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303 HST

303 HST stainless steel bar is engineered to optimize machine performance in high volume, screw machines. It also delivers superior surface finish and product consistency. Traditional RAM 303 product is treated to enhance machinability when using carbide-tipped tooling at high cutting speeds. 303 HST, like RAM 303, is also alloy treated. However, the highly controlled production techniques for 303 HST produce a finished product with optimized mechanical properties. This provides optimum productivity and quality when using high-speed steel tooling at lower cutting speeds. As a result 303 HST is the most versatile premium machining product available. 303 HST is available in cold-drawn round bar and hex bar from 3/16" through 1" in diameter. It is chamfered and boxed. Round bar is centerless ground to 1/4 of standard tolerance.

303 HST should be heated to 1900°F minimum, and water quenched or rapidly cooled by other means. 303 HST cannot be hardened by heat treatment. 303 HST is not recommended for applications requiring welding. Its high sulfur content increases the likelihood of weld solidification cracking. When welding is necessary, AWS E312 filler metal may be considered. An alternative alloy for parts requiring welding is RAM 304L.

Common Trade Names

303 Stainless

Inventory

303 HST Round Bar, 303 HST Hex Bar

Specifications

UNS S30300, Werkstoff 1.4503, EN 1.4503, ASTM A 582, ASTM A 484, AMS 5640 Type 1

Chemical Composition, %

  Ni Cr Mn Si C S P Fe
MIN 8.0 17.0 - - - 0.15 - -
MAX 10.0 19.0 2.0 1.0 0.15 - 0.2 Balance

Features

  • Screw machine applications (multiple operations performed at same bar speed)
  • Excellent for carbide tooling and CNC machines
  • Controlled chemistry and surface finish for improved consistency
  • Produces good surface chipping and higher feeds and speeds compared to standard 303
  • Equally effective with high speed and carbide tooling
  • Good machinability leading to longer tool life

Applications

  • Major shafting
  • Conveyer Systems
  • Tight tolerance, straight shaft

Physical Properties

Density: 0.285 lb/inch3
Melting Point: 2525°F
Poisson's Ratio: 0.3
Electrical Resistivity: 481 Ohm-circ mil/ft

Temperature, °F 70 200
Coefficient* of Thermal Expansion, in/in°F x 10-6 - 9.4
Thermal Conductivity
Btu • ft/ft2 • hr • °F		 8.7 -
Modulus of Elasticity Dynamic, psi x 106 29.0 -

* 70°F to indicated temperature.

Machinability

High Speed Tooling

  Depthof Cut
/Width, in		 Cutting Speed, sfm Feed, ipr Tool Grade
Turning 0.04 90 - 180 0.006- 0.01 T15
0.015 90 -130 0.006 - 0.012 T15
Forming 0.20 110 -175 0.001- 0.0045 T15
0.40 100 - 140 0.0015- 0.004 T15
Cut-off 0.04- 0.15 up to 120 0.001- 0.005 T15
Drilling ALL 40 - 120 0.003 - 0.009 M35
Reaming ALL 40 - 120 0.003 - 0.0025 M35
Tapping ALL up to 120 N/A M35
Single Point Threading - - - -

Carbide Tooling

  Depth of Cut
/Width, in		 Cutting Speed, sfm Feed, ipr Tool Grade
Turning 0.04 150+ 0.0025- 0.012 P15 - M25
0.015 150+ 0.0025 - 0.012 P15 - M25
Forming 0.20 150+ 0.0025 - 0.012 P15 - M25
0.40 150+ 0.0025 - 0.012 P15 - M25
Cut-off 0.04- 0.15 120 - 360 0.002- 0.006 M25
Drilling ALL 80- 870 0.0025 - 0.012 P15 - M25
Reaming ALL 80- 870 0.0025- 0.012 P15 - M25
Tapping ALL - - -
Single Point Threading - 200 - 470 Thread Size: ¾" - 10"
Passes: 9-10		 M20

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Page Description: 303HST round bar inventory available for prompt shipment.
Keywords: 303 stainless, 303 stainless bar, 303 HST, UNS S30300, Werkstoff 1.4503, EN 1.4503, ASTM A 582, ASTM A 484, AMS 5640 Type 1