Stainless Steel 440B seamless pipes and tubes fall in between 440A and 440C in terms of carbon content and hardness level. 440B contains 0.75% - 0.95% carbon along with 16% to 18% chromium, thus it provides better hardness than 440A, while being more tough as compared to 440C. Hence, it becomes suitable for applications where high wear resistance is required, but brittleness should be avoided. Amardeep Steel supplies SS 440B seamless tubes and hollows with EN 10204 3.1 mill test certificates, heat treatment records and full heat traceability. Compare our SS 440A seamless pipes and tubes and SS 440C seamless pipes and tubes, or see our SS 440 tubes.
What Are Stainless Steel 440B Seamless Pipes & Tubes?
Grade 440B hardens by heat treatment to a hardness suited to tools, bearings and valve parts. It is the middle choice of the 440 family when 440A is too soft and 440C is too brittle for the part.
How 440B Seamless Tube Is Produced
High carbon 440 grades are made mainly as bar, wire and billet, and no ASTM tube specification lists them. Seamless 440B tube is therefore produced to drawing, usually by piercing or boring hollow bar, and supplied annealed for machining. The final hardness comes from the buyer's own hardening and tempering after machining, or from heat treatment we arrange to the drawing.
SS 440B Seamless Tube Specifications
Parameter | Details |
|---|---|
Grade | Stainless Steel 440B (AISI 440B) |
UNS | S44003 |
Chemistry Basis | ASTM A276 / A580 limits for the grade; tube made to drawing or purchase specification |
Type | Seamless, hot finished or cold drawn, and machined hollows |
Size Range | To drawing or purchase specification |
Length | Random, fixed and cut lengths |
Supply Condition | Annealed for machining; hardened and tempered on request |
Test Certificate | EN 10204 3.1, with 3.2 available on request |
SS 440B Chemical Composition
Element | Content (%) |
|---|---|
Carbon (C) | 0.75 to 0.95 |
Chromium (Cr) | 16.00 to 18.00 |
Molybdenum (Mo) | 0.75 max |
Manganese (Mn) | 1.00 max |
Silicon (Si) | 1.00 max |
Phosphorus (P) | 0.040 max |
Sulfur (S) | 0.030 max |
SS 440B Mechanical Properties
Property | Value |
|---|---|
Typical hardness, annealed | 96 HRB |
Typical hardness, hardened and tempered at 315 degrees Celsius | 55 HRC |
Commonly specified hardness after heat treatment | 56 HRC min |
These are typical values from published data, not specification minimums. The hardness you receive depends on section size and on the hardening and tempering cycle, which is agreed with your order.
SS 440B Equivalent Grades
Standard | Designation |
|---|---|
UNS | S44003 |
AISI | 440B |
EN / Werkstoff No. | 1.4112 (X90CrMoV18), closest |
JIS | SUS440B |
GB | 8Cr17 |
Equivalent grades are close matches, not direct substitutes. Check the drawing before switching standards.
440A vs 440B vs 440C
Property | 440A | 440B | 440C |
|---|---|---|---|
Carbon | 0.60 to 0.75% | 0.75 to 0.95% | 0.95 to 1.20% |
Chromium | 16 to 18% | 16 to 18% | 16 to 18% |
Typical hardness, tempered at 315 degrees Celsius | 51 HRC | 55 HRC | 57 HRC |
Corrosion resistance | Best of the three | Middle | Lowest of the three |
Toughness | Highest | Middle | Lowest |
Carbon rises from 440A to 440C, which raises hardness and wear resistance but lowers corrosion resistance and toughness. See our SS 440 tubes for the full family and our SS 420C bars for a lower carbon martensitic option.
Applications of SS 440B Seamless Pipes and Tubes
- Cutting and measuring tools
- Bearing races and sleeves
- Valve parts and seats
- Wear resistant bushes
Testing and Documentation
Every order of SS 440B seamless tube goes through the checks below at our testing facility or approved third party labs.
- Chemical analysis and PMI
- Hardness test on each heat treatment lot
- Ultrasonic or eddy current testing on request
- Visual and dimensional inspection
Mill test certificates are issued to EN 10204 3.1, with 3.2 available on request. You can view our approvals on the certificates page.
Packing and Marking
Each length is marked with grade, size, heat number and heat treatment condition. Bores are oiled and capped. Tubes are packed in bundles or wooden boxes for export. Read more about our packing and despatch process.
Request a Quote for Stainless Steel 440B Seamless Pipes & Tubes
Send us the OD, ID or wall thickness, heat treatment condition, length and quantity, and our team will reply with price and delivery. Use the enquiry form or reach us through the contact page.
Frequently Asked Questions
What is Stainless Steel 440B?
Stainless Steel 440B (UNS S44003) is a martensitic stainless steel with 0.75 to 0.95% carbon and 16 to 18% chromium, hardenable by heat treatment.
What is the difference between 440A, 440B and 440C?
Carbon rises from 440A to 440C. 440B sits in the middle, harder than 440A and tougher than 440C.
What is the EN equivalent of 440B?
The closest EN grade is 1.4112 (X90CrMoV18). The JIS equivalent is SUS440B.
Is there an ASTM tube specification for 440B?
No. 440B is covered as bar and wire. Seamless 440B tube and hollows are produced to drawing.
