440C • 430 • 420 • 316 • 304/302/18-8 
Stainless Steel Balls: AISI-440C
Martensitic Steel Profile
Stainless steel balls of this straight chromium steel provide maximum
hardness, toughness and dimensional stability. They are highly resistant
to rolling-contact fatigue. 440C stainless steel balls are always used
in a hardened condition, perform similarly to tool steels, and are ideal
for use in antifriction bearings (rolling bearings). After quenching, the balls
are immediately subjected to ultra-low temperatures to stabilize their
structure and further enhance hardness.
Characteristics
440C stainless steel balls achieve the highest hardness following heat
treatment: 60 HRC. The material is ferro-magnetic and makes a good
permanent magnet. Hartford 440C stainless steel balls are passivated to
remove free iron contaminants and facilitate spontaneous formation of
a protective passive film.
Corrosion Resistance
440C stainless steel balls have excellent resistance to steam, crude oil,
gasoline, blood, perspiration, alcohol, sterilizing solutions, fresh water,
and foodstuffs.
Note: Hartford also provides stainless steel ball manufacturing using
TrimRite®, which offers better corrosion resistance.
Hardness
Rockwell C 58-62 measured on parallel flats.
Sizes
1/32" to 2 1/2" in grades 10 through 1000.
TrimRite is a registered trademark of CRS Holdings, Inc., a subsidiary of Carpenter Technology Corp.
........................................................................................................................ Stainless Steel Balls: AISI 430
Ferritic Steel
Profile
Economical alternative to 302/304 for corrosive environments and conditions.
Magnetic properties offer advantages in assembly of 430 products. Characteristics
Offers good resistance to mild atmospheric conditions. Provides superior
resistance to chloride stress corrosion at elevated temperatures compared
to 302/304 or 316 materials. All balls of this alloy are passivated. Corrosion Resistance
430 stainless steel balls are resistant to steam, dairy products, nitric acid
and many petroleum products and organic materials. Superior material for
use in cosmetic applications. Hardness
Annealed B - 75 - 95 measured on parallel flats. Sizes
3/32" to 1" in grades 100 through 2000.
Cosmetic grade balls are readily available. ........................................................................................................................ Stainless Steel Balls – AISI 420
Martensitic Steel Profile
420 stainless steel balls demonstrate good wear characteristics and
hardness. Slightly less hardness, and greater corrosion resistance, compared
to 440C. Corrosion Resistance
Excellent corrosion resistance from mild atmospheres, fresh water, steam,
blood, ammonia, petroleum products, and mild acidic environments. Hardness
Rockwell C 48-52
Sizes
3/64" to 2 1/2" in grades 10 through 1000
........................................................................................................................ Stainless Steel Balls – AISI 316
Profile
316 stainless steel balls have exceptional corrosion resistance, thanks to
their higher nickel and molybdenum content. Developed to resist attack
by sulphuric, phosphoric and acetic acid compounds; used extensively
in applications involving photographic chemicals, inks, rayon, rubber, textile
bleaches, dye stuffs and high temperature equipment.
FDA approved for medical grade material.
Characteristics
These balls made from type 316 have higher tensile and creep strength at
elevated temperatures than conventional 316 alloys. This material is
passivated to reduce reactivity.
Physical Constants
Density - 0.29 lbs./cu. in. Sizes
Available in sizes from 3/64” to 2 ½” in grades 50 through 1000.
........................................................................................................................ Stainless Steel Balls - AISI 304/302 (18-8)
Austenitic Stainless Steels Profile
Type 18-8 stainless steel balls are used when conditions require corrosion
performance and toughness not available in hardenable stainless steels.
Principal applications are in couplings, valves and pumps.
Characteristics
Low magnetic permeability: annealed, 1.003; cold worked, 1.10;
severely cold worked, 10.0. High tensile strength at elevated temperatures.
18-8 stainless steel work-hardens rapidly. Stainless steel balls of this
material are passivated.
Corrosion Resistance
Type 18-8 stainless steel balls resist attack by oxidizing solutions, foodstuffs,
sterilizing solution and most organic chemicals. They are susceptible to attack
by halogen acids and moderately resistant to the sulphur acids.
Hardness
Annealed Rockwell B 75-95.
Not annealed; Rockwell C 39.
Sizes
3/64 to 2 1/2" in grades 50 through 1000.
For more on stainless steel balls, see our "Facts" page.
........................................................................................................................
Precision stainless steel balls are a Hartford specialty, but if you're
looking for a cost-effective alternative, here's something to consider: Precision Glass Balls an Excellent
Alternative to Stainless Steel Balls
Precision Glass Balls provide a practical and affordable alternative for
applications where corrosion resistance is critical. Precision Glass Balls are
particularly effective in applications where corrosion resistance is a primary
requirement and where extreme thermal changes are not a factor. Like 300-series stainless, glass is highly resistant to corrosion and chemical
absorption, and it is non-magnetic. Glass balls are ideal for valve applications
in medical devices, instrumentation gauges, pumps, water treatment bearings,
roll-on applicators, and many other uses.
Most 300-series stainless steel balls contain between 8 and 14 percent
nickel, a material whose availability and cost have been volatile. In contrast,
the cost of glass has remained stable, because its primary element is “silica,”
or sand, which remains in abundant supply. Hartford Technologies manufactures glass balls from soda-lime and
borosilicate materials. Soda-lime balls are recommended for applications
requiring hardness and excellent resistance to corrosion. In applications
where high temperatures and sudden temperature changes are also
expected, borosilicate glass is recommended for its additional resistance
to chemical corrosion and temperature fluctuation. Glass Balls can be supplied to the same diameter and “sphericity” tolerances
as stainless steel balls, in smooth, matte, and polished finishes, in plain or
other color, and in sizes ranging from 1/32” (0.8mm) through 1-1/4” (31.75mm).
Balls can also be manufactured to meet a 100,000/10,000 cleanroom standard.
Hartford’s advanced high-speed visual inspection system evaluates the
diameter, roundness, and purity of each ball. Whether your requirement is for balls manufactured from carbon steel,
stainless steel, tungsten carbide, brass, glass, or plastics, Hartford
Technologies offers benefits you can bank on: a unique 2-continent
logistics strategy that shortens delivery times to multiple destinations, the
industry’s strongest technical team – and greatest overall value. |
