The main energy parameters that determine the weld size are welding current, voltage and welding speed.

Preheating before welding and heat treatment after welding have great influence on welding quality. Preheating before welding is required for important components.

The main disadvantage of CO2 gas shielded welding is welding spatter, which mainly adopts the following measures:

Welding heat treatment residual stress refers to the residual stress of the workpiece after heat treatment, which has a very important impact on the shape, size and performance of the workpiece. When the material yield strength exceeds, it will cause deformation. When the strength limit of welding material exceeds, it will produce cracks, which should be reduced and eliminated.

Generally, forging cracks will be formed at high temperature. Due to the expansion of the cracks and contact with air, under the microscope, the cracks are full of oxide skin and decarburized on both sides. The cracks are relatively thick, without detailed tips, relatively round and pure. Sometimes some forging cracks are relatively fine, and the cracks are semi decarburized rather than full decarburized.

Crater on weld surface is a common weld surface defect in submerged arc welding, which refers to the defect that the weld surface is partially lower than the normal weld surface.

Carbon steel pipe as a product must have a certain performance to meet the needs of the usage conditions. Improving the performance of the steel is two ways, First, adjusting the chemical composition of the steel alloying; the other is the heat treatment, heat treatment and shaping deformation combination of approaches. In the field of modern industrial technology, heat treatment to improve the performance of the steel still occupy a dominant position.

Heat-shrinkable diameter steel pipe production technology development began in the early nineteenth century oil development in the rise of the bicycle manufacturing industry, during the two world wars, ships, boilers, aircraft manufacturing after World War II thermal power boiler manufacturing, chemical industry development and oil and gas drilling and transportation, a strong impetus to the development of the steel industry in the varieties, yield and quality.

Straight seam submerged arc welded steel pipe used for the submerged arc welding process technology, the use of filler welding, submerged arc flux particle protection.

When crises break between austenite no metal precipitation, molybdenum has little effect on the mechanical properties at room temperature.

Straight seam steel pipe expanding is a process that a use of hydraulic or mechanical means forcing the steel pipe from the pipe wall bulged outward along the radial pressure molding process.

Spiral pipe manufacturers adopt advanced double submerged arc production process, easy to control weld quality and welding position can be achieved in the best position, not prone to the wrong side, partial and incomplete penetration welding defects.