1 welding material
In view of the weldability of 15CrMo steel and the working characteristics of high-pressure pipelines on site, based on past experience, we have selected two schemes for welding tests with reference to the welding process cards provided by foreign countries.
Solution I: Welding preheating, using ER80S-B2L welding wire, T1G welding base, E8018-B2 welding rod, electrode arc welding cover surface, local heat treatment after welding.
Scheme II: ER80S-B2L welding wire, T1G welding base, E309Mo-16 electrode, welding rod filling arc welding cover, no heat treatment after welding.
Model C Mn Si Cr Ni Mo SP δb/Mpa δ,%
ER80S-B2L≤0.05 0.70.41.2 <0.20.5 ≤0.025 ≤0.025 ≤500 25
E8018-B2 0.070.7 0.3 1.1 0.5 ≤0.04 ≤0.03 550 19
E309Mo-16≤0.12 0.5～2.5 0.9 22.0～25.0 12.0～14.0 2.0～3.0≤0.025≤0.035 550 25
2 Preparation before welding
The test piece is made of 15CrMo steel pipe with a specification of φ325×25.
Prior to welding, an angle grinder was used to polish the inside and outside of the groove and the edge of the groove to a thickness of 50 mm to expose the metallic luster, and then cleaned with acetone.
The test piece is a horizontal fixed position, the matching gap is 4mm, and six points are uniformly spot-welded along the circumference by manual tungsten argon arc welding, and the length of each point is not less than 20mm.
Welding rod type baking temperature holding time
E8018-B2 300 °C 2h
E309Mo-16 150 °C 1.5h
3 welding process parameters
According to the scheme I, preheating is required before welding, and the formula for calculating the preheating temperature is proposed according to Tto-Bessyo et al.
To=350√[C]-0.25(°C) where To is the preheating temperature, °C.
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