Which grade of cast iron is best for heavy-duty 3D welding tables?

For heavy‑duty 3D welding tables, the best cast iron grades are high‑strength grey cast iron HT300 (G250 / Class 250) and ductile iron QT600‑3 (65‑45‑12). HT300 is the industry standard for most heavy‑duty applications.

1. High‑Strength Grey Cast Iron (Most Widely Used)

Grade: HT300 (China) / G250 / Class 250 (International)

Tensile strength: ≥ 300 MPa

Hardness: 190–240 HB

Key advantages for heavy‑duty 3D welding tables:

Excellent rigidity and load capacity, supporting heavy workpieces with minimal deflection.

Superior damping, absorbing welding vibration far better than steel, critical for precision 3D fixturing.

Outstanding thermal stability, resisting warping from repeated welding heat.

Good wear resistance, resisting denting and weld spatter adhesion.

Cost‑effective, balancing performance and cost better than ductile iron for most welding shops.

Typical use: Standard heavy‑duty 3D welding tables, automotive, heavy machinery, structural steel welding.

2. Ductile (Nodular) Cast Iron (For Extreme Heavy‑Duty)

Grade: QT600‑3 (China) / 65‑45‑12 (International)

Tensile strength: ≥ 600 MPa

Elongation: 3% (far higher than grey iron)

Key advantages:

Higher strength and toughness, with better impact resistance for extremely heavy or shock‑prone welding.

Strong fatigue resistance, providing longer service life under cyclic heavy loads.

Trade‑offs:

Slightly lower damping than HT300.

Higher cost and more difficult to machine.

Typical use: Ultra‑heavy‑duty 3D tables for shipbuilding, mining equipment, large pressure vessels.

3. HT250 (Mid‑Range Heavy‑Duty)

Tensile strength: ≥ 250 MPa

Hardness: 180–220 HB

Suitable for moderate‑heavy 3D welding tables, common as a cost‑effective alternative to HT300 for general industrial use.

Selection Summary

Standard heavy‑duty use is best with HT300 (G250). For ultra‑heavy loads and high impact, choose QT600‑3 (65‑45‑12). For moderate‑heavy and cost‑sensitive projects, HT250 is a practical choice.

Critical Notes for Performance

Stress relief is mandatory. Tables must undergo artificial aging (600–700°C annealing) or long natural aging to eliminate internal stress and ensure long‑term dimensional stability. Plasma nitriding is highly recommended for surface treatment to improve hardness, spatter resistance, and corrosion protection.

Final Recommendation: For nearly all heavy‑duty 3D welding table applications, HT300 (Class 250 grey cast iron) is the best choice, offering the ideal balance of rigidity, damping, thermal stability, wear resistance, and cost. For extreme loads and impacts, upgrade to QT600‑3 ductile iron.

GB/T 7714:Caffrey C,Bolon K,Kolwich G,et al.Cost-effectiveness of alightweight design for 2020-2025:an assessment of a light-duty pickup truck[R].SAE Technical Paper,2015.

MLA:Caffrey,Cheryl,et al.Cost-effectiveness of a lightweightdesign for 2020-2025:an assessment of a light-duty pickuptruck.No.2015-01-0559.SAE Technical Paper,2015.

APA:Caffrey,C.,Bolon,K.,Kolwich,G.,Johnston,R.,&Shaw,T.(2015).Cost-effectiveness of a lightweight design for 2020-2025:an assessment of a light-duty pickup truck(No.2015-01-0559).SAE Technical Paper.