Welding Method Selection for Carbon Structural Steel and Low Alloy High Strength Steel
In recent years, under the background of energy conservation, emission reduction,and quality improvement requirements in the steel industry, the development and application of welding knowledge and technology to carbon steel and low alloy high-strength steel has been widely promoted, and the variety and complexity of welding methods and electronic processes are increasing. Therefore, for steel structures, welding methods should be selected reasonably when designing welding technology and procedures.
1. Selection of welding methods for carbon steel structures
(1) Major butt welding
When welding parts with a plate thickness of over 10mm, the major butt welding should be used as the priority. When the plate thickness is <10mm, fillet welding can be used.
(2) Submerged arc welding
It is suitable for welding thick carbon steel plates. The weld forming conditions are good and the welding speed is fast.
(3) Gas shielded arc welding
It is suitable for welding medium-thick or thin carbon steel plates, and it has certain flexibility and mobility.
(4) Manual arc welding
It is suitable for welding parts with small size and low thickness, and can be used in field operations or repair welds.
(5) Flux cored wire welding
It can be used for welding with stainless steel, ferritic steel, wear-resistant steel and low-temperature steel, and the welding speed is fast.
(6) Atomic hydrogen arc welding
It is suitable for welding high-quality and precise carbon steel structures, and especially for welding large-scale steel structures with high requirements on welding quality.
2. Selection of Welding Processes for Low-alloy High-strength Steel
Low-alloy high-strength steel welds are mostly structural steels with a yield strength of 490MPa and an atmospheric corrosion resistance, for which the weld metal toughness and the heat affected zone toughness are relatively low due to carbon and sulfur content. The specific welding process should be selected according to the requirements of the actual engineering on the tensile strength, bending strength, impact toughness, fatigue strength and welding temperature.
(1) Gas shielded arc welding
It is suitable for welding parts with a thickness of less than 10mm. It has good welding formability and strong adaptability, but the welds are prone to hardening and cracking, and preheating is usually required.
(2) Submerged arc welding
It is suitable for welding with carbon steel and low-alloy high-strength steel plates with a thickness of more than 10 mm. The weld forming conditions are good, the welding speed is fast, and the welds are rarely cracked.
(3) Electroslag welding
It is suitable for welding large-section and medium-thick plate parts of low-alloy high-strength steel structure, as well as for repair welding that requires high welding quality.
(4) TIG welding
It is suitable for welding of small parts and parts with complex shape, and for repair welding of important parts.
(5) Flux-cored arc welding
It is suitable for steel structures with a thickness of less than 8mm, and the welding speed is fast.
In summary, due to the different application objects of welding methods and technological processes for carbon structural steel and low alloy high strength steel, it is necessary to select reasonable welding methods and technological processes when designing welding technology and procedures. In order to obtain high-quality welds and improve production efficiency, careful selection and rational application of welding methods and technological processes is essential.
