Stainless steel

Stainless Steel - Grade 303

Chemical Formula

Fe, <0.15% C, 17-19% Cr, 8-10% Ni, <2% Mn, <1% Si, <0.2% P, >0.15%S

Background

Grade 303 represents the optimum in machinability among the austenitic stainless steels. It is primarily used when production involves extensive machining in automatic screw machines. Machinability Rating (compared to B1212) is approximately 78%.
303 is also available as a "Ugima" Improved Machinability grade, with machinability even higher than that of the standard 303.
The sulphur addition which is responsible for the improved machining and galling characteristics of Grade 303 lowers its corrosion resistance to below that of Grade 304. As for other austenitic grades the structure gives 303 excellent toughness, although the sulphur in 303 reduces its toughness slightly.

Grade 303Se (UNS S30323) has a selenium rather than sulphur addition, improving the hot and cold forming characteristics over those of 303 and providing a smoother machined surface finish. The machinability rate is also slightly reduced. Grade 303Se is not readily available in Australia.

Key Properties

These properties are specified for long product (bar) in ASTM A582. Similar but not necessarily identical properties are specified for other products such as wire and forgings in their respective specifications. Grade 303 is not produced in flat rolled products.
Composition

Typical compositional ranges for grade 303 stainless steels are given in table 1.

Table 1. Composition ranges for 303 grade stainless steel

Grade

C

Mn

Si

P

S

Cr

Mo

Ni

Se

303

min.

max.

-

0.15

-

2.00

-

1.00

-

0.20

0.15

-

17.0

19.0

-

8.0

10.0

-

303Se

min.

max.

-

0.15

-

2.00

-

1.00

-

0.20

0.06

-

17.0

19.0

-

8.0

10.0

0.15

min

Mechanical Properties

Typical mechanical properties for grade 303 stainless steels are given in table 2.

Table 2. Mechanical properties of 303 grade stainless steel

Grade

Tensile Strength (MPa)

Yield Strength 0.2% Proof (MPa)

Elongation (% in 50mm)

Hardness

Rockwell B (HR B)

Brinell (HB)

303

-

-

-

-

262 max

Physical Properties

Typical physical properties for annealed grade 303 stainless steels are given in table 3.

Table 3. Physical properties of 303 grade stainless steel in the annealed condition

Grade

Density (kg/m3)

Elastic Modulus (GPa)

Mean Coefficient of Thermal Expansion (mm/m/°C)

Thermal Conductivity (W/m.K)

Specific Heat 0-100°C (J/kg.K)

Electrical Resistivity (nW.m)

0-100°C

0-315°C

0-538°C

at 100°C

at 500°C

303

8027

193

17.3

17.8

18.4

16.3

21.5

500

720

Grade Specification Comparison

Approximate grade comparisons for 303 stainless steels are given in table 4.

Table 4. Grade specifications for 303 grade stainless steel

Grade

UNS No

Old British

Euronorm

Swedish SS

Japanese JIS

BS

En

No

Name

303

S30300

303S31

58M

1.4305

X8CrNiS18-9

2346

SUS 303

303Se

S30323

303S42

-

-

-

-

SUS 303Se

These comparisons are approximate only. The list is intended as a comparison of functionally similar materials not as a schedule of contractual equivalents. If exact equivalents are needed original specifications must be consulted.

Possible Alternative Grades

Possible alternative grades to grade 303 stainless steels are given in table 5.

Table 5. Possible alternative grades to 303 grade stainless steel

HomeCompany ProfileProductsFacilitiesContact UsMaterial ReferenceQuality AssuranceShippingCustom
粤ICP备08008535号 ©2011 SUNCLES INDUSTRY LIMITED ALL RIGHTS RESERVED