Martensitic Stainless 440C 51300 Series Thrust Ball Bearings
Grade, hardness, corrosion behavior, service temperature and the full bore range for this material.
Martensitic Stainless 440C 51300 Series Thrust Ball Bearings are made from AISI 440C = X105CrMo17 (1.4125), hardened and tempered — the only common stainless hard enough to form a rolling raceway. Corrosion behavior: good in water, steam, mild chemicals and food service; it is a hardenable stainless, so it holds less chromium in solution than 304 and will stain in standing chlorides. The material is magnetic, and the usable service range is about -30 °C to +180 °C in ordinary bearing service, the lubricant usually deciding before the steel does. In practice this material is the standard corrosion-resistant bearing steel; a stainless bearing is rated below the same envelope in GCr15, so take its load ratings from the stainless table and never from the chrome steel one.
Material
AISI 440C = X105CrMo17 (1.4125), hardened and tempered — the only common stainless hard enough to form a rolling raceway
Corrosion resistance
Good in water, steam, mild chemicals and food service; it is a hardenable stainless, so it holds less chromium in solution than 304 and will stain in standing chlorides
Magnetic response
Magnetic
Service temperature
about -30 °C to +180 °C in ordinary bearing service, the lubricant usually deciding before the steel does
Property figures are typical for the material. In an assembled bearing the lubricant, the seals and the cage frequently reach their limits before the material does, so check all four against the duty. Material certification is available on request for production orders.
In a 51300 series thrust ball bearings, Martensitic Stainless 440C is the ring and rolling element steel of the corrosion-resistant version. The grade is AISI 440C = X105CrMo17 (1.4125), hardened and tempered — the only common stainless hard enough to form a rolling raceway; it is magnetic, and its usable service range is about -30 °C to +180 °C in ordinary bearing service, the lubricant usually deciding before the steel does. This page covers what the material changes about the bearing, the limits it brings with it, and the sizes supplied.
Why Martensitic Stainless 440C for 51300 Series Thrust Ball Bearings
The standard corrosion-resistant bearing steel; a stainless bearing is rated below the same envelope in GCr15, so take its load ratings from the stainless table and never from the chrome steel one. In a 51300 series thrust ball bearings it is the ring and rolling element steel of the corrosion-resistant version.
It is the compromise that makes a corrosion-resistant rolling bearing possible: enough carbon to be hardened to a raceway hardness, enough chromium to resist water and mild chemicals. Everything else about the bearing — the envelope, the tolerance class, the clearance group — is unchanged.
Material Properties
Grade designation
AISI 440C = X105CrMo17 (1.4125), hardened and tempered — the only common stainless hard enough to form a rolling raceway
Magnetic response
Magnetic
Service temperature
About -30 °C to +180 °C in ordinary bearing service, the lubricant usually deciding before the steel does
Corrosion characteristic
Good in water, steam, mild chemicals and food service; it is a hardenable stainless, so it holds less chromium in solution than 304 and will stain in standing chlorides
Service Limits
A martensitic stainless bearing is rated below the same envelope in chrome steel and it is not stainless in the way 316 is: it is corrosion RESISTANT, and standing salt water, chlorides or long wet periods will still pit it. It is also softer at temperature than GCr15. Take the ratings from the stainless table, and where the environment is genuinely aggressive, consider a full ceramic bearing or a polymer housed unit instead.
Alternatives and When to Switch
If the load matters more than the corrosion, go back to GCr15 with the right seals and a corrosion-inhibiting grease — a sealed chrome steel bearing outlasts a stainless one in many "wet" applications that are only occasionally wet. If the corrosion matters more than the load, go past stainless: a full ceramic or a polymer-housed bearing does not corrode at all.
Sizes of 51300 Series Thrust Ball Bearings Available in Martensitic Stainless 440C
Designation
Bore d (mm)
Outer diameter D (mm)
Height H (mm)
Chamfer r min (mm)
51305
25
52
18
1
51306
30
60
21
1
51307
35
68
24
1
51308
40
78
26
1
51309
45
85
28
1
51310
50
95
31
1.1
51311
55
105
35
1.1
51312
60
110
35
1.1
51313
65
115
36
1.1
51314
70
125
40
1.1
51315
75
135
44
1.5
51316
80
140
44
1.5
51317
85
150
49
1.5
51318
90
155
50
1.5
51320
100
170
55
1.5
Other ways to specify the 51300 Series Thrust Ball Bearings
Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the designation snaps the other fields to that size's standard values; you can then override any individual value.
Sends the selected values to the quote form below.
Our facility
Held in production, not just on paper
The tolerances above are decided on the grinding and superfinishing lines in our own plant, and gauged on every ring rather than on a sample. A dimension is only worth quoting if it survives the process that produces it.
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The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.
Dimensions & Specifications (ISO 104 / DIN 711 / GB/T 301)
Designation
Bore d (mm)
Outer diameter D (mm)
Height H (mm)
Chamfer r min (mm)
51305
25
52
18
1
51306
30
60
21
1
51307
35
68
24
1
51308
40
78
26
1
51309
45
85
28
1
51310
50
95
31
1.1
51311
55
105
35
1.1
51312
60
110
35
1.1
51313
65
115
36
1.1
51314
70
125
40
1.1
51315
75
135
44
1.5
51316
80
140
44
1.5
51317
85
150
49
1.5
51318
90
155
50
1.5
51320
100
170
55
1.5
Video: Martensitic Stainless 440C 51300 Series Thrust Ball Bearings
Third-party video, selected automatically for this topic. It is not produced by Bushing Bearings and is not a specification source — use the tables on this page for dimensional data.
Frequently Asked Questions
What corrosion resistance does Martensitic Stainless 440C give?
Corrosion behavior: good in water, steam, mild chemicals and food service; it is a hardenable stainless, so it holds less chromium in solution than 304 and will stain in standing chlorides.
Why is Martensitic Stainless 440C used for this part?
It is the compromise that makes a corrosion-resistant rolling bearing possible: enough carbon to be hardened to a raceway hardness, enough chromium to resist water and mild chemicals. Everything else about the bearing — the envelope, the tolerance class, the clearance group — is unchanged.
What are the limits of Martensitic Stainless 440C?
A martensitic stainless bearing is rated below the same envelope in chrome steel and it is not stainless in the way 316 is: it is corrosion RESISTANT, and standing salt water, chlorides or long wet periods will still pit it. It is also softer at temperature than GCr15. Take the ratings from the stainless table, and where the environment is genuinely aggressive, consider a full ceramic bearing or a polymer housed unit instead.
What should I use instead of Martensitic Stainless 440C?
If the load matters more than the corrosion, go back to GCr15 with the right seals and a corrosion-inhibiting grease — a sealed chrome steel bearing outlasts a stainless one in many "wet" applications that are only occasionally wet. If the corrosion matters more than the load, go past stainless: a full ceramic or a polymer-housed bearing does not corrode at all.
How do I request a quotation?
Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.
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