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Compare the BBN Q345R steel and 20 steel welding properties

Q345R low-alloy high-strength steel is the most widely used and used steel plate for pressure vessels. It has good comprehensive mechanical properties and process properties. It is widely used in boilers, petroleum, chemical industry, power stations and other industries. Equipment and components such as converters, reactors, separators, air ducts, liquefied gas tanks, gas drums, liquefied petroleum gas cylinders, high gas pipes of hydropower stations, and turbine volutes.

20 steel is a high-quality carbon steel with low strength, good toughness, plasticity and weldability.

Since Q345R steel contains a certain amount of alloy elements, its hardening and cold cracking tendencies are larger than those of low carbon steel. Therefore, when welding Q345R steel at room temperature, adopt suitable welding materials and conventional techniques (without preheating), generally no hardened structure will appear in the weld seam and heat-affected zone, and the probability of welding cold cracks is small.

When the thickness of the welding workpiece is large, it is necessary to properly control the welding heat input and the interpass temperature to avoid the appearance of martensitic structure in the weld seam and heat-affected zone. If necessary, perform post-weld heat treatment to eliminate welding stress.

The crack sensitivity coefficient and carbon equivalent of 20 steel are small, the hardening tendency and cold cracking tendency of the material are small, and the welding performance is excellent. The conventional process method does not require preheating, and a better welded joint can be obtained.