1. Welding materials
In view of the working characteristics of the weldability of 15CrMoG steel, based on past experience and referring to the welding process cards provided abroad, two options can be selected for welding tests.
PlanⅠ: Welding preheating, using H13CrMoA (GB/T14957) welding wire, Ws welding primer, E5515-B2 (R307) electrode, arc welding cover surface, and local heat treatment after welding.
Plan II: Use ER80S-B2L welding wire, T1G welding primer, E309Mo-16 welding rod, the welding rod fills the arc welding cover, and no heat treatment is performed after welding.
Post weld heat treatment
The test piece welded using Scheme I shall be subjected to local high-temperature tempering treatment after welding. The heat treatment process is as follows: heating rate is 200℃/h, rising to 715℃ and holding for 1 hour and 15 minutes, cooling rate 100℃/h, cooling to 300℃ and then air cooling. Specifically, a JL-4 crawler electric heater (1146x310) is used to wrap the weld, and a layer of aluminum silicate cotton is used for insulation. The thickness of the insulation layer is 50mm. The temperature is controlled by a DJK-A electric heater automatic temperature controller.
15CrMo welding process
Preparation before welding
The test piece is made of 15CrMoG seamless steel pipe. Before welding, use an angle light machine to polish the inside and outside of the groove and the edge of the groove within 50mm until the metallic luster is exposed, and then clean it with acetone. Use manual tungsten arc welding to spot-weld six spots evenly along the circumference of the garden, and the length of each spot should be no less than 20m. Welding rods are baked according to specifications.
Welding process parameters
According to Plan I, preheating is required before welding, and the preheating temperature is selected from 150°C to 250°C. Use an oxygen-acetylene flame to heat the test piece. First use a temperature measuring pen to roughly judge the temperature of the surface of the test piece (estimate based on the speed of the color change of the handwriting). Finally, use a semiconductor point thermometer to measure it. At least three measuring points should be selected. , to ensure that the entire specimen reaches the required preheating temperature.
Welding process parameters of option 1
Weld bead name Welding method Welding materials Welding material specifications/mm welding current/A arc voltage/V Preheating and interpass temperature heat treatment specifications
Bottom layer arc welding H13CrMoA2.4/110/12
Filled layer electrode arc welding E5515-B2 in 3.2/85~90/23~25/150℃/
715℃x75min
Cover layer arc welding E5515-B23.2/85~90/23~25
Welding process parameters of scheme II
Weld bead name Welding method Welding material Welding material specification/mm welding current/A arc voltage/V pre
Specification for thermal and interpass temperature heat treatment
Bottom layer tungsten plate arc welding ER80S-B2L 2.4/110/12
Filled layer electrode arc welding E09M-16 in 3.2/90~95/22~24//
Cover layer arc welding E309Mo-16 3.2/90~95 /22~24
Post weld heat treatment
The test piece welded using Scheme I shall be subjected to local high-temperature tempering treatment after welding. The heat treatment process is as follows: heating rate is 200℃/h, rising to 715℃ and holding for 1 hour and 15 minutes, cooling rate 100℃/h, cooling to 300℃ and then air cooling. Specifically, a Type-4 belt electric heater (1146x310) is used to wrap the weld, and a layer of aluminum silicate cotton is used for insulation. The thickness of the insulation layer is 50mm. The temperature is controlled by a DJK-A electric heater automatic temperature controller.
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