1045 C45 S45C 1.1191 CK45 Round Steel Bar
Medium carbon engineering bar in 0-500mm diameter hot rolled black or cold drawn bright
Specifications
Steel Bar
41CrAlMo7 Nitriding Steel Round Bar for Gears and Valves
Nitrogen hardening chromium aluminium molybdenum bar from 5mm to 500mm diameter
41CrAlMo7 1.8509 round steel bar is a nitrogen hardening alloy steel with chromium aluminium and molybdenum that develops a hard nitrided case while keeping a tough core. It is specified by gear makers valve manufacturers and mould shops that need parts to hold a wear surface at working temperature rather than rely on a through hardened body. The bar is hot rolled from 5mm to 500mm diameter so a small valve stem and a heavy forging tool can be drawn from the same material specification. Ordering it with the equivalent designations recorded on the certificate saves the back and forth that starts when a drawing says 38CrMoAl and the stock label says 1.8509.
- Product Name — 41CrAlMo7 1.8509 Round Steel Bar
- Grade — 41CrAlMo7 1.8509 38X2MIOA E7140 SACM 645 40X2MI-O 905M39
- Material — 38CrMoAl 41CrAlMo7 1.8509 38X2MIOA E7140 SACM 645 40X2MI-O 905M39
- Standards — BS EN GB AISI ASTM DIN JIS
- Diameter — 5-500mm
Why It Is Specified
Key Benefits of 41CrAlMo7 1.8509 Round Steel Bar
Nitride Hardening Without a Through Hardened Core
The alloy is designed to take a nitrided case, so the working surface resists wear while the core keeps its toughness for shock and bending loads.
Hardenability Across the Full Diameter Range
The chemical composition gives consistent hardenability, which matters when the same grade has to be treated at 5mm and at 500mm section.
Holds Properties at Working Temperature
Heat resistance makes the grade a candidate for tools used in hot forming, where a plain carbon tool steel loses hardness after a few cycles.
Eight Equivalent Designations on One Certificate
38CrMoAl 41CrAlMo7 1.8509 38X2MIOA E7140 SACM 645 40X2MI-O and 905M39 describe the same steel. Drawings from different markets can be filled from one bar.
Machinable Before Nitriding
The grade machines well in the soft condition, so features are cut first and the nitride treatment is the last step before finish grinding.
Corrosion and Oxidation Resistance From the Alloy
Chromium and aluminium give the bar resistance to corrosion and oxidation, which helps on parts that sit in humid plant air between production runs.
Problems It Solves
What This Material Removes From Your Process
Wear Surfaces That Fail Before the Part Does
Through hardened parts either wear at the surface or crack in the body. A nitriding grade separates the two problems by putting hardness in the case and toughness in the core.
Tooling That Softens in Hot Work
Tools for hot forming lose hardness when the grade has no heat resistance. 41CrAlMo7 is used where the tool stays in contact with heated stock.
Matching a Drawing Designation to Available Stock
A buyer holding a drawing marked SACM 645 or 905M39 often cannot tell whether an offer of 1.8509 is the same material. The equivalents are stated on the certificate so the substitution is documented.
Two Suppliers for Small and Large Sections
Diameters from 5mm to 500mm come from one grade line, so a valve insert and a forging die block do not need separate sourcing.
Distortion in Late Stage Heat Treatment
Machining in the soft condition and nitriding afterwards keeps dimensional change small compared with quenching a finished part.
Application Scenarios
Where It Is Used
Gears and Shafts Under High Load
Drive gears and shafts where tooth flanks and journals need extreme wear resistance while the shaft body still has to bend without cracking.
Valve Components
Stems seats and internals for valves, machined from bar and nitrided so the sealing faces hold up against repeated cycling.
Plastic Molding Components
Mould bases and inserts where a nitrided surface resists the abrasion of filled resins and keeps the cavity dimension stable.
Automotive Drivetrain Parts
Crankshafts camshafts and transmission components produced from bar and surface hardened after machining.
Tools for Hot Forming
Forging and hot working tools that stay in contact with heated stock and need a grade that does not soften immediately.
Forged Tools and Industrial Machinery
Heavy duty machinery components taken from the larger diameters, forged to shape and then treated.
