AISI 304 vs 304L Stainless Steel Properties (UNS S30403) Difference Between 304 and 304L (SS304L)

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AISI 304 VS 304L Stainless Steel (UNS S30403)

AISI 304 and 304L (SS304L) are austenitic stainless steels, and also known as 18/8 stainless steel. This article will introduce the differences between 304 and 304L stainless steel (304 vs 304L) from chemical composition, mechanical properties, corrosion resistance and weldability.

AISI 304L stainless steel is an ultra-low carbon version of SS 304 (Carbon content: ≤ 0.08 %). “L” is short for “Low carbon” and the maximum carbon content is 0.03%. The main purpose is to prevent carbide precipitation and improve weldability and corrosion resistance.

Difference Between 304 and 304L Chemical Composition

The table below gives 304L chemical composition, the maximum carbon content is 0.03%, while 304 is max 0.08%, other than that, the other composition are the same.

304L Chemical Composition, %
ASTM Type AISI (UNS) C, ≤ Si, ≤ Mn, ≤ P, ≤ S, ≤ Cr Ni N, ≤ Notes
ASTM A240/A240M 304L (UNS S30403) 0.03 0.75 2.00 0.045 0.030 17.5-19.5 8.0-12.0 0.10 Stainless Steel Plate,
Sheet, and Strip for Pressure Vessels
ASTM A276A/276M 0.03 1.00 2.00 0.045 0.030 18.0-20.0 8.0-12.0 Stainless Steel Bars and Shapes
ASTM A580/A580M 0.03 1.00 2.00 0.045 0.030 18.0-20.0 8.0-12.0 0.10 Stainless Steel Wire
ASTM A666 0.03 0.75 2.00 0.045 0.030 18.0-20.0 8.0-12.0 0.10 Annealed or Cold-Worked Austenitic Stainless Steel Sheet, Strip, Plate, and Flat Bar
ASTM A959 0.03 1.00 2.00 0.045 0.030 17.5-19.5 8.0-12.0 Wrought Stainless Steels
ASTM A473 0.03 1.00 2.00 0.045 0.030 18.0-20.0 8.0-12.0 Stainless Steel Forgings
ASTM A314 0.03 1.00 2.00 0.045 0.030 18.0-20.0 8.0-12.0 0.10 Billets and bars for forging

304 VS 304L Stainless Steel Properties

The following tables summarize 304 vs 304L stainless steel properties, including physical and mechanical properties.

Physical Properties

AISI 304L stainless steel physical properties are given in the following lists, including density, melting point and magnetic permeability.

SS304L Physical Properties
Density, g/cm3 (lb/in.3) 8.03 (0.29)
Melting point, °C (°F) 1400-1450 (2550-2650)
Magnetic permeability 1.02 (Approximate)

Mechanical Properties

304 vs 304L stainless steel mechanical properties at room temperature are listed in the following tables.

304 vs 304L Mechanical Properties
ASTM AISI Type Conditions Tensile Strength, MPa (ksi), ≥ 0.2% Yield Strength, MPa (ksi), ≥ Elongation in 50 mm (2 in.), %, ≥ Reduction of Area, %, ≥ Brinell Hardness (HBW), ≤ Rockwell Hardness (HRBW), ≤ Product forms
ASTM A276/A276M 304 Annealed, Hot finished 515 (75) 205 (30) 40 50 Bars and Shapes
304L 485 (70) 170 (25) 40 50
304 Annealed, Cold finished, Dia ≤ 12.7 mm (0.5 in.) 620 (90) 310 (45) 30 40
304L
304 Annealed, Cold finished, Dia > 12.7 mm (0.5 in.) 515 (75) 205 (30) 30 40
304L 485 (70) 170 (25) 30 40
ASTM A580/A580M 304 Annealed 520 (75) 210 (30) 35 50 Wire
304L 485 (70) 170 (25) 35 50
304 Cold finished 620 (90) 310 (45) 30 40
304L
ASTM A240/A240M 304 515 (75) 205 (30) 40 201 92 Plate, Sheet, and Strip
304L 485 (70) 170 (25) 40 201 92
ASTM A473/A473M 304 Annealed,  Sections ≤ 5 in. (127 mm) 515 (75) 205 (30) 40 50 Forgings
Annealed, Sections > 5 in. (127 mm) 70 (485)
304L 450 (65) 170 (25) 40 50

Heat Treatment

Recommended annealing temperatures for AISI 304L stainless steel is 1010-1120 °C (1850-2050 °F).

