Steel casting components, particularly pump casings, face significant challenges in balancing quality and manufacturing costs. This study focuses on optimizing the casting process for single-suction pump casings made of dual-phase steel, aiming to improve yield rates while maintaining defect-free production. Traditional methods for steel casting pump casings exhibit low process yields (<50%), primarily due to shrinkage and inclusion defects, which increase material waste and reduce competitiveness.
Defect Analysis in Steel Casting
Defects in steel casting pump casings are categorized into two types:
| Defect Type | Cause | Critical Locations |
|---|---|---|
| Shrinkage | Insufficient feeding during solidification | Seal ring, inlet flange, connection flange |
| Inclusions | Slag entrapment or refractory erosion | Flow passage regions |
For dual-phase steel casting, the following material characteristics demand specific process considerations:
$$
\begin{cases}
\text{High melting point} \\
\text{Low fluidity} \\
\text{High shrinkage (2.0–2.5\%)} \\
\text{Oxidation sensitivity}
\end{cases}
$$
Gating System Design for Steel Casting Optimization
A bottom-gated open system was designed to address turbulence and temperature gradients. Key parameters include:
- Pouring temperature: 1,580°C
- Pouring time:
$$
t = \sqrt[2]{W} + \sqrt[3]{W} \approx 27.4 \, \text{s} \quad (W = 400 \, \text{kg})
$$ - Gating ratio:
$$
A_{\text{choke}} : A_{\text{runner}} : A_{\text{ingate}} = 1 : 1.1 : 1.2
$$
| Parameter | Original Process | Optimized Process |
|---|---|---|
| Yield Rate | 47% | 68% |
| Risers per Casting | 5 | 3 |
| Material Cost Reduction | — | 44% |
Simulation-Driven Process Validation
MAGMA simulations compared two orientations for steel casting solidification:
- Connection flange upward: Required extensive risers to feed shrinkage-prone zones.
- Connection flange downward: Concentrated defects at critical junctions, enabling localized feeding solutions.
The final design incorporated chromite sand inserts to balance modulus:
$$
M_{\text{critical}} = \frac{V}{A} \approx 0.8 \, \text{cm}
$$
where \( V \) is volume and \( A \) is cooling surface area.
Production Results in Steel Casting
Post-optimization trials demonstrated:
- Zero leakage failures in 1.5 MPa pressure tests
- 62% reduction in grinding labor
- 3-hour reduction in machining time per unit
This steel casting process innovation highlights the effectiveness of simulation-guided design in resolving contradictory requirements between feeding efficiency and defect prevention. The methodology provides a replicable framework for complex steel casting components requiring high structural integrity and cost efficiency.