Who It Is For
Buyers Who Specify This Product
- Gear and shaft manufacturers buying nitriding bar for high load drivetrain parts
- Valve makers buying stem and internal component stock in a corrosion resistant alloy
- Mould shops buying bar for mould bases and inserts that will be nitrided
- Automotive tier suppliers buying crankshaft camshaft and transmission blanks
- Forging shops buying large diameter bar for hot forming tooling
- Distributors stocking a nitriding grade that answers DIN EN GB and JIS drawings
Technical Data
Specifications and Technical Features
Values below come from the product data published by Shandong Tianyu Metal Products. Confirm the exact grade and size against your order.
| Product Name | 41CrAlMo7 1.8509 Round Steel Bar |
|---|---|
| Grade | 41CrAlMo7 1.8509 38X2MIOA E7140 SACM 645 40X2MI-O 905M39 |
| Material | 38CrMoAl 41CrAlMo7 1.8509 38X2MIOA E7140 SACM 645 40X2MI-O 905M39 |
| Standards | BS EN GB AISI ASTM DIN JIS |
| Diameter | 5-500mm |
| Size | Customized |
| Technique | Hot rolled |
| Surface | Nature or painted |
| Application | Gears components for valves mechanical engineering tools for hot forming |
| Place of Origin | China |
| Processing Service | Bending welding decoiling cutting punching |
| Certificate | Mill test certificate |
| Sample | Available |
Technical Features
- Nitrogen hardening alloy steel with chromium aluminium and molybdenum
- Grades 38CrMoAl 41CrAlMo7 1.8509 38X2MIOA E7140 SACM 645 40X2MI-O and 905M39
- Standards BS EN GB AISI ASTM DIN and JIS
- Diameter 5-500mm or customized as required
- Technique hot rolled
- Surface supplied natural or painted
- Processing service bending welding decoiling cutting and punching
- Applications cover gears valve components mechanical engineering and hot forming tools
Materials
- Nitriding alloy steel 41CrAlMo7 to material number 1.8509
- Chromium aluminium and molybdenum alloying for case hardness and hardenability
- Supplied against the equivalents 38CrMoAl SACM 645 E7140 and 905M39
- Hot rolled bar with a natural or painted surface
Certification
- Mill test certificate supplied with each shipment
Manufacturing
How It Is Made and Processed
Melting and alloying to the 41CrAlMo7 composition
Hot rolling to the ordered diameter between 5mm and 500mm
Straightening and surface conditioning
Cutting to the ordered length
Optional bending welding decoiling and punching
Natural or painted surface before dispatch
Bundling marking and loading for export
Quality Control
Checks Before It Ships
- Mill test certificate issued with the chemical composition for the ordered heat
- Grade equivalents recorded on the certificate for drawing cross reference
- Diameter checked across the section before cutting
- Length and quantity verified against the order before bundling
- Surface inspected for scale and handling damage prior to packing
Customization
What We Can Change on Your Order
- Diameter selected anywhere between 5mm and 500mm
- Cut lengths supplied to your machining list
- Certificate marked with the designation used on your drawing
- Natural or painted surface depending on storage conditions
- Bending welding cutting and punching before shipment
- Mixed diameter consignments consolidated into one shipment
Comparison
41CrAlMo7 1.8509 Round Steel Bar Against the Alternatives
| Through hardened alloy steel such as quenched and tempered bar | A nitrided case adds surface hardness without heating the finished part to the quench temperature, so distortion stays lower on precision gears and mould inserts. |
|---|---|
| Case carburized low carbon steel | Nitriding runs at a lower temperature than carburizing and needs no quench afterwards, which suits parts already machined to close tolerance. |
| Plain medium carbon bar | The chromium aluminium molybdenum composition retains properties at working temperature, where a plain carbon grade softens in hot forming service. |
| Stainless bar for corrosion duty | 41CrAlMo7 offers corrosion and oxidation resistance with the strength and wear surface that mould and gear parts need, at a lower material cost than a comparable stainless section. |
Use Guide
Specifying Handling and Welding Notes
- Machine all features in the soft condition and leave grinding stock for the nitrided case
- Specify the nitriding depth with your treatment shop rather than assuming a standard case
- Allow for the case being thin and hard when planning any post treatment grinding
- Order the larger diameters as forged sections where the part geometry allows
- State the drawing designation so the certificate carries the equivalent your inspector expects
- Store bar off the ground and keep painted surfaces intact if material waits between production batches
Questions Buyers Ask
41CrAlMo7 1.8509 Round Steel Bar FAQ
What diameter range can you roll in 41CrAlMo7?
From 5mm to 500mm, and sizes outside that are customized as required. Tell us the finished part diameter and we will confirm the nearest bar size.
Is 1.8509 the same as 38CrMoAl and SACM 645?
Yes, they are equivalent designations for the same nitriding steel, along with 38X2MIOA E7140 40X2MI-O and 905M39. The equivalents are recorded on the mill test certificate.
Do you nitride the bar before shipping?
Bar is supplied hot rolled so you can machine it first. Nitriding is done after machining, which is the point of specifying this grade.
Can it be used for hot forming tools?
Yes. Heat resistance is one reason the grade is chosen for tools used in hot forming, alongside gears valve components and general mechanical engineering parts.
What certificate do you issue?
A mill test certificate covering the ordered grade and heat. Ask for the mill test certificate when you place the order so it travels with the material.
Can you cut the bar to our machining lengths?
Yes. Processing covers bending welding decoiling cutting and punching, so bar can arrive at billet length instead of full bars.
Are samples available before a production order?
Samples are available. Send the diameter and the length you need for trial machining and we will confirm what can be released.
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