Selection summary
Overview
SAE 1045 is a medium-carbon steel chemistry used for shafts, pins, gears, and machinery parts. Normalized, annealed, cold-finished, induction-hardened, and quenched-and-tempered conditions have substantially different strength, hardness, toughness, and machinability.
This page separates standard-oriented limits from typical reference data. Purchase acceptance comes from the ordered specification and certified material test report.
Names and systems
Identity & standards
Similar designations across ASTM, EN, JIS, and other systems are not automatically interchangeable. Product form and ordered standard control chemistry, properties, dimensions, condition, and testing.
Reference chemistry
Composition
| Element | Reference range | Why it matters |
|---|---|---|
| Carbon | 0.43–0.50% | Strength, hardness, and heat-treatment response |
| Manganese | 0.60–0.90% | Strength and hardenability support |
| Phosphorus / sulfur | SAE J403 limits | Cleanliness and machining behavior |
Concise grade-family reference only. Confirm every element limit against the current standard for the exact product ordered.
Condition matters
Reference properties
Normalizing, cold work, and quench-and-temper condition control
Use the ordered mechanical-property requirement and certified result
Typical medium-carbon steel reference value
Environment first
Corrosion behavior
No inherent atmospheric corrosion resistance.
Use a finish, coating, plating, lubricant, or controlled environment.
Temperature, concentration, deposits, crevices, stress, surface finish, cleaning, and fabrication quality can change service performance.
Service limits
Temperature & service
Temper condition and section size control performance after thermal exposure.
Delivery condition
Heat treatment & condition
1045 can be supplied hot rolled, normalized, annealed, cold finished, flame/induction hardened, or quenched and tempered; each condition produces a different property set.
Hardened depth and final hardness depend on section size, austenitizing, quench severity, tempering, and prior microstructure, so a chemistry designation cannot replace a heat-treatment specification.
Process route
Fabrication
Welding needs more care than low-carbon 1018/1020 because of carbon content and hardening risk.
Induction hardening can create a wear-resistant surface when case depth and hardness are specified.
Magnetic response: Ferromagnetic.
Decision boundaries
Comparisons & substitution
1045 offers higher carbon and potential strength/wear response than 1018/1020 but generally lower weldability and less case/core design flexibility.
4140 provides greater hardenability for thicker sections, while 1045 can remain economical for moderate sections and localized surface hardening.
Where it is used
Applications
Ordering scope
Product forms & standards
Hot-rolled or cold-finished bar under a product specification that invokes the required chemistry, dimensions, surface, and testing controls.
Wire rod, wire, tube, sheet, plate, or forgings require their own product specification; the SAE chemistry designation alone does not define delivery requirements.
Machined components must retain heat identity and condition records when chemistry, hardness, or heat treatment is acceptance-critical.
Decision support
Selection guidance
Choose this grade when
- Higher strength or surface-hardening response is needed without a highly alloyed steel.
- Heat treatment, section, hardness, and machining allowance are fully specified.
Review another grade when
- Deep hardenability, severe impact toughness, or heavy-section strength is required.
- Extensive welding makes a lower-carbon or different alloy system safer.
Before ordering
Procurement checklist
State the exact material and product specification, edition, grade, dimensions, tolerances, and delivery condition.
Require heat identity and a material test report showing chemistry, mechanical tests, and any ordered supplementary tests.
Confirm fabrication route, welding or heat treatment, inspection, marking, corrosion protection, export packing, and destination requirements.
State heat-treatment condition, hardness range, case depth if induction hardened, straightness, and machining allowance.
Traceable evidence