Preheat Treatment Aisi 5140 Steel Pipes Before Welding - China

AISI 5140 steel pipes are medium-carbon alloy structural steels (carbon content 0.38%-0.43%, Cr content, the primary alloying element, 0.70%-0.90%).

Their weldability is moderate.

Due to their high carbon equivalent, they are highly susceptible to cold cracking during welding, and the weld zone is prone to the formation of a hardened structure (martensite), resulting in reduced toughness.

Therefore, preheating before welding is a key process step to ensure weld quality, requiring strict control of the preheating temperature, range, heating rate, and holding time.

Preheating Preparation

Surface Cleaning: Remove impurities such as oil, rust, and scale within a 20mm radius on both sides of the welded joint (using a wire brush, sandpaper, or sandblasting is recommended).

This prevents impurities from burning during preheating and creating pores, which could affect temperature uniformity.

Joint Positioning: Ensure that the gap and misalignment of the AISI 5140 steel pipes meet the welding process requirements (e.g., gap 2-4mm, misalignment ≤10% of the wall thickness) to avoid rework after preheating due to joint misalignment.

Temperature Measurement Tool Calibration: Use a contact thermocouple (K-type recommended) or infrared thermometer (accuracy ±5°C).

Calibrate the equipment in advance to ensure accurate temperature readings.

(Infrared thermometers should avoid measuring areas with scale or oil to prevent data deviation).

In summary, the key to preheating AISI 5140 steel pipes before welding is "**precise temperature control, uniform heating, and timely connection**.

" Parameters must be optimized based on actual working conditions, and rigorous process monitoring and documentation must be implemented to ensure that the welded joint quality meets mechanical properties and service requirements.

Company Contact:

• Posted By: Dongguan Songshun Mould Steel Co., Ltd.

• Phone: 076985475596

• Address: 1st Floor, No. 1, Dongda Fourth Street, Shatou Community, Chang'an Town, Dongguan , Guangdong , China

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• Website: https://songshunsteel.com/

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