Key takeaways
- Treat CK45, C45/C45E, and SAE 1045 as separate routes until purchaser approval.
- A chemistry designation does not fix bar form, condition, dimensions, mechanical evidence, or certificate content.
- Match incoming bar state to machining and later treatment before choosing the route.
- Require alternatives to show standards, product requirements, deviations, and evidence rather than claiming equivalence.
Why buyers choose CK45 / 1045
The product page describes CK45 / 1045 as a medium carbon steel used for mechanical components requiring strength, wear resistance, and practical post-processing. It is often reviewed when machinability and processing flexibility are important.
Common application fit
CK45 / 1045 can be considered for cylinder rods, general shafts, gears, bolts, and mechanical parts. Buyers should connect the choice to the actual part route rather than treating it as a simple commodity bar.
Delivery and processing questions
Useful RFQs specify whether the buyer needs hot rolled, heat-treated, peeled, machined, or another prepared condition. Surface condition and straightness can matter when the material moves into turning, polishing, or rod preparation.
When to review alternatives
If the application requires higher hardenability, higher toughness, or more demanding load conditions, buyers may also review alloy grades such as 40Cr or 42CrMo4 / 4140 with the supplier.
Start from the drawing designation and intended route
Legacy drawings may say CK45 while current procurement discussions use C45, C45E, or SAE 1045. Do not normalize those labels in the purchase order without an engineering decision. ISO 683-1 supplies a product route for covered direct-hardening non-alloy steels, while SAE J403 defines a carbon-steel chemistry route. Their designation systems, product scope, delivery conditions, section rules, sampling, and purchaser options are not automatically interchangeable.
Compare complete procurement routes, not names
Use the table to assign the controlling document and close every field that a grade shorthand leaves open.
| Route question | Buyer must state | Supplier must return | Approval boundary |
|---|---|---|---|
| Designation basis | Drawing term, required standard and edition, exact grade, and precedence | Quoted identity and any interpreted legacy wording | No cross-standard substitution without written engineering approval |
| Product form | Hot-wrought or cold-finished route, ordered dimensions, tolerance, surface, and length | Applicable product specification and proposed manufacturing route | SAE chemistry alone is not a complete bar product order |
| Material state | Delivered thermal condition, machining stock, later treatment, and represented section | Condition, lot model, test representation, and route exceptions | Evidence applies only to the declared delivered state and representation |
| Inspection evidence | Chemistry, ordered mechanics, dimensions, surface, marking, certificate, and traceability | Actual results, heat and lot links, deviations, and report register | Buyer accepts only the evidence listed in the approved order |
Review the licensed product and chemistry standards, drawing conversion record, dimensions, condition, testing, and deviations together. Only accepted order terms define the requirements for a specific supply.
Fix hot-wrought or cold-finished product requirements
When an SAE 1045 route is allowed, pair the chemistry designation with an applicable product specification and explicit order requirements. ASTM A29/A29M provides general requirements for hot-wrought steel bars when invoked by the applicable route. ASTM A108 covers cold-finished carbon and alloy steel bars. Neither removes the need to state size, tolerance, surface condition, straightness where controlled, end condition, test scope, supplementary requirements, marking, and documentation.
Cold-finished, peeled, ground, and machined are not interchangeable. Identify the supplied surface and machining allowance, then connect them to later treatment and final geometry. Ask the supplier to disclose straightening, thermal operations, repair, or subcontracted finishing after the state represented by testing. List exclusions and alternatives line by line so price differences are not mistaken for technical equivalence.
Worked RFQ example for a controlled alternative
Write the required route first and permit an SAE offer only as a separately priced deviation. This keeps a buyer from receiving an unreviewed substitution hidden behind an equivalent-grade statement.
Leave property targets in the approved drawing or schedule rather than importing typical catalog values.
Item: Medium-carbon steel round bars for [part and drawing revision], [size and quantity]
Required route: [C45 or C45E] to ISO 683-1:2016, [condition and surface]; legacy CK45 note retained as drawing reference
Alternative route: SAE 1045 to SAE J403_202402 plus [ASTM hot-wrought or cold-finished product basis], quoted separately
Comparison: Supplier to map designation, chemistry route, product form, condition, dimensions, testing, marking, documents, and every deviation
Downstream work: Buyer performs [machining and treatment]; supplied stock and material state must support the approved process plan
Inspection: Requirements and sampling per attached schedule; actual results linked to heat and represented lot
Approval: No alternative manufacture until the purchaser signs the material-conversion and deviation record
Only accepted order terms define the requirements for a specific supply.CK45 / 1045 round bar selection buyer questions
When should buyers review CK45 / 1045 round bar?
Buyers often review CK45 / 1045 when the part route needs medium carbon steel with practical machinability, balanced strength, and suitable processing details for shafts, rods, gears, bolts, or mechanical parts.
When is CK45 / 1045 suitable for industrial round bar buyers?
CK45 / 1045 is often reviewed for medium-carbon steel parts where machinability, moderate strength, and practical processing matter. Buyers should still confirm grade standard, delivery condition, surface route, inspection requirement, and final application with the request.
What should CK45 / 1045 buyers clarify in an RFQ?
Buyers should clarify whether CK45, C45, or AISI 1045 is required, plus size, quantity, length, delivery condition, machining or surface route, certificate requirement, destination, and whether the bar is for shafts, rods, gears, or fasteners.
CK45 / 1045 round bar selection RFQ checklist
- Required standard and accepted cross-reference grade
- Diameter, length, quantity, and tolerance needs
- Required surface condition and straightness expectation
- Whether heat treatment or machining preparation is needed
- End application and downstream process
- Inspection documents required for incoming quality review
- Exact drawing designation, conversion record, controlling standard, edition, and grade
- Hot-wrought, cold-finished, peeled, ground, or machined product route
- Delivered thermal condition, represented section, machining stock, and later treatment
- Dimensions, tolerance, straightness, surface, ends, marking, and packing requirements
- Ordered tests, sampling, actual results, heat and lot traceability, and certificate
- Separate alternative price, clause comparison, deviations, and written approval point
References
- ISO 683-1:2016 Heat-treatable steels — Part 1: Non-alloy steels for quenching and tempering
Supports: Official product, delivery-condition, and size-bounded route for covered non-alloy steels including C45 and C45E.
Limitation: The public catalog does not authorize a CK45 conversion or make ISO grades equivalent to an SAE chemistry designation.
- SAE J403_202402 Chemical Compositions of SAE Carbon Steels
Supports: Defines the SAE carbon-steel chemistry framework used when SAE 1045 is proposed as the material designation.
Limitation: SAE J403 does not define a complete bar product, condition, dimensions, mechanical properties, inspection, or certification route.
- ASTM A29/A29M-23 General Requirements for Steel Bars
Supports: Provides official general-requirements context for hot-wrought carbon and alloy steel bars when invoked by the order route.
Limitation: It does not independently select the grade, condition, properties, dimensions, testing, or application suitability for SAE 1045.
- ASTM A108-24 Standard Specification for Steel Bar, Carbon and Alloy, Cold-Finished
Supports: Provides official product-scope context for cold-finished carbon and alloy steel bars and supplementary order requirements.
Limitation: It does not make cold-finished, peeled, ground, or machined routes interchangeable or approve a cross-standard grade conversion.
Revision note: Expanded selection guidance from grade-name comparison to complete product-route control, including legacy designation governance, a buyer table, two physical-context figures, and a worked alternative RFQ.
Inquiry support
Send grade, size, delivery condition, inspection needs, and destination.
JOTAIN can review the stated grade, size, delivery condition, processing route, inspection requirements, and export details against the project requirement.