Weldability of 40cr steel pipe

How about the weldability of 40Cr steel pipe?
It is easy to segregate during crystallization and is more sensitive to crystallization cracks (a kind of hot cracks). It is easy to crack in the craters and concave parts of the weld during welding. The 40cr steel pipe has a high carbon content, and it is easy to obtain a hardened structure (martensitic structure) sensitive to cold cracks during rapid cooling. In the superheating zone, when the cooling rate is large, it is easy to form hard and brittle high-carbon martensite and make the superheating zone brittle.

Main points of welding technology of 40cr steel pipe
1. 40cr steel pipes are generally welded in the annealed (normalized) state.
2. Welding method is not limited
3. Increase the preheating temperature appropriately with larger line energy. Generally, the preheating temperature and the interlayer temperature can be controlled between 250～300℃.
4. The welding material should ensure that the composition of the deposited metal is basically the same as the base material, such as J107-Cr
5. Tempering and heat treatment should be carried out in time after welding. If it is difficult to carry out quenching and tempering treatment in time, intermediate annealing or holding at a temperature higher than preheating for a period of time can be performed to eliminate the diffusion of hydrogen and soften the structure. For products with complex structure and many welds, an intermediate annealing can be performed after welding a certain number of welds.
 

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