I. Basic Material

Item	Technical Parameters
Material Grade	440C
Chinese National Standard Grade	95Cr18
UNS Grade	S44004
DIN Grade	1.4125

II. Chemical Composition (Mass Fraction wt%)

C	Si	Mn	P	S	Cr
0.95～1.20	≤1.00	≤1.00	≤0.040	≤0.030	16.00～18.00

III. Mechanical Properties (Quenched and Tempered)

Item	Mechanical Properties
Elongation after Fracture A	≥5%
Brinell Hardness	255～350 HB

IV. Dimensional Accuracy Specifications

Item	Technical Requirements
Common Diameter Range	φ3.0mm ～ φ300mm
Diameter Tolerance	Standard: h8, h9; High Precision: h7, f7, g6, h6
Roundness	≤1/2 of diameter tolerance
Straightness	≤0.10mm/1000mm
Standard Length	φ40mm and below: 3 meters; Above φ40mm: 6 meters available (custom fixed lengths supported)
End Face Requirements	Flat ends, chamfered and deburred

V. Processing Technology & Surface Roughness

Process Type	Complete Process Flow	Surface Roughness
Process 1	Hot-rolled base material → Precision drawing → Centerless precision grinding	Ra 0.4～0.8μm
Process 2	Hot-rolled base material → Peeling and straightening → Centerless precision grinding	Ra 0.4～0.8μm
Process 3	Hot-rolled base material → Peeling and straightening → Centerless precision grinding → Polishing	Ra ≤0.2μm
Process 4	Hot-rolled base material → Peeling and straightening → Surface quenching → Centerless precision grinding → Polishing	Ra ≤0.2μm

VI. Physical Properties and Surface Quality

Item	Parameter Description
Material Density	7.78 g/cm³
Magnetism	Magnetic
Appearance Quality	Free of cracks, peeling, pinholes, scale, rust and collision damages

VII. Application Scenarios
Bearings, valve seats, cutting tools, measuring tools, pump shafts, high-hardness wear-resistant precision shafts, corrosion-resistant high-hardness structural components.