Question 1

What is an AISI 302 / 304 / 304L stainless steel ball?

Accepted Answer

An AISI 302 / 304 / 304L stainless ball is an austenitic, generally non-magnetic stainless ball made from iron-chromium-nickel alloy with 18 % chromium and 8-10 % nickel (the classic 18-8 / 304 family). 302 has slightly higher carbon and is the wire grade; 304 is the universal general-purpose grade; 304L is the low-carbon weld-friendly variant. Together they are the most widely used stainless balls in industry.

Question 2

What is the chemical composition of 302 / 304 / 304L?

Accepted Answer

302: ≤0.15 % C, 17-19 % Cr, 8-10 % Ni. 304: ≤0.08 % C, 18-20 % Cr, 8-10.5 % Ni. 304L: ≤0.03 % C, 18-20 % Cr, 8-12 % Ni. All variants contain ≤2 % Mn, ≤1 % Si, ≤0.045 % P, ≤0.03 % S, balance iron. The decreasing carbon improves weldability and post-weld corrosion resistance.

Question 3

How hard can 302 / 304 / 304L balls be?

Accepted Answer

Annealed 302 / 304 / 304L is around HRB 80 (≈ HRC equivalent 25). Cold work (heading, burnishing) raises hardness to HRB 90-HRC 35. None of these grades respond to heat treatment for additional hardness. For applications needing HRC 45+ with similar corrosion resistance, switch to 17-4PH, 440C, or ceramic balls.

Question 4

How corrosion resistant is 302 / 304 / 304L?

Accepted Answer

302 / 304 / 304L offer excellent general corrosion resistance in atmospheric, fresh-water, food, dairy, brewing, and mild chemical environments. Pitting resistance equivalent (PRE) is ~18. They do NOT match 316 in chloride-rich or marine settings; for that, upgrade to 316 / 316L with PRE 25+.

Question 5

Are 302 / 304 / 304L balls magnetic?

Accepted Answer

Annealed 302 / 304 / 304L is essentially non-magnetic (μ ≈ 1.005-1.02). Severe cold working may induce slight ferrite, giving weak magnetic response. If true non-magnetic behavior matters (sensors, medical imaging, electronics), specify an 'NM' tested lot or switch to 316L in fully annealed condition.

Question 6

Which standards apply to 302 / 304 / 304L stainless balls?

Accepted Answer

Compliance with ASTM A276, A479, A493, ISO 683-13, EN 10088-3 (1.4301, 1.4307, 1.4310), and ASTM A967 for passivation. ISO 3290 / DIN 5401 covers ball tolerances; EN 10204 3.1 mill certificates accompany each shipment. FDA, RoHS, REACH statements are available.

Question 7

What precision grades do 302 / 304 / 304L balls come in?

Accepted Answer

Stocked grades: G100, G200, G500, G1000. G40, G60 available on request with smaller lot inspection. G10-G25 grades are not practical for austenitic stainless at competitive price - use 440C or Si3N4 instead if you need that level of precision.

Question 8

What size range of 302 / 304 / 304L balls do you supply?

Accepted Answer

Stainless 302 / 304 / 304L balls cover 0.3 mm to 100 mm. The most common industrial sizes are 3, 4, 5, 6, 8, 10, 12.7, 19.05, 25.4 mm. Larger balls up to 300 mm are produced by forging. Miniature balls under 1 mm are popular for spray pumps, dispenser valves, and check-valve seats.

Question 9

What are 302 / 304 / 304L balls typically used for?

Accepted Answer

These alloys dominate food and beverage valves, dairy fittings, brewery and distillery piping, kitchen equipment, architectural hardware, household appliances, locks, jewelry, photosensitive elements, dispenser pumps, chemical pumps for non-corrosive fluids, and precision check-valve balls. 304 / 304L is the default 'food-grade stainless' the world over.

Question 10

304 vs 304L stainless ball - which is better?