Hardening: SS304L cannot be hardened by heat treatment, but can be hardened by cold working.

Welding

Both 304 and 304L stainless steel can be easily welded with or without filler metal. If necessary, the recommended filler metal for SS304 is E308, and SS304L is E308L. Weldments that are too large or too complex for full annealing require stress relieving, 304 weldments are easily sensitized, and intergranular corrosion or stress-assisted intergranular corrosion occurs. It is strongly recommended to use stable stainless steel (type 321, 347 or 348) or low carbon type (SS304L or SS316L), especially for those that require long-time stress relief.

Corrosion Resistance

Due to its ultra-low carbon content, SS304L has better corrosion resistance than SS 304.

The following table list 304 vs 304L stainless steel corrosion rates in boiling 50% NaOH solution.

Material Base metal Weld
mm/yr mils/yr mm/yr mils/yr
SS304 (UNS S30400) 3.0 118 3.3 130
SS304L (UNS S30403) 1.8 71 2.2 87
SS316 (UNS S31600) 3.1 123.6 3.5 136.8
SS316L (UNS S31603) 1.97 77.6 2.17 85.4

Machinability (Machining)

The following tables show 304 and 304L stainless steel machinability (machining).

Nominal speeds and feeds for turning a variety of steels and cast irons with high-speed steel (HSS) single-point and box tools
Material Hardness, HB Condition Depth of cut, mm (in) High-speed steel tool Tool material
Speed Feed
m/min sfm mm/rev in./rev ISO AISI
Wrought austenitic: 201, 202, 301, 302, 304, 304L,
305, 308, 321, 347, 348, 384, 385
135-185 Annealed 1 (0.04) 34 110 0.18 0.007 S4, S5 M2, M3
4 (0.15) 27 90 0.4 0.015
8 (0.30) 21 70 0.5 0.02
16 (0.625) 17 55 0.75 0.03
Nominal speeds and feeds for turning a variety of steels and cast irons with carbide-tipped single-point and box tools
Material Hardness, HB Condition Carbide tool
Uncoated Coated
Speed Feed Tool material grade Speed Feed Tool material grade
Brazed Indexable
m/min sfm m/min sfm mm/rev in./rev ISO C m/min sfm mm/rev in./rev ISO C
Wrought austenitic: 201, 202, 301, 302, 304, 304L,
305, 308, 321, 347, 348, 384, 385
135-185 Annealed 105 350 120 400 0.18 0.007 K01, M10 C-3 160 525 0.18 0.007 CK01, CM10 CC-3
100 325 105 350 0.4 0.015 135 450 0.4 0.015
76 250 84 275 0.5 0.02 C-2 105 350 0.5 0.02 CC-2
60 200 64 210 0.75 0.03 K20, M20
Nominal speeds and feeds for turning a variety of steels and cast irons with ceramic tools
Material Hardness, HB Condition Depth of cut, mm (in) Speed Feed Type of ceramic
m/min sfm mm/rev in./rev
Austenitic: 201, 202, 301, 302, 304, 304L,
305, 308, 321, 347, 348, 384, 385
135-185 Annealed 1 (0.040) 425 1400 0.13 0.005 Cold-pressed alumina
4 (0.150) 275 900 0.25 0.010
8 (0.300) 185 600 0.40 0.015
Nominal speeds and feeds for turning a variety of steels and cast irons with high-speed steel and carbide cutoff and form tools
Material Hardness, HB Condition Speed Feed, mm/rev (in./rev) Tool material grade
Cutoff tool width Form tool width
m/min sfm 1.5 mm (0.062 in.) 3 mm (0.125 in.) 6 mm (0.250 in.) 12 mm (0.500 in.) 18 mm (0.750 in.) 25 mm (1.00 in.) 35 mm (1.50 in.) 50 mm (2.00 in.) ISO AISI or C
Austenitic: 201, 202, 301, 302, 304, 304L,
305, 308, 321, 347, 348, 384, 385
135-185 Annealed 26 85 0.033 (0.0013) 0.041 (0.0016) 0.050 (0.002) 0.050 (0.002) 0.041 (0.0016) 0.036 (0.0014) 0.030 (0.0012) 0.025 (0.001) S4, S5, K40, M40 M2, M3, C-2
84 275
Speeds and feeds for the deep-hole trepanning of various steels with high-speed tool steels and carbide tools
