Martensitic Stainless 440C 51200 Series Thrust Ball Bearings
Grade, hardness, corrosion behavior, service temperature and the full bore range for this material.
Martensitic Stainless 440C 51200 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 51200 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 51200 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 51200 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
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.
What the Material Changes About the Bearing
The envelope is unchanged and the bearing drops into the same seat, but the load ratings are not the chrome steel ratings and must not be carried across. Expect a lower rating, a slightly lower temperature ceiling, and — in exchange — a bearing that survives the wash, the condensation or the food process that would rust a standard one.
Sizes of 51200 Series Thrust Ball Bearings Available in Martensitic Stainless 440C
Designation
Bore d (mm)
Outer diameter D (mm)
Height H (mm)
Chamfer r min (mm)
51200
10
26
11
0.6
51201
12
28
11
0.6
51202
15
32
12
0.6
51203
17
35
12
0.6
51204
20
40
14
0.6
51205
25
47
15
0.6
51206
30
52
16
0.6
51207
35
62
18
1
51208
40
68
19
1
51209
45
73
20
1
51210
50
78
22
1
51211
55
90
25
1
51212
60
95
26
1
51213
65
100
27
1
51214
70
105
27
1
51215
75
110
27
1
51216
80
115
28
1
51217
85
125
31
1
51218
90
135
35
1.1
51220
100
150
38
1.1
Other ways to specify the 51200 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
Where these dimensions are actually made
Ring forging, heat treatment, raceway grinding and superfinishing all happen under one roof, so a bore tolerance and a clearance group are set by processes we control and can evidence, not by whichever supplier had stock.
Request a Quote
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)
51200
10
26
11
0.6
51201
12
28
11
0.6
51202
15
32
12
0.6
51203
17
35
12
0.6
51204
20
40
14
0.6
51205
25
47
15
0.6
51206
30
52
16
0.6
51207
35
62
18
1
51208
40
68
19
1
51209
45
73
20
1
51210
50
78
22
1
51211
55
90
25
1
51212
60
95
26
1
51213
65
100
27
1
51214
70
105
27
1
51215
75
110
27
1
51216
80
115
28
1
51217
85
125
31
1
51218
90
135
35
1.1
51220
100
150
38
1.1
Video: Martensitic Stainless 440C 51200 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
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.
Does Martensitic Stainless 440C change the dimensions or the rating?
The envelope is unchanged and the bearing drops into the same seat, but the load ratings are not the chrome steel ratings and must not be carried across. Expect a lower rating, a slightly lower temperature ceiling, and — in exchange — a bearing that survives the wash, the condensation or the food process that would rust a standard one.
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.
Need a bearing quote or a spec sheet?Message our engineers on WhatsApp — send a drawing or DIN number and get pricing back fast.Start WhatsApp Chat →
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