Key points and difficulties in the welding process of high strength steel

At present, China's construction steel structure industry has gradually transitioned from a developmental phase to a mature stage. The country leads globally in both steel production and consumption. In many steel structure projects, high-strength steel with thick sections is increasingly being used to meet the demands of complex architectural designs and structural load requirements. **Key Challenges and Difficulties in Welding High-Strength Steel:** 1. According to international standards, weldability testing for new steel grades should be conducted by manufacturers and research institutions. However, in China, there is no clear regulation on this, and it is often carried out by the construction company. This lack of standardization makes the weldability test of new steel grades a major challenge in steel structure engineering. 2. As the amount of alloying elements increases in the steel, it can significantly affect the hardening, softening, and cracking tendencies of the welded joint. Therefore, preventing welding cracks and embrittlement in the heat-affected zone becomes a critical issue during the welding process of high-strength steel. 3. Preventing layer tearing in thick-walled high-strength steel during welding is another key challenge. Proper control is essential to ensure the integrity and safety of the welded joints. 4. The design of the groove for slab high-strength steel directly impacts the construction timeline and the internal quality of the weld. Therefore, optimizing the groove design is a central concern in the welding process. **Main Technical Measures Taken to Address These Challenges:** (1) Selecting appropriate welding materials that match the base metal is crucial. Low-hydrogen and ultra-low-hydrogen welding consumables are recommended to minimize defects like cracks and porosity. For specific guidelines, refer to GB8110—2008 for carbon steel gas-shielded arc welding and GB/T5293 for submerged arc welding wire and flux. (2) Groove design plays a vital role in thick plate welding. A narrow and deep groove may lead to poor weld formation, regional segregation, and hot cracking under high stress. On the other hand, a wide groove increases welding volume and residual stress, which is not ideal for controlling initial stress in the steel structure. Therefore, a 30°–35° groove angle is typically used, with a gap of 6–10 mm. When the plate thickness exceeds 40 mm, a layered tearing groove is required. Bevel processing should be done using a flame cutting machine to avoid manual cutting, which could compromise welding quality. (3) To prevent welding cracks, preheating the weld area and its surrounding 100 mm is essential. The preheating temperature should follow the guidelines in GB50661 "Code for Welding of Steel Structures." During the welding process, the interlayer temperature must be strictly controlled, and it should not fall below the preheating temperature. Using small current helps reduce heat input, thus minimizing deformation and stress. Multi-layer multi-pass welding should be avoided. After welding, post-heating and hydrogen removal treatments are necessary to allow residual hydrogen to escape, reducing the risk of cold cracking. For more detailed information, please refer to the attached content or consult the 18th issue of *Metalworking (Hot Processing)*.

Rotary Rings

Rotary Rings are a type of rotating seal widely used in various rotating equipment, such as rotary joints, rotary couplings, rotary connectors, etc. Its main function is to prevent liquid or gas leakage and maintain the normal operation of the equipment. In different applications, the material, structure, sealing method, size, etc. of Rotary Rings vary to adapt to different working conditions.

1. Material classification

The materials of Rotary Rings are mainly divided into two categories: metallic and non-metallic.

1. Metal materials

Metal materials mainly include stainless steel, steel, copper, aluminum, etc., which have characteristics of high strength, corrosion resistance, wear resistance, and are suitable for rotary seals in harsh environments such as high temperature, high pressure, and high-speed.

2. Non metallic materials

Non metallic materials mainly include ceramics, silicon carbide, graphite, etc., which have characteristics such as high hardness, high wear resistance, and low friction coefficient. They are suitable for rotary seals under conditions such as low temperature, low pressure, and high speed.

2. Structural classification
The structure of Rotary Rings is mainly divided into three types: unidirectional rotation, bidirectional rotation, and rotational stationary.
1. Unidirectional rotating structure

The Rotary Rings with a unidirectional rotation structure can only rotate in one direction and are suitable for devices with only unidirectional rotation.

2. Bidirectional rotation structure

The Rotary Rings with a bidirectional rotation structure can rotate in two directions, suitable for devices that require bidirectional rotation.

3. Rotating stationary structure

The Rotary Rings with a rotating stationary structure are composed of a rotating ring and a stationary ring. The rotating ring contacts the stationary ring during rotation to achieve sealing, suitable for equipment that requires a rotating stationary seal.

3. Classification of sealing methods

The sealing methods of Rotary Rings are mainly divided into mechanical sealing and liquid sealing.

1. Mechanical seal

Mechanical sealing is achieved through the contact surface between the rotating ring and the stationary ring, which has the characteristics of high reliability, long service life, and simple maintenance. It is suitable for rotary sealing in harsh environments such as high speed, high temperature, and high pressure.

2. Liquid sealing

Liquid sealing is achieved by injecting liquid between the rotating ring and the stationary ring, which has the characteristics of good sealing performance, low friction coefficient, and preventing dry friction. It is suitable for rotary sealing under low speed, low temperature, low pressure, and other conditions.

4. Size classification

The size of Rotary Rings is mainly determined by the equipment requirements, including inner diameter, outer diameter, thickness, shaft diameter, etc.

Rotary Rings, as an important type of rotary seal, are widely used, with different materials, structures, sealing methods, dimensions, etc. to adapt to different working conditions. When selecting Rotary Rings, it is necessary to make the selection based on specific equipment requirements to ensure the normal operation of the equipment.

Rotary Seals,Rotary Lip Seal,Rotating Shaft Seal,V Seals

DG Zhongxingshun Sealing Products Factory , https://www.zxs-seal.com