least one raw material such that the marking is formed from the at least one raw material and performing a surface treatment of the workpiece at least in an area with the marking, wherein performing the surface treatment includes shot peening, sand blasting or material-removing etching against which the marking is resistant to, wherein the marking remains readable on the workpiece at least until after performing the surface treatment, and wherein the marking has, in at least a part of a near ultraviolet, a visible and/or a near-infrared spectral range relative to the workpiece, at least one of a degree of reflection difference, a reflectance difference or an albedo difference of at least 10 percentage points.

In an embodiment a method includes providing a workpiece, attaching a marking to the workpiece such that the marking is integrally bonded to the workpiece, wherein attaching the marking includes applying at least one raw material for the marking, heating the workpiece with the at least one raw material such that the marking is formed from the at least one raw material and performing a surface treatment of the workpiece at least in an area with the marking, wherein performing the surface treatment includes shot peening, sand blasting or material-removing etching against which the marking is resistant to, wherein the marking remains readable on the workpiece at least until after performing the surface treatment, and wherein the marking has, in at least a part of a near ultraviolet, a visible and/or a near-infrared spectral range relative to the workpiece, at least one of a degree of reflection difference, a reflectance difference or an albedo difference of at least 10 percentage points.