According to the location of defects, steel welding defects can be divided into external defects and internal defects. External defects refer to defects that appear on the surface or edge of the weld seam, such as cracks, pores, splashes, undercuts, pits, overlaps, etc. Internal defects refer to defects that occur inside the weld seam or heat affected zone, such as incomplete fusion, slag inclusion, incomplete penetration, necklace cracks, etc.

I. Reasons for Welding Defects in Steel

The main reasons for steel welding defects are as follows:

The welding process is unreasonable. For example, selecting unsuitable welding methods, current, voltage, speed, polarity, etc. can lead to issues such as unstable arc, difficulty in controlling the melt pool, and excessive or insufficient heat input.

Welding operations are not standardized. For example, uneven electrode oscillation, improper arc length, long or short dwell time, insufficient or excessive addition of filler metal, etc., can affect weld formation and metal flow.

The welding material is not qualified. For example, impurities or gases in the base material or filler material, oil or rust on the surface, poor electrode quality or improper storage can cause contamination or gas generation in the welding area.

Poor welding environment. For example, high or low temperature, high or low humidity, fast or slow wind speed, etc. can affect the stability of the arc and the effectiveness of the protective gas.

II Remedial Measures for Welding Defects in Steel

The remedial measures for steel welding defects mainly include the following:

Use non-destructive testing methods to inspect the quality of welds, such as ultrasonic testing, radiographic testing, eddy current testing, etc. If defects beyond the standard range are found, they should be repaired or replaced in a timely manner.

Adopting reasonable preheating and post heat treatment methods to improve welding stress and microstructure. For example, for materials prone to cracking such as high carbon steel and low alloy steel, appropriate preheating should be carried out before welding, and appropriate post heat treatment should be carried out after welding.

Use correct welding process parameters and operating specifications to control arc characteristics and melt pool behavior. For example, based on the properties of the base material and filler material, appropriate welding methods, current, voltage, speed, polarity, etc. are selected to maintain stable arc, uniform melt pool, and moderate heat input.

Using high-quality welding materials and clean welding surfaces to reduce pollution and gas generation. For example, selecting base materials and filler materials that meet standards, avoiding the use of materials containing impurities or gases, using qualified electrodes, and storing them properly. For surfaces with oil stains or rust, cleaning or polishing should be carried out.

 III. Summary

Welding defects in steel are important factors that affect welding quality and strength, and should be given sufficient attention. By understanding the types, causes, and remedial measures of steel welding defects, it is possible to effectively prevent and solve welding defects, improve welding efficiency and reliability. This article provides you with some basic knowledge and suggestions, hoping to be helpful to you.