TIG Settings: Expert Guide for Steel, Stainless Steel and Aluminium

Amperage: the driving force behind fusion

Amperage is the concentrated heat source required to create the weld pool. It must be set in proportion to the workpiece thickness and the thermal conductivity of the material to ensure proper penetration without burn-through.

Controlling steel and stainless steel with direct current (DC)

When welding steel, direct current electrode negative (DCEN) polarity is used. This configuration helps protect the electrode by directing only 30% of the heat toward it, while approximately 70% is concentrated in the workpiece. The current must be adjusted precisely: insufficient amperage can cause poor fusion, while excessive current may lead to root-side oxidation. Using a DC TIG welding machine or a professional model such as the Picotig 180 puls DC allows precise control of the heat input.

Specific requirements for aluminum with alternating current (AC)

Aluminum requires higher amperage to compensate for its high thermal conductivity. Alternating current (AC) is required to break down the aluminum oxide layer. Modern inverter machines use square-wave technology to transition almost instantaneously through the zero-current point, helping stabilize the arc and optimize energy transfer despite the metal's high thermal conductivity.

The stability of the arc must then be maintained through pulse settings and shielding gas protection free from excessive turbulence.

Pulse and shielding gas flow: protection and heat control

These parameters protect the tungsten electrode and isolate the weld pool from atmospheric contamination, which can cause porosity.

Optimizing Pulse mode

Pulse mode alternates between peak current, which produces fusion, and background current, which allows the weld pool to cool. By adjusting the duty cycle and pulse frequency, the welder can reduce the Heat-Affected Zone (HAZ), thereby limiting distortion on thin sheet metal. For consistent weld quality, using a TIG filler rod suited to these thermal cycles is essential.

Critical management of gas flow and supply lines

Effective shielding requires precise gas-flow management:

• Pre-flow: Minimum 0.2 s to purge the torch before the arc is initiated.
• Post-flow: Amperage / 10 = time in seconds (minimum 8 s). Keep the torch positioned above the weld pool until the gas flow stops.
• Laminar flow: Prefer a converging nozzle to maintain laminar gas flow for as long as possible. Never use green oxygen hoses for shielding gas, as they can significantly increase the risk of contamination. A flow rate of 5 to 16.5 L/min, controlled using accurate gas regulators, helps maintain weld-pool purity.

Advanced AC settings for aluminum

Modern inverter machines make it possible to manage the aluminum oxide layer, which melts at around 2,000°C, without excessively melting the underlying aluminum, which has a melting point of approximately 660°C.

AC balance: cleaning vs. penetration

The AC balance setting determines the ratio between electrode negative (%EN) and electrode positive (%EP).

• EP provides the cleaning action: during the electrode-positive portion of the cycle, the arc helps break down and remove the oxide layer from the surface.
• EN provides penetration: It concentrates heat in the base metal. On a TIG AC/DC welding machine, a setting of approximately 75% EN is a common starting point. An AC balance with too much EP, such as 50/50, can cause excessive rounding of the tungsten electrode and an unnecessarily wide weld bead.

AC frequency and correcting black “pepper” contamination

AC frequency (Hz) influences the width and directional focus of the arc cone. At 200 Hz, on equipment such as the Tetrix XQ Pulse 230 AC/DC, the arc becomes extremely narrow and directional, making it particularly suitable for precise root passes. If black contaminants or “pepper” appear in the weld pool, reduce the %EN to increase the EP cleaning action while also improving mechanical surface preparation before welding.

Summary of settings and test methodology

Meeting industrial welding requirements means testing each parameter configuration on a test coupon before welding the final workpiece.

Key takeaway

TIG settings work as an interconnected system: amperage controls fusion, shielding gas protects the chemical environment through controlled laminar flow, while AC balance and frequency shape the weld bead and penetration profile. Compliance with the Welding Procedure Specification (WPS) and the welding machine manufacturer's instructions should always take precedence.

Recommended next step

Systematically check the condition of your TIG accessories. Use rare-earth-alloyed tungsten electrodes such as 2% Ceriated (Grey) or 1.5–2% Lanthanated (Gold, Blue or Black). Avoid Pure Tungsten (Green) with modern inverter machines, as it tends to ball excessively and may result in arc instability. Grind the electrode to a truncated point to improve heat resistance and arc stability.