SAE 4145 is a chromium-molybdenum alloy steel with 0.43–0.48% carbon, 0.75–1.00% manganese, 0.80–1.10% chromium and 0.15–0.25% molybdenum. The higher carbon gives deeper hardening than 4140 and 4130. It is best known for oilfield drill collars and tools, and is also used for heavy shafts, gears, tool joints, couplings and flanges.
OneKaizen supplies SAE 4145 as rolled round bars (Ø 16–500 mm), bright bars (round Ø 8–160 mm), forged bars (round Ø 250–1,030 mm), shafts (Ø 25–500 mm) and special forgings, sourced from Indian and international mills and forges. Delivery condition is your choice: hot rolled, annealed, quenched and tempered (+QT), cold drawn or peeled and turned. Oilfield bars can be supplied quenched and tempered to 285–341 HB. OneKaizen also machines parts to drawing through partner machine shops.
EQUIVALENT GRADES
SAE 4145 Equivalents
Direct means the same grade under another name. Close means the same alloy concept with slightly different limits, commonly substituted. Approximate means similar use with real differences: check with us before substituting.
| Standard | Designation | Match |
|---|---|---|
| EN | 50CrMo4 (1.7228) | Approximate |
| DIN W.Nr. | 1.7228 | Approximate |
| AISI/SAE | 4145 | Direct |
| UNS | G41450 | Direct |
| JIS | SCM445 | Close |
| KS | SCM445 | Close |
SAE 4145 Chemical Composition
Per SAE J404 (SAE 4145)
| Element | Range, wt % | Range chart |
|---|---|---|
| C | 0.43 – 0.48 | |
| Si | 0.15 – 0.35 | |
| Mn | 0.75 – 1 | |
| P | ≤ 0.035 | |
| S | ≤ 0.04 | |
| Cr | 0.8 – 1.1 | |
| Mo | 0.15 – 0.25 |
SAE 4145 and Its Equivalents: Chemical Composition
Equivalent grades are written to different standards, so their limits differ slightly. Use the column for the standard on your drawing or purchase order.
| Element | SAE 4145 SAE J404 | SCM445 JIS G4053 |
|---|---|---|
| C % | 0.43–0.48 | 0.40–0.48 |
| Si % | 0.15–0.35 | 0.15–0.35 |
| Mn % | 0.75–1.00 | 0.60–0.85 |
| P % | ≤ 0.035 | ≤ 0.03 |
| S % | ≤ 0.04 | ≤ 0.03 |
| Cr % | 0.80–1.10 | 0.90–1.20 |
| Mo % | 0.15–0.25 | 0.15–0.30 |
Delivery Condition and Heat Treatment
SAE 4145 is delivered hot rolled, annealed, quenched and tempered (+QT), cold drawn or peeled and turned. For oilfield work the usual condition is quenched and tempered to 285–341 HB. Tell us your hardness or strength requirement and we confirm what the mill can supply.
The tempering temperature sets the final strength and toughness. Heavy sections harden deeper than in 4130 because of the higher carbon, but they need controlled heating and cooling to avoid cracking.
Welding 4145 is difficult because of its carbon content. It needs preheat, low hydrogen practice and post-weld heat treatment. If the part must be welded, SAE 4130 is the easier choice.
What We Supply SAE 4145 In
Where SAE 4145 Is Used
Industries: Oil and gas, Drilling equipment, Mining, Heavy machinery, Power transmission
Compare SAE 4145 with Similar Grades
SAE 4145 Questions
Is SAE 4145 the same as SCM445?
They are close, not identical. JIS SCM445 has a similar carbon range but slightly higher chromium (see the table above). Tell us if your drawing needs the exact JIS or SAE chemistry.
Is SAE 4145 the same as 50CrMo4?
No. EN 50CrMo4 (1.7228) is only an approximate match, with a higher carbon range. It is often offered against 4145 orders, but confirm that your specification allows it.
What is the difference between SAE 4145 and EN19 (4140)?
EN19 has slightly lower carbon than 4145, which has 0.43–0.48%. 4145 hardens deeper, which suits large drill collars and heavy shafts. EN19 is easier to machine and weld.
Can SAE 4145 be heat treated or welded?
It is supplied quenched and tempered, and can be heat treated further. Welding is difficult and needs preheat, low hydrogen practice and post-weld heat treatment.
What is SAE 4145 used for?
Oilfield drill collars and tools, heavy shafts, gears, tool joints, couplings and flanges.
What is the minimum order for SAE 4145?
3 tonnes, flexible depending on size and your situation. Send us your size, condition and quantity and we confirm availability and delivery.
What is SAE 4145 equivalent to?
SAE 4145 is the same grade as AISI/SAE 4145, UNS G41450. Close equivalents are JIS SCM445, KS SCM445.
In which forms do you supply SAE 4145?
OneKaizen supplies SAE 4145 as Round Bars, Bright Bars, Forged Bars, Shafts, Forgings & Special Components, delivered across India and exported to buyers abroad.
Do you supply SAE 4145 with a mill test certificate?
Yes. Every lot ships with an EN 10204 3.1 mill test certificate showing chemistry and mechanical properties, traceable to the heat number.
Data compiled by the OneKaizen metallurgy team from the standards named above. Updated 27 October 2026. Equivalents are nearest matches; confirm critical substitutions against the governing standard and mill certificate.