Essentially, fasteners are a kind of hardware device that joins two or more objects together mechanically. Produced in different alloy grades, one of the most common grades of fasteners is grade 304. Generally, Stainless Steel 304L Fasteners can be used to create a non-permanent joint. This means that these joints could be easily removed or they could be dismantled without causing any damage to the components being joined.

Stainless Steel 304L Fasteners

Stainless Steel 304L Fasteners

However, in some instances, a permanent joining would be required, especially in those applications where a temporary joint is not considered to be sufficient. This is why SS 304L stud bolts, are used. Apart from having good mechanical and weldability properties, this particular alloy has modified chemistry which serves the purpose by increasing its weldability. In the case of Stainless Steel 304L Nuts, the modification in its chemistry would be the lowering of carbon content and increasing the content of nitrogen in its alloy.


While a low carbon content plays a very important role in the weldability of the SS 304L threaded rod, this change can actually reduce the strength and mechanical properties of the alloy. Hence it would become a structurally weak alloy. In order to combat this issue, a substantial content of nitrogen is added to the alloy, thus restoring the mechanical properties almost to its previous state. Since Nitrogen stabilizes the austenite in UNS S30403 bolts and increases the hardenability of the alloy. Furthermore, the yield strength and resistance to pitting are also properties that are enhanced in the SS 304L hex bolt with the addition of nitrogen.

SS 304L hex bolt Torque chart

Sizes of Bolts (Inches)
Threads/ Inch
Standard Dry Torque (Inch-Pounds)
304L Stainless Steel
#2 56 2.5
64 3.0
#3 48 3.9
56 4.4
#4 40 5.2
48 6.6
#5 40 7.7
44 9.4
#6 32 9.6
40 12.1
#8 32 19.8
36 22.0
#10 24 22.8
32 31.7
Sizes of Bolts (Inches)
Threads/ Inch
Standard Dry Torque (Inch-Pounds)
304L SS
1/4 20 75.2
28 94.0
5/16 18 132
24 142
3/8 16 236
24 259
7/16 14 376
20 400
1/2 13 517
20 541

Stainless Steel 304L Fasteners Spec Chart

Standard ASTM A193/ ASME SA193
Lengths 3 upto 200 Millimetre
In Form of: Threading, Hex, Round, Square as per Gauge Etc.
Sizing 3/6 inch upto 2 inch | M3 – M56

Stainless Steel 304L nuts physical properties

Grades Density (kg per m3) Elastic Modulus (GPa) Thermal Expansion Mean Coefficient (m/ m/ °C) Thermal Conductivity (W/ m.K) Specific Heat 0-100°C (J/ kg.K) Electrical Resistivity

(n.m)

0-100°C 0-315°C 0-538°C at 100°C at 500°C
304L 8000 193 17.2 17.8 18.4 16.2 21.5 500 720

Chemical Structure of Alloy 304L washers

C Mn Si P S Cr Mo Ni N
0.030 max 2.0 max 0.75 max 0.045 0.030 18.0-20.0 8.0-12.0 0.10

SS 304L stud bolts Mechanical Behaviour

Tensile Strength (MPa) min Yield Strength 0.2% Proof (MPa) min Elongation (% in 50mm) min Hardness Rockwell B (HR B) max Hardness Brinell (HB) max
485 170 40 92 201

Material Equivalent of ASTM A193 grade 304L bolts

AISI Grade JIS Stainless Steel Notation EN/DIN Numerical UNS
designation
EN/DIN Symbolical
AISI 304L SUS304L SS 304L EN 1.4307 UNS S30403 X2CrNi18-9