Welding Process Control

1. Heat Input Control

Principle: Adopt moderate-to-low heat input (typically ≤20 kJ/cm) to prevent grain coarsening in the weld and heat-affected zone (HAZ), which can degrade impact toughness.

Formula:\(\text{Heat Input (kJ/cm)} = \frac{\text{Current (A)} \times \text{Voltage (V)}}{\text{Welding Speed (cm/s)}}\) Example: If current = 200 A, voltage = 24 V, and welding speed = 5 mm/s (0.5 cm/s):\(\text{Heat Input} = \frac{200 \times 24}{0.5} = 9600 \, \text{J/cm} = 9.6 \, \text{kJ/cm}\)

2. Number of Layers/Passes and Interpass Cooling

Multi-Layer/Multi-Pass Welding:

Avoid single-pass welding to prevent microstructure deterioration due to excessive heat input.

Layer thickness: ≤4–5 mm per layer.

Pass width: ≤4× electrode diameter (for SMAW) or ≤2.5× wire diameter (for GMAW).

Interpass Temperature Control:

Maintain interpass temperature ≤250°C (to avoid austenite transforming into coarse structures) and ≥ preheating temperature minimum.

Use temperature measurement (e.g., infrared thermometers) or forced cooling (air/water) to regulate cooling rates.

 

 

 

High strength steel plate Q420B

Product Name	High strength steel plate Q420B 16Mo3 16MnL 16MnR high tensile steel plate/sheet
Length	4m-12m or as required
Width	0.6m-3m or as required
Thickness	3mm-300mm or as required
Standard	AISI,ASTM,DIN,JIS,GB,JIS,SUS,EN,etc.
Technique	Hot rolled
Surface Treatment	Clean, blasting and painting according to customer requirement
Thickness tolerance	±0.1mm
Material	Q345B,Q345C,Q345D,Q345E,Q390,Q390B,Q390C,Q390D,Q390E,Q420,Q420B, Q420C,Q420DQ420E,Q460,Q460D,Q500C,Q500D,Q500E,Q550C,Q550D,Q550E, Q620C,Q620D,Q620E,Q690A,Q690B,Q690C,Q690D,Q690E,Q690D,Q690C,Q890C,Q890D 16Mo3,16MnL,16MnR ,16Mng,16MnDR HG785D,S690QL,50MN

 

 

 

3. Operational Key Points

Electrode/Wire Angle: Maintain a 60–80° angle with the weld groove to avoid arc blow and incomplete fusion.

Oscillation Amplitude:

For GMAW: Limit oscillation to prevent shielding gas disruption.

For SMAW: Allow moderate transverse oscillation to ensure fusion at the groove sides.

Crater Filling: Fill the weld crater completely to avoid shrinkage porosity and cracks. Use current decay or multiple arc extinction techniques.

 

 

 

 

 

 

 

 

 

 

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All staff of our company and all departments work together to combine business management, professional technology, quantitative statistical methods and ideological education.
Our Cold-rolled Steel products are known for their durability and reliability.
Relying on the superior conditions and strong advantages of mass production, we are able to meet the different needs of our customers.

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