According to 15CrMo Steel weldability, on-site working characteristics of high pressure pipeline and reference to welding process card provided by abroad, we select two kinds of schemes to conduct the welding test based on past experience.
SchemeⅠ: First, conduct the welding preheating method. Then, select ER80S - B2L welding wire, T1G welding backing, E8018 - B2 welding rod and arc welding capping. Finally, conduct partial heat treatment after welding.
SchemeⅡ: Choose ER80S - B2L welding wire, T1G welding backing, E309Mo - 16 welding rod. Then, fill in arc welding capping with welding rod. Note: it can not be conducted heat treatment after welding.
Type C Mn Si Cr Ni Mo S P b/Mpaδ, %
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. Welding preparation
The test specimen is adopted 15CrMo steel tube, and its specification isφ325 x 25.
Polish the groove inside and outside and the groove edge with the scope of 50 mm until it shows the metallic luster before welding, and then clean it with acetone.
The test specimen is at the horizontal fixed position, and its end clearance is four mm. There are six spots along the round by the manual tungsten argon arc welding. The fixed length of each spot should not be less than 20 mm.
E8018 - B2
E309Mo - 16
3. Welding process parameters
According to the scheme Ⅰ, it needed to preheating before welding. According to the calculation formula for preheating temperature put forward by Tto – Bessyo:
To=350√[C]-0.25(℃), To - preheating temperature, ℃.