Material Hardness, HB Condition Speed Feed Tool material grade
m/min sfm mm/rev in./rev ISO AISI or C
Austenitic: 201, 202, 301, 302, 304, 304L,
305, 308, 321, 347, 348, 384, 385
135-185 Annealed 20 65 0.075 0.003 S4, S5 M2, M3
84 275 0.15 0.006 K20 C-2
225-275 Cold drawn 18 60 0.075 0.003 S4, S5 M2, M3
69 225 0.10 0.004 K20 C-2
Nominal speeds for the thread grinding
Material Hardness, HB Condition Thread designation Wheel identification ANSI Wheel speed Work speed
Pitch, mm Threads per 25 mm (1 in.) m/s sfm m/min sfm
Wrought austenitic stainless steels: 201, 202, 301, 302, 302B, 304, 304L,
305, 308, 309, 309S, 310, 310S, 314, 316, 316L,
317, 321, 330, 347, 348, 384, 385
135-275 Annealed or cold drawn 6-2.5 4-12 A90RB 43 8,500 1.2 4.0
2-1 13-27 A120SB 46 9000
0.8-0.45 28-63 A180TB 48 9500
0.4-0.35 64-80 A220UB 51 10000
Recommended speeds and feeds for the face milling of alloys with both high-speed steel and carbide cutters
Material Hardness, HB Condition Depth of cut, mm (in.) High-speed steel tool Carbide tool
Uncoated Coated
Speed Feed per tooth, mm (in.) Tool material grade, ISO (C) Speed, m/min (sfm) Feed per tooth, mm (in.) Tool material grade, ISO (C)
Speed, m/min (sfm) Feed per tooth, mm (in.) Tool material, ISO (AISI) Brazed, m/min (sfm) Indexable, m/min (sfm)
Wrought austenitic stainless steels: 201, 202, 301, 302, 304, 304L,
305, 308, 321, 347, 348, 384, 385
135-185 HB Annealed 1 (0.040) 40 (130) 0.20 (0.008) S4, S2 (M2, M7) 130 (430) 145 (475) 0.20 (0.008) K10, M20 (C-2) 215 (700) 0.20 (0.008) CK10, CM20 (CC-2)
4 (0.150) 30 (100) 0.30 (0.012) S4, S2 (M2, M7) 100 (325) 110 (360) 0.30 (0.012) K20, M30 (C-2) 145 (475) 0.30 (0.012) CK20, CM30 (CC-2)
8 (0.300) 24 (80) 0.40 (0.016) S4, S2 (M2, M7) 70 (230) 85 (280) 0.40 (0.016) K30, M40 (C-2) 105 (350) 0.40 (0.016) CK30, CM40 (CC-2)
Recommended speeds and feeds for the slab (or plain) milling of alloys with high-speed steel cutters
Material Hardness, HB Condition Depth of cut, mm (in.) Speed Feed per tooth High-speed steel tool material
m/min sfm mm (in.) ISO AISI
Wrought austenitic stainless steels: 201, 202, 301, 302, 304, 304L,
305, 308, 321, 347, 348, 384, 385
135-185 HB Annealed 1 (0.040) 55 180 0.15 (0.006) S4, S2 M2, M7
4 (0.150) 43 140 0.20 (0.008)
8 (0.300) 34 110 0.25 (0.010)
Recommended speeds and feeds for the end milling (peripheral) of alloys with both high-speed steel and carbide cutters
Material Hardness, HB Condition Radial depth of cut, mm (in.) High-speed steel tool Carbide tool
Speed, m/min (sfm) Feed, mm/tooth (in./tooth), at cutter diameter of: Tool material, ISO (AISI) Speed, m/min (sfm) Feed, mm/tooth (in./tooth), at cutter diameter of: Tool material, ISO (C)
10 mm (.375in) 12 mm (.5 in) 18 mm (.75 in) 25-50 mm (1-2 in.) 10 mm (.375in) 12 mm (.5 in) 18 mm (.75 in) 25-50 mm (1-2 in.)
201, 202, 301, 302, 304, 304L,
305, 308, 321, 347, 348, 384, 385
135-185 HB) Annealed 0.5 (0.020) 34 (110) 0.025 (0.001) 0.050 (0.002) 0.102 (0.004) 0.13 (0.005) S4, S5, S2 (M2, M3, M7) 110 (360) 0.013 (0.0005) 0.025 (0.001) 0.050 (0.002) 0.102 (0.004) K20, M20 (C-2)
1.5 (0.060) 24 (80) 0.050 (0.002) 0.075 (0.003) 0.13 (0.005) 0.15 (0.006) 82 (270) 0.025 (0.001) 0.050 (0.002) 0.075 (0.003) 0.13 (0.005)
diam/4
diam/4
21 (70) 0.025 (0.001) 0.050 (0.002) 0.102 (0.004) 0.13 (0.005) 72 (235) 0.025 (0.001) 0.038 (0.0015) 0.063 (0.0025) 0.102 (0.004)
diam/2
diam/2
18 (60) 0.025 (0.001) 0.038 (0.0015) 0.075 (0.003) 0.102 (0.004) 67 (220) 0.013 (0.0005) 0.025 (0.001) 0.050 (0.002) 0.075 (0.003)