Accepted Answer

Choose 304 for routine use. Choose 304L when balls are welded into assemblies, exposed to temperatures 425-870 °C for long periods, or specified for sanitary / biopharma weldments where post-weld intergranular corrosion is a concern. 304L has lower strength at high temp but better corrosion after welding.

Question 11

302 vs 304 stainless ball - which should I choose?

Accepted Answer

302 is the wire grade with slightly higher carbon and is the preferred raw stock for cold-headed balls. 304 is the universal stainless grade with broader corrosion resistance and certifications. For finished balls, the visible difference is small; we typically supply balls labeled as 304 even when the raw stock was 302 unless the customer specifies otherwise.

Question 12

What is the density of 302 / 304 / 304L?

Accepted Answer

Density is 7.93 g/cm³ (0.286 lb/in³) for all three. Slightly lower than 316 (7.98 g/cm³) and notably lower than chrome steel (7.81 g/cm³... actually about 2 % lighter than you might expect for so-called 'heavy' chrome steel - small but useful when calculating flange loads on stainless assemblies).

Question 13

How should 302 / 304 / 304L balls be cleaned?

Accepted Answer

Clean with warm water and a neutral pH detergent; rinse with deionized water and dry. Avoid chlorides, bleach, hydrochloric acid and steel wool. For passivation repair, soak in 10-25 % citric acid at 50-60 °C for 30 minutes, rinse, dry. Sanitize per ASME BPE for pharma and food duties.

Question 14

Are 302 / 304 / 304L balls formable?

Accepted Answer

Yes. Austenitic stainless is highly formable in the annealed state. Balls are typically cold-headed from wire then lapped to final dimension. For non-spherical shapes from ball stock (e.g., flats, half-spheres), 302 is preferred because of its slightly higher strength. 304 is preferred for visual, polished end products.

Question 15

What is the MOQ for 302 / 304 / 304L balls?

Accepted Answer

Stocked 304 balls (1-50 mm) ship with 100 kg MOQ. Custom sizes, 304L or non-standard precision require 200-500 kg. Sample boxes of 100-200 pieces are available ex-stock against a freight-collect account.

Question 16

What is the lead time for 302 / 304 / 304L balls?

Accepted Answer

Stocked sizes dispatch in 5-7 business days. Custom diameters, mirror finish, or special passivation need 15-25 days. Repeat orders run 10-20 days. We confirm the ship date in the order acknowledgement.

Question 17

What certificates ship with 302 / 304 / 304L balls?

Accepted Answer

Mill certificate EN 10204 3.1 covering chemical analysis and mechanical properties is included. Dimensional and passivation certificates per ASTM A967 are issued on request. Compliance statements cover FDA, RoHS, REACH, EU 1935/2004. Pharma or food audits include 3.2 witnessed inspection by SGS / BV / TUV.

Question 18

How are 302 / 304 / 304L balls packaged?

Accepted Answer

Vacuum foil with desiccants and oxygen absorber, packed inside food-grade PE bags in PE-lined cartons (20-25 kg) or drums (50-200 kg). For clean-room or medical orders, double-bag with nitrogen flush and tamper-evident seals are available. ISPM-15 heat-treated pallets for export.

Question 19

What determines 302 / 304 / 304L ball pricing?

Accepted Answer

Price drivers are grade (302 vs 304 vs 304L), diameter, precision grade, surface finish, lot size, and LME nickel surcharge. 304 typically sells near 80 % of 316 price for the same diameter and grade. 304L carries 5-10 % premium due to additional steelmaking control.

Question 20

Why is 304 the world default stainless?

Accepted Answer

304 became the global default because it hits the sweet spot - more corrosion-resistant than 430 / 420, less expensive than 316, easy to weld, polish, machine and certify. For the vast majority of indoor, atmospheric, food-contact and mild-chemical uses 304 is fully adequate. We recommend upgrading to 316 only when chloride or salt is involved.