In today's industrial field, large-diameter thick-walled steel pipes are more and more widely used, especially in extreme environments such as high pressure, high temperature, and high corrosion. As a high-alloy steel, 12Cr1MOV steel is widely used in the production of large-diameter thick-walled steel pipes because of its excellent mechanical properties and corrosion resistance. However, welding this material is not an easy task and requires special processes and technologies. This article will introduce the welding process of 12cr1mov large-diameter thick-walled steel pipe in detail.
When welding 12Cr1MOV large-diameter thick-walled steel pipes, you first need to understand the characteristics of this material. 12Cr1MOV steel is a low-carbon alloy steel that contains high alloying elements such as chromium, molybdenum, and vanadium, which give the material excellent high-temperature strength, toughness, and corrosion resistance. However, this material is prone to embrittlement, hardening, softening, and weld cracks in the heat-affected zone during welding. Therefore, it is crucial to choose the right welding materials and processes.
The selection of the welding process should be determined according to the specific engineering requirements, the thickness of the base metal, the form of the welded joint, and the welding position. Generally, submerged arc automatic welding or gas shielded welding is used when welding thick-walled steel pipes. For 12Cr1MOV high-alloy steel, considering its high content of alloying elements, gas shielded welding should be preferred, especially argon arc welding or mixed gas shielded welding.
Equally important is the preparation before welding. The base metal is pre-treated to remove oil, rust and oxide scale on the surface to ensure the quality of welding. Choose the appropriate bevel form according to the actual situation, and ensure the bevel processing accuracy. In addition, the welding equipment is debugged to ensure that it is in good working order.
In the welding process, controlling the welding parameters is key. The right welding current, voltage and welding speed ensure the quality of the weld and prevent the formation of thermal cracks. At the same time, the use of appropriate preheating and interlayer temperature control can effectively reduce the scope of the heat-affected zone and avoid embrittlement and hardening problems. In addition, it is crucial to choose the right filler material when welding. According to the characteristics of 12Cr1MOV steel, filler materials with high strength, good toughness and corrosion resistance should be selected.
After the welding is completed, the necessary post-welding treatment is also an important part of ensuring the welding quality. This includes a visual inspection of the weld, non-destructive testing and, if necessary, strength testing. At the same time, post-weld heat treatment is selected as needed to further stabilize the performance of the welded joint.
In actual production, there are some other problems that need to be paid attention to when welding 12cr1mov large-diameter thick-walled steel pipes. For example, due to the high alloying properties of the material, defects such as porosity and slag inclusion are prone to occur during the welding process. Therefore, the flow rate and composition of the shielding gas should be strictly controlled during welding to ensure a good gas protection effect. In addition, in order to prevent the formation of cracks, appropriate post-heat treatment and slow cooling measures can be taken.
To sum up, welding 12Cr1MOV large-diameter thick-walled steel pipes requires comprehensive consideration of material characteristics, process selection, equipment commissioning, parameter control and post-welding treatment. Only by mastering these key technologies can we ensure high-quality welding results and meet the needs of engineering applications. In actual production, it is of great significance to continuously accumulate experience and continuously improve the welding process to improve production efficiency and product quality.