Shanghai Yue Shi Welding Technology Co., Ltd.

In arc stud welding, the welding time and current decay curve settings for studs of different thicknesses/materials must adhere to the "energy matching" principle, ensuring that the heat input matches the material melting and weld bead formation requirements. The following is the specific calculation and setting method:

I. Core Calculation Logic

1. Hot Input Formula
   Total Heat Input$Q=\eta \cdot {\int }_0^{t}I(t{)}^2\cdot R(t)dt$

• ηThermal efficiency coefficient (typically ranging from 0.7 to 0.9)

• I(t)Instantaneous Welding Current (including decay curve)

• R(t)Arc Resistance (related to material and temperature)

• tWelding Time

• dBolt diameter

• λMaterial thermal conductivity (Aluminum alloy ≈ 150 W/m·K, Stainless steel ≈ 16 W/m·K)

Material/Thickness Parameter Setting Strategy

Tiny screw studs (<10mm)

• Stainless Steel (such as 316L)

• Welding Time: 0.8-1.2 seconds (requires pulse current)

• Current Attenuation: Initial Current = 1.5 times the base value, Attenuation Rate = 50A/ms

• Reason: The component must rapidly establish a molten pool; rapid attenuation can easily lead to incomplete fusion.

• Aluminum Alloy (e.g., 6061)

• Welding Time: 0.6-0.8s

• Current Decay: Initial Current = 2 times the base value, decay rate = 80A/ms

• Reason: High thermal conductivity requires "high energy density plus short duration."

2. Heavy Hex Bolts (>20mm)

• Carbon Steel (e.g., Q345)

• Welding Time: 2.0-3.0 seconds (Segmented control: Preheat 1.0 second + Welding 2.0 seconds)

• Current Attenuation: Preheat Segment Attenuation Rate = 20A/ms, Welding Segment = 40A/ms

• Reason: Segmented control to prevent the melt pool from overheating.

• Titanium alloy (such as TC4)

• Welding Time: 1.5-2.0 seconds

• Current Attenuation: Initial Current = 1.2 Times Base Value, Attenuation Rate = 30A/ms

• Reason: Titanium alloy has a high melting point (1668°C), requiring an extended duration of high-temperature residence.

Section III: Dynamic Parameter Adjustment Method

1. Splash Control

• When the spatter rate exceeds 5%, reduce the current decay rate (ΔI/Δt↓) or shorten the welding time.

• By X-ray inspecting the melt depth standard deviation, if σ > 0.3mm, adjust the current waveform to "double-peak" mode (pre-pulse + main pulse).

• For materials with quenching tendency (such as martensitic stainless steel), employ a "high at the beginning, low at the end" decay curve to reduce high-temperature dwell time.

Section IV: Engineering Practice Recommendations

1. Bolt diameter compatibility

• Welding time is proportional to the square of the bolt diameter.$t\propto d^2$No Chinese content provided.

• In low-temperature environments (below 10℃), the welding time is extended by 10%-15% to compensate for heat loss.

• When the current decay rate of a standard power supply is less than <100A/ms, prioritize controlling heat input by adjusting the welding time.

By integrating numerical simulations (such as COMSOL thermal field simulation) and process experiments (optimized using the orthogonal method), further refined parameter control can be achieved. In practical applications, it is recommended to establish a material-thickness-parameters database, quickly set initial parameters through lookup tables, and then fine-tune based on the initial inspection results.