Steel 4330 · hardness band
Steel 4330 Q&T-120
Properties of the Q&T-120 condition, compared with the other 4330 tempers.
Balanced oilfield class for tool joints and downhole housings.
What is 4330 Q&T-120?
4330 Q&T-120 is 4330 heat treated to Q&T-120 — balanced oilfield class for tool joints and downhole housings. 4330 Q&T-120 has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 90% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi). 4330 Q&T-120 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). HR is the default condition FabDigit quotes; Q&T-120 is available on request or by drawing note.
Advantages
- High strength — 880 MPa (128 ksi), better than 90% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
4330 Q&T-120 properties
Typical room-temperature values for 4330 Q&T-120 — 10 properties are specific to this condition; the rest are grade-level values shared by every 4330 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
4330 Q&T-120 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
4330 Q&T-120 has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 90% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4330 Q&T-120 is rated for continuous service to 370°C (698 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical2
4330 Q&T-120 has an electrical resistivity of 2.2×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is not recommended (14/100), better than 70% of steel grades.
Sustainability4
Producing a kilogram of 4330 Q&T-120 takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 30%.
Manufacturability7
4330 Q&T-120's machinability is fair (47/100, worse than 58% of steel grades); weldability fair (40/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 4330 tempers and conditions
4330 is also supplied in 9 other conditions. The full side-by-side table is on the 4330 overview.
- HRDefaultCheapest mill form for parts that will be heat treated after rough machining or forging.600 MPa yield · 26 HRC
- Q&T-150Highest commercial strength level for weight-critical shafts and landing-gear type parts; watch notch sensitivity and hydrogen embrittlement.1,100 MPa yield · 39 HRC
- Q&TStandard stocked condition for drill-tool and machined structural parts needing high strength with good toughness.965 MPa yield · 34 HRC
- Q&T-130Most common 4330V drilling/aerospace forging class; high strength with still-good CVN.960 MPa yield · 34 HRC
- Q&T-120Balanced oilfield class for tool joints and downhole housings.880 MPa yield · 30 HRC
- Q&T-110Lower-strength sour-service oriented class; softest Q&T level with best impact toughness and best HIC/SSC margin.800 MPa yield · 26 HRC
- CDTight-tolerance small-diameter bar with raised yield strength; no further heat treatment.790 MPa yield · 29 HRC
- NormalizedUniform fine grain and predictable response before final hardening; used for large forgings.650 MPa yield · 28 HRC
- AnnealedPick for maximum machinability and cold working before final quench and temper.570 MPa yield · 210 HB
Working with 4330 Q&T-120
Is 4330 easy to machine?
Machine in the annealed or ≤32 HRC Q&T condition with rigid setups, carbide inserts and moderate speeds; above 38 HRC prefer grinding or ceramic/CBN tooling.
Can 4330 be welded?
Weldable by GTAW/GMAW with low-hydrogen or matching filler, 200–320 °C preheat, controlled interpass and a post-weld temper below the original tempering temperature.
Can 4330 be formed, bent or molded?
Hot forge 1100–1230 °C, finish above 950 °C, then normalize; cold forming is limited to the annealed state with generous radii.
What surface finishes work on 4330?
No anodizing — protect with manganese/zinc phosphate, black oxide, Zn-Ni or Cd plate; bake at ~190 °C after plating to relieve hydrogen, and shot peen fatigue-critical fillets.
4330 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 |
|---|---|---|
| C4330V modified | 0.28 – 0.33 | 0.3 |
| Mn | 0.75 – 1 | 0.88 |
| Si | 0.2 – 0.35 | 0.28 |
| Ni | 1.65 – 2 | 1.85 |
| Cr | 0.75 – 0.95 | 0.85 |
| Mo | 0.35 – 0.45 | 0.4 |
| Vpresent in 4330V / 4330M; omitted in plain 4330 | 0.05 – 0.1 | 0.07 |
| Pmax; ≤0.010 for VAR aerospace | ≤ 0.02 | — |
| Smax; ≤0.005 for sour service | ≤ 0.02 | — |
| Curesidual max | ≤ 0.35 | — |
| Fe | balance | — |
4330 Q&T-120 — frequently asked
What is 4330 Q&T-120 used for?
4330 Q&T-120 is typically used for drill collars and tool joints, downhole tool bodies, wellhead and valve bodies, aircraft landing gear components, high-strength forgings and heavy-duty shafts and gear blanks. In short: high-strength Cr-Mo-Ni bar.
What is the yield strength of 4330 Q&T-120?
4330 Q&T-120 has a typical yield strength of 880 MPa (128 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 90% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 4330 Q&T-120 easy to machine?
Reasonably — machinability is rated fair (47/100, worse than 58% of steel grades). Machine in the annealed or ≤32 HRC Q&T condition with rigid setups, carbide inserts and moderate speeds; above 38 HRC prefer grinding or ceramic/CBN tooling.
Can 4330 Q&T-120 be welded?
With care — weldability is rated fair (40/100). Weldable by GTAW/GMAW with low-hydrogen or matching filler, 200–320 °C preheat, controlled interpass and a post-weld temper below the original tempering temperature.
What surface finishes work on 4330 Q&T-120?
No anodizing — protect with manganese/zinc phosphate, black oxide, Zn-Ni or Cd plate; bake at ~190 °C after plating to relieve hydrogen, and shot peen fatigue-critical fillets.
Can 4330 Q&T-120 be formed, bent or molded?
Hot forge 1100–1230 °C, finish above 950 °C, then normalize; cold forming is limited to the annealed state with generous radii.
What is the maximum service temperature of 4330 Q&T-120?
4330 Q&T-120 is rated for continuous use to about 370°C (698 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 4330-HR and 4330-CR?
HR is the default condition — cheapest mill form for parts that will be heat treated after rough machining or forging. CR: thin flat product with good surface finish, normally re-heat-treated after forming. Yield strength is 600 MPa in HR versus 820 MPa in CR.
Can FabDigit make parts in 4330 Q&T-120?
Yes — 4330 Q&T-120 is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- AMS 6411 — Steel Bars, Forgings and Tubing 0.95Cr 1.8Ni 0.40Mo 0.08V (4330V) — SAE International (2019)
- ASTM A29/A29M — General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 19 — Fatigue and Fracture — ASM International (1996)
- MMPDS-17, low-alloy steel chapters — Battelle/FAA (2022)
- 4330V alloy steel bar and forging data — specialty bar producers (e.g. TimkenSteel/Latrobe-type datasheets) (2021)
- NACE MR0175 / ISO 15156 — Materials for use in H2S-containing environments — NACE/ISO (2015)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.