Overview of HUABAO metal Welding-Stress Relief Method

I. Overview

       HUABAO stress relief method is a popular post-welding treatment, surface local strengthening, and residual stress elimination method abroad. This method was first born in the former Soviet Union and rapidly developed in the United States in the 1960s. It was recognized as the most effective method to improve the fatigue performance of welded structures at the 13th International Welding Institute and rapidly promoted and applied in developed countries. After more than half a century of development, the process and equipment for Hawking energy stress relief have become increasingly sophisticated. The actuator of this method is lightweight, flexible and convenient to use, with low noise, high efficiency, low cost, energy saving, and no pollution.

The HB series HUABAO energy stress relief device, as a post-welding treatment equipment, can simultaneously improve multiple factors affecting weld quality, such as stress, defects, weld toe geometry, and surface strengthening. Therefore, it has a multiplier effect on improving the fatigue performance of welded joints, which can increase the fatigue strength of the treated welded joints by 50%-120% and extend the fatigue life by 5-100 times. As a result of using the Hawking stress relief method, traditional grinding and slag removal processes are eliminated, saving 20% of labor time, reducing labor intensity, and improving production efficiency.

At the same time, this method is also widely used in the following three aspects: (1) strengthening the surface of metal parts to improve their surface quality and fatigue life; (2) adjusting the stress field, reducing existing welding deformation, and ensuring dimensional stability of the workpiece; (3) eliminating welding stress in locally welded repair areas of mechanical parts. This method is now commonly used in foreign machinery manufacturing projects, especially in welded structures with high fatigue performance requirements.

II. Effects of HUABAO Stress Relief Method

1. It can increase the fatigue strength of welded joints by 50%-120% and extend the fatigue life by 5-100 times.

2. It is the most thorough process method to eliminate residual tensile stress and generate ideal compressive stress.

3. It effectively improves the geometric shape of the weld toe, reduces stress concentration at the weld toe and the weld seam, and has a simple process with low cost.

4. It eliminates microcracks and slag defects on the surface of the weld toe, inhibiting the premature initiation of cracks.

5. It changes the original stress field and significantly reduces welding deformation.

6. Local strengthening treatment improves the surface quality and fatigue life of parts.

7. It eliminates welding stress and strengthens locally welded repair areas of mechanical parts.

8. It improves the corrosion resistance of metals in corrosive environments by about 400%.

9. It simultaneously improves several factors affecting the fatigue performance of weld seam: weld toe geometry, residual stress, microcracks and slag defects, surface strengthening, etc., thus significantly improving the fatigue strength and fatigue life of welded joints.

III. Advantages of HUABAO Stress Relief Method Compared to Traditional Fatigue Performance Improvement Processes

1. HUABAO stress relief treatment can simultaneously improve several factors affecting the fatigue performance of welds, such as residual stress, microcracks and defects, weld toe geometry, and surface strengthening, thus significantly improving the fatigue performance of welds with multiplier effects.

2. In eliminating stress concentration at the weld toe, it is the most convenient and effective method, far surpassing methods such as tungsten inert gas welding remelting (TIG) or grinding at the weld toe.

3. Elimination of Welding Residual Stress

HUABAO stress relief method fully replaces heat treatment and vibration stress relief methods, providing a simple process with stable and reliable results. It offers flexibility to treat any desired area at any time and during any step of the process, allowing for convenient and effortless application. Unlike vibration stress relief, the process is uncomplicated and unaffected by numerous process parameters.

4. Replacement of Shot Peening

HUABAO stress relief method completely replaces the shot peening process for improving local fatigue life and eliminating residual stress of workpieces. This method is unparalleled, saving space and eliminating issues related to shot recovery and safety hazards, thus improving the working environment.

5. Restoration of Deformed Welded Components

Under natural conditions, Hawking stress relief method effectively restores deformed welded components to their original state, serving as a convenient tool for calibration.

6. Flexibility of Application

HUABAO stress relief requires minimal space and is not limited by the material, shape, structure, or weight of workpieces, offering flexible and convenient use.

