Steel SCr445
JIS SCr445 · AISI/SAE 5145
SCr445 is a 0.45 % carbon chromium alloy steel from the JIS SCr family, equivalent to AISI 5145 and 45Cr, strengthened by through-hardening rather than carburizing.
Reference datasheet — SCr445 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the QT condition
SCr445 tempers and conditions
SCr445 is supplied in 10 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition — pick for heavy machining, cold forming or deep-hole drilling before hardening. | 400 | 700 | 22 | 197 HB | — |
Hot rolled | Cheapest mill condition for stock that will be re-heat-treated after machining. | 480 | 800 | 18 | 21 HRC | — |
Normalized | Uniform fine pearlitic structure for forgings before final machining or hardening. | 540 | 870 | 17 | 25 HRC | — |
Cold drawn | Bright, close-tolerance bar for shafts machined without further heat treatment. | 750 | 900 | 10 | 26 HRC | 8 % IACS |
high-temper condition | Toughness-biased temper (≈600 °C) for large shafts and impact-loaded parts. | 810 | 980 | 16 | 30 HRC | 8 % IACS |
QTDefault Quenched and tempered | Standard supply/heat-treat condition: ≥980 MPa tensile with usable toughness for shafts and gears. | 860 | 1,030 | 14 | 32 HRC | — |
Induction hardened | Choose for journals, splines and gear teeth needing 55+ HRC wear surface with a tough 30 HRC core. | 860 | 1,030 | 12 | 57 HRC | 8 % IACS |
medium temper | Balanced strength/toughness temper for gears, couplings and high-strength fasteners. | 960 | 1,120 | 14 | 34 HRC | 8 % IACS |
low temper, high strength | Maximum through-hardened strength for wear-loaded shafts and pins; reduced toughness, grind after heat treat. | 1,150 | 1,300 | 11 | 40 HRC | — |
As-quenched | Intermediate state only — must be tempered promptly; maximum hardness but brittle and crack-prone. | 1,600 | 2,000 | 2 | 58 HRC | 6 % IACS |
What is SCr445?
SCr445 is a 0.45 % carbon chromium alloy steel from the JIS SCr family, equivalent to AISI 5145 and 45Cr, strengthened by through-hardening rather than carburizing. It is chosen when higher core strength than SCr440 is needed in shafts, gears and fasteners, and is available hot-rolled, annealed, normalized, cold-drawn and quenched-and-tempered to defined hardness bands (28-32, 32-36 and 38-42 HRC) as bar and forging stock. The default Q&T condition gives 860 MPa yield, 1030 MPa tensile, 14 % elongation at 302 HB / 32 HRC, with service limited to about 350 °C. Weldability is poor at this carbon level and there is no inherent corrosion resistance; SCM440 is the usual alternative where deeper hardenability or easier welding is needed. SCr445 has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,425°C (2,597 °F). SCr445 has a yield strength of 860 MPa (125 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 89% of steel grades. Elongation at break is 14% and the elastic modulus is 207 GPa (30 Msi).
What is SCr445 used for?
- shafts
- gears
- spring collars
- high-strength bolts
Advantages
- High strength — 860 MPa (125 ksi), better than 89% of steel grades
Limitations
- Limited formability — 20/100, worse than 80% of steel grades
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 78% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
SCr445 properties
Typical room-temperature values for SCr445-QT; bars are the position among steel grades.
Physical3
SCr445 has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
SCr445 has a yield strength of 860 MPa (125 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 89% of steel grades. Elongation at break is 14% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
SCr445 is rated for continuous service to 350°C (662 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
SCr445 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SCr445 takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability6
SCr445's machinability is fair (42/100, worse than 73% of steel grades); weldability poor (25/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. SCr445 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SCr445
Is SCr445 easy to machine?
Machine in the annealed or normalized state (≤229 HB) with carbide tooling; above 32 HRC expect reduced speeds and finish by grinding.
Can SCr445 be welded?
Poor weldability at 0.45 % C — preheat 250–350 °C, low-hydrogen consumables and immediate post-weld temper are mandatory to avoid HAZ cracking.
Can SCr445 be formed, bent or molded?
Hot forge 1100–1200 °C then normalize; cold forming is limited to mild straightening — bend only in the annealed condition with generous radii.
SCr445 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CJIS G 4053 SCr445 | 0.43 – 0.48 | 0.45 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Cr | 0.9 – 1.2 | 1.05 |
| Niresidual | ≤ 0.25 | |
| Curesidual | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on SCr445?
No natural corrosion resistance: use black oxide, phosphate + oil, zinc/Zn-Ni plating (bake against hydrogen embrittlement above 1000 MPa) or paint; grinds and polishes well after hardening.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel SCr445 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- AISI / SAE
- 5145
- Similar grades
- 45Cr
How much does SCr445 cost?
SCr445 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
SCr445 — frequently asked
What is SCr445 used for?
SCr445 is typically used for shafts, gears, spring collars and high-strength bolts. In short: higher-strength SCr440 upgrade; through-hardening chromium steel; strength before weldability.
What is the yield strength of SCr445?
SCr445 has a typical yield strength of 860 MPa (125 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 89% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is SCr445 easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Machine in the annealed or normalized state (≤229 HB) with carbide tooling; above 32 HRC expect reduced speeds and finish by grinding.
Can SCr445 be welded?
Not readily — weldability is rated poor (25/100). Poor weldability at 0.45 % C — preheat 250–350 °C, low-hydrogen consumables and immediate post-weld temper are mandatory to avoid HAZ cracking.
What surface finishes work on SCr445?
No natural corrosion resistance: use black oxide, phosphate + oil, zinc/Zn-Ni plating (bake against hydrogen embrittlement above 1000 MPa) or paint; grinds and polishes well after hardening.
Can SCr445 be formed, bent or molded?
Hot forge 1100–1200 °C then normalize; cold forming is limited to mild straightening — bend only in the annealed condition with generous radii.
What is the maximum service temperature of SCr445?
SCr445 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SCr445-QT and SCr445-Q?
QT is the default condition — standard supply/heat-treat condition: ≥980 MPa tensile with usable toughness for shafts and gears. Q: intermediate state only — must be tempered promptly; maximum hardness but brittle and crack-prone. Yield strength is 860 MPa in QT versus 1,600 MPa in Q.
How much does SCr445 cost?
SCr445 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- JIS G 4053 — Low-alloyed steels for machine structural use — JSA (2016)
- GB/T 3077 — Alloy structural steels (45Cr) — SAC (2015)
- ASTM A29/A29M — Steel bars, carbon and alloy (5145/5147) — ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook (machinability ratings, heat treatment of Cr steels) — Industrial Press (2020)
- Mysteel / 1688 alloy round bar spot quotations (45Cr) — Mysteel (2025)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.