This study presents a comprehensive analysis of steel casting process optimization for mining flatcar wheels using numerical simulation techniques. The ZG50Mn2 steel casting, with critical dimensions of 353 mm × 403 mm × 152 mm and mass of 59.2 kg, requires exceptional mechanical properties to withstand cyclic stresses in mining operations. Through systematic process improvement, we successfully eliminated shrinkage defects and improved casting quality.
1. Thermal Properties and Phase Analysis
The chemical composition and mechanical properties of ZG50Mn2 steel are summarized in Table 1. The phase diagram analysis reveals critical temperature parameters for casting process design:
$$T_{liquidus} = 1,484°C$$
$$T_{solidus} = 1,397°C$$
| Element | C | Mn | Si | P | S |
|---|---|---|---|---|---|
| Content (wt%) | 0.45-0.55 | 1.50-1.80 | 0.20-0.40 | ≤0.030 | ≤0.030 |
2. Numerical Simulation of Steel Casting Process
ProCAST simulations revealed critical solidification characteristics in the initial casting design:
$$Q = h \cdot A \cdot (T_{casting} – T_{mold})$$
Where:
Q = Heat transfer rate (W)
h = Heat transfer coefficient (500 W/m²K)
A = Interface area
The initial gating system showed significant shrinkage defects (146.96 cm³ total volume) due to improper solidification sequence. Thermal analysis identified problematic regions through temperature gradient mapping:
| Solidification Stage | Critical Observation |
|---|---|
| 30% Solidified | Thermal gradient: 85°C/cm |
| 70% Solidified | Isolated liquid pockets formation |
3. Process Optimization Strategy
Key improvements for steel casting quality enhancement included:
3.1 Riser Design
Modulus calculations ensured proper feeding:
$$M_{casting} = \frac{V}{A} = 1.173$$
$$M_{riser} = 1.55 \geq 1.2M_{casting}$$
3.2 Chilling System
High-carbon steel chills (thermal conductivity: 45 W/mK) accelerated local cooling:
| Parameter | Value |
|---|---|
| Chill-casting HTC | 2,000 W/m²K |
| Chill-sand HTC | 500 W/m²K |
4. Optimized Steel Casting Results
The modified system achieved directional solidification with complete shrinkage elimination. Solidification sequence monitoring showed:
$$t_{riser\_solidification} = 1.21t_{casting\_solidification}$$
| Parameter | Initial | Optimized |
|---|---|---|
| Shrinkage Volume | 146.96 cm³ | 0 cm³ |
| Yield Improvement | 72% | 89% |
5. Mechanical Performance Validation
The optimized steel casting met all industrial requirements:
$$UTS = 785\ MPa$$
$$YS = 445\ MPa$$
$$\varepsilon = 18\%$$
This comprehensive approach demonstrates how numerical simulation combined with strategic process modifications can significantly improve steel casting quality in heavy industrial applications. The methodology provides a reliable framework for optimizing complex steel castings while maintaining cost-effectiveness in production.