Research on Welding Process of Steel Casting and High-Strength Wear-Resistant Steel Plate

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This study investigates the weldability between K360 high-strength wear-resistant steel and ZG30MnSi low-alloy cast steel, focusing on cold cracking sensitivity and mechanical property optimization. As critical materials in mining/engineering machinery, both steels exhibit distinct challenges in welding due to their composition and casting characteristics.

1. Material Composition and Properties

The chemical compositions and mechanical properties of base metals are summarized in Tables 1-2. ZG30MnSi cast steel demonstrates typical steel casting characteristics with higher carbon content (0.30%) compared to K360 (0.15%), influencing their respective welding behaviors.

Table 1: Chemical Composition (wt%)
Material C Si Mn Cr Ti B
K360 0.15 0.22 0.96 0.61 0.012 0.001
ZG30MnSi 0.30 0.72 1.08 – – –
Table 2: Mechanical Properties
Material Yield Strength (MPa) Tensile Strength (MPa) Elongation (%)
K360 1083 1246 20.8
ZG30MnSi 430 620 14

2. Cold Cracking Sensitivity Analysis

The cold cracking tendency was evaluated using IIW formulas:

Carbon equivalent (CE):

$$ CE = C + \frac{Mn}{6} + \frac{Cr + Mo + V}{5} $$

Cracking susceptibility index (Pc):

$$ P_c = C + \frac{Si}{30} + \frac{Mn}{20} + \frac{\delta}{600} + \frac{H}{60} $$

Minimum preheat temperature (T0):

$$ T_0 = 1440P_c – 392 $$

Table 3: Calculated Welding Parameters
Material CE (%) Pc (%) T0 (°C)
K360 0.43 0.28 11.2
ZG30MnSi 0.48 0.43 227

3. Welding Process Optimization

Using CHW-50C8 wire (Ø1.2mm) with 80%Ar+20%CO2 shielding gas, we conducted bead-on-plate tests with varied heat inputs:

Table 4: Welding Parameters
Current (A) Voltage (V) Speed (mm/min) Heat Input (kJ/mm)
240 26 450 0.832
280 30 400 1.260
320 33 350 1.810

The steel casting component (ZG30MnSi) showed distinct responses to thermal cycles:

$$ \Delta T = \frac{q}{v} \cdot \frac{1}{\rho c \sqrt{\pi \alpha t}} $$

Where q = arc energy, v = welding speed, ρ = density, c = specific heat, α = thermal diffusivity.

4. Mechanical Property Analysis

Table 5 demonstrates how steel casting properties interact with welding parameters:

Table 5: Mechanical Properties vs Heat Input
Heat Input (kJ/mm) UTS (MPa) Impact Energy (J)
0.832 682 126
1.260 640 123
1.810 624 101

5. Process Recommendations

For optimal steel casting-weldment integration:

  1. Preheat temperature: 100-150°C
  2. Interpass temperature: 100-200°C
  3. Heat input range: 0.8-1.8 kJ/mm
  4. Gas protection: 20 L/min

This comprehensive approach ensures reliable welding between cast steel components and high-strength plates, crucial for heavy machinery applications requiring superior wear resistance and structural integrity.

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