Stainless Steel CB30-HT
Heat-treated state · default condition
UNS J91803 · ASTM A743 Grade CB30
HT = heat treated (annealed ≈790 °C min, air cooled) per ASTM A743
Standard supply condition for A743 CB-30 castings: best combination of corrosion resistance and machinability.
Values for the HT condition
Other CB30 tempers and conditions
CB30 is listed in 3 conditions; see the grade overview at CB30.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Only for non-critical, non-corrosive duty; grain-boundary carbides lower ductility and corrosion resistance, so A743 does not accept it for service. | 400 | 620 | 8 | 17 HRC | 2.5 % IACS |
Stress relieved | Applied after weld repair of CB-30 castings to restore ductility and reduce cracking risk in service. | 400 | 640 | 14 | 190 HB | 2.5 % IACS |
HTDefaultThis page Heat treated (annealed ≈790 °C min, air cooled) per ASTM A743 | Standard supply condition for A743 CB-30 castings: best combination of corrosion resistance and machinability. | 415 | 655 | 15 | 13 HRC | 2.5 % IACS |
What is CB30-HT?
CB30-HT is CB30 heat treated to HT — standard supply condition for A743 CB-30 castings: best combination of corrosion resistance and machinability. CB30-HT has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 62% of stainless steel grades. Elongation at break is 15% and the elastic modulus is 200 GPa (29 Msi). CB30-HT has a density of 7.53 g/cm³ (0.272 lb/in³), lighter than 99% of stainless steel grades. It melts at 1,425°C (2,597 °F).
Advantages
- Low embodied carbon — 3.6 kg CO₂/kg, better than 83% of stainless steel grades
- Conducts heat well — 23 W/m·K (13.3 BTU/hr·ft·°F), better than 78% of stainless steel grades
Limitations
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 95% of stainless steel grades
- Limited formability — 10/100, worse than 95% of stainless steel grades
- Limited ductility — 15%, worse than 89% of stainless steel grades
- Hard to polish — 55/100, worse than 89% of stainless steel grades
- Difficult to weld — 30/100, worse than 88% of stainless steel grades
CB30-HT properties
Typical room-temperature values for CB30-HT; 23 are specific to this condition. Other listed values are CB30 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CB30-HT has a density of 7.53 g/cm³ (0.272 lb/in³), lighter than 99% of stainless steel grades. It melts at 1,425°C (2,597 °F).
Mechanical17
CB30-HT has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 62% of stainless steel grades. Elongation at break is 15% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
CB30-HT is rated for continuous service to 400°C (752 °F). It conducts heat at 23 W/m·K (13.3 BTU/hr·ft·°F), better than 78% of stainless steel grades. Thermal expansion is 10.4 µm/m·K (5.78 µin/in·°F).
Electrical3
CB30-HT conducts electricity at 2.5 % IACS, better than 75% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of CB30-HT takes about 53 MJ of energy and emits 3.6 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 75%.
Manufacturability8
CB30-HT's machinability is fair (42/100, better than 79% of stainless steel grades); weldability poor (30/100); formability not recommended (10/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CB30-HT
Is CB30 easy to machine?
Machine in the annealed condition with rigid setups, sharp carbide tooling, low speed/high feed and flood coolant; hard carbides cause abrasive tool wear.
Can CB30 be welded?
Weldable with 309/310 austenitic or matching Cr filler, but requires 200–300 °C preheat, low heat input and a post-weld anneal at ~790 °C to avoid brittle grain-boundary structure.
Can CB30 be formed, bent or molded?
Casting-only alloy — good fluidity but high shrinkage; use generous risers, controlled pour temperature and slow cooling to prevent hot tearing; no cold forming.
What surface finishes work on CB30?
Passivate in nitric acid (ASTM A967) after machining; can be shot blasted, ground and buffed, but cast carbides limit mirror polish; no anodizing.
CB30 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 |
|---|---|---|
| Cmax per ASTM A743 | ≤ 0.3 | 0.25 |
| Mn | ≤ 1 | 0.7 |
| Si | ≤ 1.5 | 1 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Crsome editions list 18–21 | 18 – 22 | 20 |
| Ni | ≤ 2 | 1 |
| Moresidual, not intentionally added | ≤ 0.5 | — |
| Fe | balance | — |
CB30-HT — frequently asked
What is CB30-HT used for?
CB30-HT is typically used for valve bodies, pump casings, nitric acid service fittings and chemical process equipment. In short: nitric-acid cast stainless; stronger than CA-type grades; casting-only alloy.
What is the yield strength of CB30-HT?
CB30-HT has a typical yield strength of 415 MPa (60.2 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 62% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is CB30-HT easy to machine?
Not especially — machinability is rated fair (42/100, better than 79% of stainless steel grades). Machine in the annealed condition with rigid setups, sharp carbide tooling, low speed/high feed and flood coolant; hard carbides cause abrasive tool wear.
Can CB30-HT be welded?
Not readily — weldability is rated poor (30/100). Weldable with 309/310 austenitic or matching Cr filler, but requires 200–300 °C preheat, low heat input and a post-weld anneal at ~790 °C to avoid brittle grain-boundary structure.
What surface finishes work on CB30-HT?
Passivate in nitric acid (ASTM A967) after machining; can be shot blasted, ground and buffed, but cast carbides limit mirror polish; no anodizing.
Can CB30-HT be formed, bent or molded?
Casting-only alloy — good fluidity but high shrinkage; use generous risers, controlled pour temperature and slow cooling to prevent hot tearing; no cold forming.
What is the maximum service temperature of CB30-HT?
CB30-HT 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 CB30-HT and CB30-F?
HT is the default condition — standard supply condition for A743 CB-30 castings: best combination of corrosion resistance and machinability. F: only for non-critical, non-corrosive duty; grain-boundary carbides lower ductility and corrosion resistance, so A743 does not accept it for service. Yield strength is 415 MPa in HT versus 400 MPa in F.
Sources
- ASTM A743/A743M — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application — ASTM International (2019)
- ASM Handbook Vol.1 — Cast Stainless Steels (ACI grades) — ASM International (1990)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- Steel Castings Handbook, 6th ed. (SFSA) — Steel Founders' Society of America (1995)
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.