Applications

SS 304L stainless steel applications: Food processing equipment, in particular beer brewing, milk processing and brewing equipment, weaving, welding screens, for mining, quarrying and water filtration, pressure vessels, storage tanks, heat exchangers, piping systems, flanges, accessories, valves and pumps, elbow, pipe tee, and reducing tee, etc.

AISI 304L Stainless Steel Equivalent

AISI 304L stainless steel equivalent to European EN (German DIN EN, British BSI EN, France NF EN), ISO, Japanese JIS and Chinese GB standard (for reference).

AISI 304L equivalent grade
US European Union ISO Japan China Australia India Rusia Korea
Standard Type Standard Grade (Steel Number) Standard Grade (ISO Number) Standard Grade Standard Grade Standard Grade Standard Grade Standard Grade Standard Grade
AISI SAE;
ASTM
304L
(UNS S30403)
EN 10088-1; EN 10088-2; EN 10088-3 X2CrNi18-9 (1.4307);
X2CrNi19-11 (1.4306)
ISO 15510 X2CrNi19-11 (4306-304-03-I) JIS G4303; JIS G4304; JIS G4305; SUS304L GB/T 20878;
GB/T 1220;
GB/T 3280
00Cr19Ni10;
022Cr19Ni10 (New name)

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1 Comment
  1. Rahul D says

    I have a solid cut piece(SS304 grade) of 61mm length with dia12 mm in which I want to drill a 6mm through hole. Can i drill it on a CNC machine? If yes, then by what kind of drill material( HSS, Carbide,etc)?
    The main point in this is that the drill hole should be accurate centered and it shouldnt go taper anywhere.

    Kindly suggest me on this and also let me know the best possible alternative too as the job will be in production quantity.

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