Stainless Steel Grades Chart

Q: What is the difference between 303 and 304 stainless steel?

303 has added sulfur that makes it much easier to machine. It rates 78% on the machinability scale. 304 is harder to cut at 45%. But 304 has better corrosion resistance. Pick 303 when you need fast machining and tight tolerances. Pick 304 when the part must resist rust in harsh conditions.

Q: What is 17-4 PH stainless steel?

17-4 PH is a precipitation hardening stainless steel. It can be heat treated to very high strength levels. In the H900 condition, it reaches 190 ksi tensile strength. It also resists corrosion well. It is used in aerospace, defense, and medical parts that need both strength and rust resistance.

Grade ▲	Type ▲	Tensile (ksi) ▲	Yield (ksi) ▲	Hardness ▲	Machinability ▲	Corrosion Resist. ▲	Magnetic ▲	Common CNC Uses ▲
303	Austenitic	90	35	HRB 96	78%	Medium	No	Shafts, fittings, nuts, bolts, screws, bushings
304	Austenitic	75	30	HRB 92	45%	High	No	Food equipment, tanks, brackets, enclosures
304L	Austenitic	70	25	HRB 88	45%	High	No	Welded assemblies, chemical tanks, piping
316	Austenitic	80	30	HRB 95	36%	Excellent	No	Marine hardware, medical devices, chemical processing
316L	Austenitic	75	25	HRB 90	36%	Excellent	No	Surgical implants, welded marine parts, pharma equipment
321	Austenitic	75	30	HRB 88	36%	High	No	Exhaust manifolds, expansion joints, high-temp brackets
347	Austenitic	75	30	HRB 88	36%	High	No	Jet engine parts, welded pressure vessels, refinery fittings
410	Martensitic	65	30	HRB 82	54%	Medium	Yes	Valve seats, pump shafts, fasteners, turbine blades
416	Martensitic	75	40	HRB 96	85%	Medium	Yes	Screw machine parts, gears, studs, high-volume turned parts
420	Martensitic	95	50	HRC 50 (hardened)	45%	Medium	Yes	Surgical tools, cutlery, molds, plastic injection dies
440C	Martensitic	110	65	HRC 58 (hardened)	25%	Medium	Yes	Bearings, knife blades, valve components, wear rings
17-4 PH (630)	Precipitation Hardening	190 (H900)	170	HRC 44	50%	High	Yes	Aerospace brackets, defense components, medical instruments
15-5 PH	Precipitation Hardening	190 (H900)	170	HRC 44	45%	High	Yes	Aircraft fittings, nuclear waste casks, high-strength shafts
2205	Duplex	90	65	HRC 31	30%	Excellent	Yes	Offshore oil equipment, chemical tanks, pressure vessels

No grades match your search. Try a different term or filter.

Tips for Machining Stainless Steel

Use sharp carbide tools. Dull tools cause work hardening fast, which ruins your part and your cutter.
Keep feeds high enough to stay under the work-hardened layer. Light cuts on stainless do more harm than good.
Use plenty of coolant. Stainless holds heat, and heat kills tool life. Flood coolant works best.
303 and 416 are the easiest grades to machine. Pick these when tight tolerances and fast cycle times matter most.
Austenitic grades (300 series) work harden quickly. Use rigid setups and avoid tool rubbing.
Machinability ratings are relative to B1112 free-machining steel at 100%. Lower numbers mean harder to cut.
Hardness values for 420 and 440C are shown in the hardened state. Annealed hardness is much lower.
17-4 PH and 15-5 PH tensile values are for the H900 heat treat condition. Other conditions give different results.

Frequently Asked Questions

What is the difference between 303 and 304 stainless steel?

303 has added sulfur. This makes it much easier to machine. It rates 78% on the machinability scale. 304 is harder to cut at 45%. But 304 resists corrosion better. Pick 303 when you need fast machining and tight tolerances. Pick 304 when the part must fight rust in harsh spots.

When should I use 316 stainless steel?

Use 316 when your part will touch salt water, chemicals, or acids. It has molybdenum added. This gives it excellent corrosion resistance. It is a top choice for marine hardware, medical devices, and chemical processing gear. 316L is the low-carbon version. Use 316L when you need to weld the part.

What is 17-4 PH stainless steel?

17-4 PH is a precipitation hardening stainless steel. You can heat treat it to very high strength. In the H900 condition, it reaches 190 ksi tensile strength. It also resists corrosion well. It is used in aerospace, defense, and medical parts that need both strength and rust resistance.

Which stainless steel grades are magnetic?

Martensitic grades like 410, 416, 420, and 440C are magnetic. Precipitation hardening grades like 17-4 PH and 15-5 PH are magnetic too. Duplex 2205 is also magnetic. Austenitic grades like 303, 304, 316, 321, and 347 are not magnetic when annealed. Cold working can make them slightly magnetic.

Ready to Start?

Get Your Parts Made Right

Upload your CAD file and get instant pricing. Prototypes ship in as few as 3 days.

Get an Instant Quote Email Us

No minimums · 100% Made in USA · Never brokered · Ships anywhere in the US

Stainless Steel Grades Chart

Tips for Machining Stainless Steel

Frequently Asked Questions

Related Resources

Steel Grades Chart | Properties, Strength & Uses Compared

Material Comparison Tool | Compare CNC Materials Side-by-Side

Material Hardness Chart | Brinell, Rockwell & Vickers Comparison

More Resources

Get Your Parts Made Right

Download PDF