7. Environmental Friendliness

The method is environmentally friendly, energy-efficient, safe, and pollution-free.

IV. Application Areas of  HUABAO Stress Relief Method

HUABAO stress relief method is widely used in the manufacturing of welded structures in industries such as shipbuilding, bridge engineering, military, aerospace, power, rail, automotive, lifting equipment, oil drilling, machinery, and pressure vessels. It significantly improves the fatigue strength and fatigue life of welded joints, eliminates welding residual stress, and reduces welding deformation. It is also commonly used for residual stress elimination and strengthening of locally welded repair areas in mechanical parts. Additionally, it can be used to impact treat areas of metal parts requiring surface strengthening, significantly enhancing their fatigue strength and fatigue life. Therefore, Hawking stress relief method has broad application prospects in the manufacturing and maintenance processes of the machinery manufacturing industry, promising significant social and economic benefits.

V. Basic Principle of HUABAO Stress Relief Method

The basic principle of HUABAO stress relief method involves using high-power impact tools to strike the surface of metal objects at a frequency of over 20,000 times per second. Due to the high frequency, efficiency, and focused energy of Hawking energy, it causes significant compressive plastic deformation in the metal surface. Simultaneously, it alters the original stress field, generating a certain amount of compressive stress and strengthening the impacted area.

VI. Basic Principle of Improving Fatigue Performance of Welded Joints Using HUABAO Stress Relief Method

During welding of metal structural components, the commonly used fusion welding method often leaves excessive height, pits, and various welding defects at the joint, resulting in severe stress concentration and welding residual stress. Residual tensile stress is often detrimental to the fatigue strength of welded structures. Furthermore, research has shown that slag defects exist approximately 0.5mm from the surface of the weld toe, which are sharp and equivalent to the premature initiation of fatigue cracks. The combined effect of stress concentration, weld toe slag defects, and welding residual tensile stress significantly reduces the fatigue strength and fatigue life of welded joints.

The basic principle of improving the fatigue strength and fatigue life of welded joints using HUABAO stress relief method involves utilizing Hawking energy to drive impact tools to strike the weld toe area along the weld seam at a frequency of over 20,000 times per second. This generates significant compressive plastic deformation, creating a smooth geometric transition at the weld toe, significantly reducing stress concentration caused by excessive height and pits. It eliminates microcracks and slag defects on the surface of the weld toe, inhibiting the premature initiation of cracks. It adjusts the welding residual stress field, eliminating tensile stress and generating a certain amount of residual compressive stress near the weld toe. Additionally, it strengthens the material at the weld toe. Therefore, Hawking stress relief method can simultaneously improve several factors affecting the fatigue performance of weld seam, such as weld toe geometry, residual stress, microcracks and slag defects, and surface strengthening, significantly enhancing the fatigue strength and fatigue life of welded joints.

VII. Advantages of HUABAO Stress Relief Method Compared to Heat and Vibration Stress Relief for Residual Stress Elimination

- It fully eliminates residual stress, achieving a residual stress elimination rate over three times higher than vibration stress relief.

- Residual stress can be eliminated at any desired location, making it easy and convenient to apply.

- It does not require complex process requirements like vibration stress relief, making it simple to operate and easy to learn. It is not limited by workpiece weight, volume, shape, fixture method, natural frequency, or equipment excitation force.

-For welded components, vibration stress relief is typically performed after the completion of the workpiece, whereas Hawking stress relief method can be conveniently applied during the welding process at any time, or after the completion of the workpiece. This method also reduces the need for grinding and slag removal, saving labor time and enhancing production efficiency.

-The effectiveness of HUABAO stress relief method is highly controlled and targeted, in contrast to the unstable and less controllable outcomes of vibration stress relief.

-Not only does it eliminate residual stress, but it also significantly improves the fatigue performance of the workpiece.

-It effectively addresses welding deformations, enabling the leveling and straightening of distorted welded components.

-Compared to thermal stress relief, HUABAO stress relief method achieves energy savings of over 95%.

-It is environmentally friendly and operates without noise.

-Unlike thermal stress relief, HUABAO stress relief method does not cause surface oxidation issues.