Steel A321 QT-33-38HRC
Hardness band
ASTM A321
Maximum practical through-hardened strength for 0.35 %C steel; limited to thin sections and applications tolerating reduced toughness.
Values for the QT-33-38HRC condition
Other A321 tempers and conditions
A321 is listed in 8 conditions; see the grade overview at A321.
- A
- HR
- N
- CD
- QT-22-26HRC
- IH
- QT-28-32HRC
- QT-33-38HRC
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition — choose for heavy machining, cold forming or when maximum ductility is needed before hardening. | 270 | 495 | 30 | 143 HB | 51 W/m·K |
HRDefault Hot rolled | Standard stocked plate condition — cheapest, adequate for weldments and machined parts of moderate duty. | 305 | 550 | 18 | 163 HB | — |
Normalized | Pick for uniform fine-grain structure, better toughness and predictable machining before final Q&T or for as-supplied service parts. | 345 | 585 | 25 | 170 HB | — |
Cold drawn | Bar/shaft stock with raised yield, close tolerance and good surface — use where no further heat treatment is planned. | 510 | 600 | 12 | 179 HB | — |
quenched and high-temperature tempered (~600 °C) | Use quenching plus high-temperature tempering near 600 °C for shafts and connecting parts that need 620 MPa yield with 20% elongation and remain reasonably machinable. | 620 | 800 | 20 | 24 HRC | 47 W/m·K |
Induction hardened | Use for journals, spline and cam surfaces needing wear resistance and compressive residual stress over a tough Q&T core. | 640 | 820 | 16 | 52 HRC | 9.5 % IACS |
quenched and tempered (~540 °C) | Choose tempering near 540 °C when moderately loaded shafts, pins and gear blanks in sections under about 40 mm need 780 MPa yield, accepting 17% elongation and slower machining. | 780 | 950 | 17 | 30 HRC | — |
QT-33-38HRCThis page quenched and low/medium tempered (~450 °C) | Maximum practical through-hardened strength for 0.35 %C steel; limited to thin sections and applications tolerating reduced toughness. | 950 | 1,120 | 14 | 35 HRC | — |
What is A321 QT-33-38HRC?
A321 QT-33-38HRC is A321 heat treated to QT-33-38HRC — maximum practical through-hardened strength for 0.35 %C steel; limited to thin sections and applications tolerating reduced toughness. A321 QT-33-38HRC has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,120 MPa (162 ksi) — stronger than 91% of steel grades. Elongation at break is 14% and the elastic modulus is 205 GPa (29.7 Msi). A321 QT-33-38HRC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). HR is the default condition FabDigit quotes; QT-33-38HRC is available on request or by drawing note.
Advantages
- High strength — 950 MPa (138 ksi), better than 91% of steel grades
- High electrical conductivity — 10.5 % IACS, better than 89% of steel grades
- Conducts heat well — 50 W/m·K (28.9 BTU/hr·ft·°F), better than 87% of steel grades
Limitations
- Difficult to machine — 37/100, worse than 81% of steel grades
- Low fracture toughness — 58 MPa·√m (52.8 ksi·√in), worse than 80% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
A321 QT-33-38HRC properties
Typical room-temperature values for A321 QT-33-38HRC; 15 are specific to this condition. Other listed values are A321 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A321 QT-33-38HRC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
A321 QT-33-38HRC has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,120 MPa (162 ksi) — stronger than 91% of steel grades. Elongation at break is 14% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A321 QT-33-38HRC is rated for continuous service to 400°C (752 °F). It conducts heat at 50 W/m·K (28.9 BTU/hr·ft·°F), better than 87% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
A321 QT-33-38HRC conducts electricity at 10.5 % IACS, better than 89% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of A321 QT-33-38HRC takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 28%.
Manufacturability6
A321 QT-33-38HRC's machinability is fair (37/100, worse than 81% of steel grades); weldability poor (25/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A321 QT-33-38HRC
Is A321 easy to machine?
Machines well in normalized or Q&T ≤30 HRC with carbide tooling; annealed material tends to smear, so prefer normalized structure and positive-rake geometry for good finish.
Can A321 be welded?
Weldable with low-hydrogen electrodes but CE ≈ 0.5 demands 150–250 °C preheat, controlled interpass and post-weld stress relief to avoid HAZ hardening and cold cracking.
Can A321 be formed, bent or molded?
Hot forge/roll at 1100–1200 °C; cold bending is limited — use generous bend radii (≥2t) or form in the annealed condition.
What surface finishes work on A321?
No inherent corrosion resistance: apply phosphate+oil, zinc plating, black oxide or paint; takes a fine mechanical polish and accepts nitriding or induction hardening for wear surfaces.
A321 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 |
|---|---|---|
| Cmedium-carbon range, GB/T 699 grade 35 / AISI 1035 | 0.32 – 0.4 | 0.35 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.5 – 0.8 | 0.65 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Crresidual | ≤ 0.25 | 0.1 |
| Niresidual | ≤ 0.3 | 0.1 |
| Curesidual | ≤ 0.25 | 0.1 |
| Fe | balance | — |
A321 QT-33-38HRC — frequently asked
What is A321 QT-33-38HRC used for?
A321 QT-33-38HRC is typically used for machine parts, medium-strength plate components, structural reinforcements and equipment bases. In short: mid-strength machinable plate; responds to induction hardening; needs preheat for welding.
What is the yield strength of A321 QT-33-38HRC?
A321 QT-33-38HRC has a typical yield strength of 950 MPa (138 ksi) and a tensile strength of 1,120 MPa (162 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is A321 QT-33-38HRC easy to machine?
Not especially — machinability is rated fair (37/100, worse than 81% of steel grades). Machines well in normalized or Q&T ≤30 HRC with carbide tooling; annealed material tends to smear, so prefer normalized structure and positive-rake geometry for good finish.
Can A321 QT-33-38HRC be welded?
Not readily — weldability is rated poor (25/100). Weldable with low-hydrogen electrodes but CE ≈ 0.5 demands 150–250 °C preheat, controlled interpass and post-weld stress relief to avoid HAZ hardening and cold cracking.
What surface finishes work on A321 QT-33-38HRC?
No inherent corrosion resistance: apply phosphate+oil, zinc plating, black oxide or paint; takes a fine mechanical polish and accepts nitriding or induction hardening for wear surfaces.
Can A321 QT-33-38HRC be formed, bent or molded?
Hot forge/roll at 1100–1200 °C; cold bending is limited — use generous bend radii (≥2t) or form in the annealed condition.
What is the maximum service temperature of A321 QT-33-38HRC?
A321 QT-33-38HRC is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A321-HR and A321-IH?
HR is the default condition — standard stocked plate condition — cheapest, adequate for weldments and machined parts of moderate duty. IH: use for journals, spline and cam surfaces needing wear resistance and compressive residual stress over a tough Q&T core. Yield strength is 305 MPa in HR versus 640 MPa in IH.
Sources
- GB/T 699 (grade 35) — SAC (2015)
- ASTM A321 Steel Bars, Carbon, Quenched and Tempered — ASTM (2016)
- ASTM A29/A29M 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.4: Heat Treating — ASM International (1991)
- Machining Data Handbook — machinability ratings vs AISI 1212 — Metcut Research (1980)
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.