Balls - Micro balls
Stainless steel balls
> The stainless steel balls offered by Preciball can be divided into three main families: austenitic, martensitic, and ferritic grades.
Austenitic stainless steel balls mainly include the well-known grades of the 300 series, such as AISI 304, 304L, 316, and 316L. These materials generally provide excellent corrosion resistance as well as good formability. Grades 304 and 316 are widely used in the food, pharmaceutical, and chemical industries.
In the annealed condition, these steels are generally considered non-magnetic. However, some grades may become slightly magnetic after cold working, forming, or machining. They cannot be hardened by heat treatment, but their mechanical properties can be improved through work hardening.
Martensitic stainless steel balls, such as AISI 420 and 440C, can be hardened by heat treatment. They combine high hardness, good wear resistance, and moderate to good corrosion resistance, depending on the grade and operating conditions.
They are ferromagnetic and are particularly suitable for applications requiring high mechanical strength, good wear resistance, and long service life. Typical applications include bearings, cutting instruments, and valves.
Ferritic stainless steel balls are ferromagnetic and offer good oxidation resistance as well as low susceptibility to stress corrosion cracking, particularly in certain chloride-containing environments. They cannot be hardened by heat treatment.
Their corrosion resistance mainly depends on their chromium, molybdenum, and other alloying element contents. Common ferritic grades generally exhibit lower corrosion resistance than austenitic grades.
| Specification | Hardness | Density |
|---|---|---|
| AISI 302 | 25–39 HRC | 7.93 |
| AISI 304 | 25–39 HRC | 7.93 |
| AISI 304L | 25–39 HRC | 7.93 |
| AISI 316 | 25–39 HRC | 7.98 |
| AISI 420A | env. 50–54 HRC | 7.75 |
| AISI 420B | env. 52–56 HRC | 7.75 |
| AISI 420C | env. 55–58 HRC | 7.75 |
| AISI 420D | env. 56–60 HRC | 7.75 |
| AISI 440C | 58–64 HRC | 7.75 |
Role of Carbon in Stainless Steel Balls :
The manufacturing of steel balls requires the presence of carbon. The higher the carbon content in stainless steel balls, the harder they become. Furthermore, this factor also influences their wear resistance.
Role of Niobium in Stainless Steel Balls: In ferritic stainless steels, the addition of niobium is one of the most effective methods for improving the high-temperature resistance of an alloy. This addition helps reduce corrosion in stainless steel balls, particularly in high-temperature operating environments, thereby acting as a stabilizing element. Niobium can also improve toughness, creep resistance, and resistance to thermal fatigue.
Role of Titanium: The addition of titanium mainly improves resistance to pitting corrosion and acts as a stabilizing element. Titanium is considered a stabilizer in stainless steel ball alloys.
Role of manganese in stainless steel balls: Manganese is often used as a replacement for nickel. By reacting with oxygen, it acts as a deoxidizer. It can influence the behavior of the steel, particularly its hardenability.
Role of chromium in stainless steel balls: Chromium is primarily used to increase the hardness and wear resistance of stainless steel balls. It is also known to protect the material against corrosion and oxidation. Steel containing more than 12% chromium is considered stainless steel.
Role of silicon in stainless steel balls: Silicon plays a deoxidizing role in steel. Additionally, its combination with other alloys enhances the steel’s wear resistance. Small amounts of silicon are added to steel to improve its corrosion resistance. Silicon is commonly added to stainless steel to improve its oxidation resistance.
Role of nickel in stainless steel balls: Nickel provides excellent ductility and toughness at very low temperatures. These properties are maintained even at cryogenic (extremely low) temperatures. Furthermore, nickel promotes the formation of an austenitic structure in stainless steel balls. It can also help improve corrosion resistance in certain environments, particularly in acidic media.
Role of molybdenum in stainless steel balls: Molybdenum is used in stainless steel in concentrations of up to 8%, but most commonly between 2% and 4%. Even at low concentrations, molybdenum significantly improves the resistance of stainless steels to uniform corrosion and, above all, to localized corrosion. It is particularly effective at enhancing resistance to pitting and crevice corrosion in chloride-bearing environments.
| Specification | Equivalence | C % | Si %max | Mn % max | P % max | S % max | Cr % | Mo % | Ni % | Cu% |
|---|---|---|---|---|---|---|---|---|---|---|
| AISI 302 | W.-Nr. 1.4310 ; AFNOR Z10CN18-09 / X10CrNi18-8 | 0.15 max | 1 | 2 | 0.045 | 0.03 | 17.00–19.00 | — | 8.00–10.00 | — |
| AISI 304 | W.-Nr. 1.4301 ; X5CrNi18-10 | 0.08 max | 1 | 2 | 0.045 | 0.03 | 18.00–20.00 | — | 8.00–11.00 | — |
| AISI 304L | W.-Nr. 1.4307 ; X2CrNi18-9 | 0.030 max | 1 | 2 | 0.045 | 0.015 | 17.50–19.50 | — | 8.00–10.50 | — |
| AISI 316 | W.-Nr. 1.4401 ; EN X5CrNiMo17-12-2 ; AFNOR Z6CND17-12 | 0.08 max | 1 | 2 | 0.045 | 0.03 | 16.00–18.50 | 2.00–3.00 | 10.00–13.00 | — |
| AISI 316L | W.-Nr. 1.4404 ; EN X2CrNiMo17-12-2 ; AFNOR Z2CND17-12 | 0.03 max | 1 | 2 | 0.045 | 0.03 | 16.00–18.50 | 2.00–3.00 | 10.00–13.00 11.00-14.00 | — |
| AISI 420A | W.-Nr. 1.4021 ; EN X20Cr13 ; AFNOR Z20C13 | 0.16–0.25 | 1 | 1.5 | 0.04 | 0.03 | 12.00–14.00 | — | — | — |
| AISI 420C | W.-Nr. 1.4034 ; EN X46Cr13 ; AFNOR Z44C14 / Z40C14 | 0.43–0.50 | 1 | 1 | 0.04 | 0.03 | 12.50–14.50 | — | — | — |
| AISI 430 | W.-Nr. 1.4016 ; AFNOR Z8C17 | 0.08 max | 1 | 1 | 0.04 | 0.03 | 16.00–18.00 | — | — | — |
| AISI 440B | W.-Nr. 1.4112 ; EN X90CrMoV18 ; AFNOR Z90CDV18 | 0.75–0.95 | 1 | 1 | 0.04 | 0.03 | 16.00–18.00 | 0.75 max | ||
| AISI 440C | W.-Nr. 1.4125 ; AFNOR Z100CD17 | 0.95–1.20 | 1 | 1 | 0.04 | 0.03 | 16.00–18.00 | 0.40-0,80 0.75 max | — | — |
| AISI 904L | W.-Nr. 1.4539 ; X1NiCrMoCu25-20-5 ; UNS N08904 | 0.020 max | 1 | 2 | 0.045 | 0.03 | 19.00–23.00 | 4.00–5.00 | 23.00–28.00 | 1.00–2.00 |