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Welding method for controlling hardness of welding affected zone of low alloy steel for petroleum pipeline
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A technology of welding affected area and low alloy steel, applied in welding equipment, applications, household appliances, etc., can solve problems such as embrittlement cracks, and achieve the effect of reducing hardness and improving microstructure and properties
Active Publication Date: 2016-10-26
XIAN SUNWARD AEROSPACE MATERIAL CO LTD
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Most of the bimetal composite pipes used in offshore oil use low-alloy steel X65QO as the base pipe, and the liner pipe is 316L. When the pipe end is treated, according to the principle of equal strength matching, the ER309LMo welding consumable is selected as the base transition welding consumable, and the welding of ER309LMo and X65QO Finally, due to carbon migration, the hardness of the heat-affected zone of the weld is very high. The hardness value exceeds 345HV10, and the highest can reach 450HV10. Embrittlement cracks, but the current welding process can not solve this problem
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Embodiment 1
[0015] Using Φ1.0AWS A5.09ER309LMo welding wire, the preheating temperature is controlled at 80°C, the welding current of the bottom layer is 150-160A, the welding speed is 60cm / min, the welding heat input is 3.0-6.0KJ / cm, and the width of the bottom layer weld Controlled at 1-2mm, fusion ratio controlled between 0.25-0.30, welding current of cover layer 130-150A, welding speed 45cm / min welding, thickness of weld seam of cover layer controlled at 2-3mm.
[0016] The post-weld hardness of Example 1 is compared with the existing technology as shown in Table 1.
[0017] Table 1 Example 1 post-weld hardness test results compared with existing technology
[0018]
Embodiment 2
[0020] Using Φ1.0AWS A5.09 ER309LMo welding wire, the preheating temperature is 120℃, the welding current of the bottom layer is 110-130A, the welding speed is 30cm / min, and the welding heat input of 4.0-5.0KJ / cm is used to make the bottom layer weld The width is controlled at 1-2mm, the fusion ratio is controlled between 0.25-0.30, the welding current of the cover layer is 150-160A, the welding speed is 60cm / min, and the thickness of the weld seam of the cover layer is controlled at 2-2.5mm.
[0021] The post-weld hardness of Example 2 is compared with the existing technology as shown in Table 2.
[0022] Table 2 Example 2 post-weld hardness test results compared with existing technology
[0023]
Embodiment 3
[0025] Φ1.0AWS A5.09 ER309LMo welding wire is used, the preheating temperature is 100°C, the welding current of the bottom layer is 130-140A, the welding speed is 50cm / min, and the welding heat input of 3.0-4.0KJ / cm is used to make the bottom layer weld The width is controlled at 1-2mm, the fusion ratio is controlled between 0.25-0.30, the welding current of the cover layer is 130-140A, the welding speed is 50cm / min, and the thickness of the weld seam of the cover layer is controlled at 2-2.5mm.
[0026] The post-weld hardness of Example 3 is compared with the existing technology as shown in Table 3.
[0027] Table 3 Example 3 post-weld hardness test results compared with existing technology
[0028]
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Abstract
A welding method for controlling the hardness of a welding affected zone of low alloy steel for a petroleum pipeline is characterized in that medium-frequency induction heating equipment is adopted for preheating, a stainless-steel argonarc welding wire is adopted, the welding current of a backing welding layer is 110-160 A, the welding speed is 30-60 cm / min, the thickness of a backing weld is 1-2 mm, the penetration ratio is 0.25-0.30, and the input quantity of weld heat is 3.0-6.0 KJ / cm during the welding process; and the welding current of a cosmetic welding layer is 130-160 A, the welding speed is 45-60 cm / min, the thickness of a cosmetic weld is 2-3 mm, the penetration ratio is 0.25-0.30, and the input quantity of weld heat is 4.0-6.0 KJ / cm during the welding process. According to the method, under the condition that no post-weld heat treatment is performed, the structures of the welds are controlled by controlling the input quantity of heat and the penetration ratios during the welding processes to improve the structure property of the weld heat affected zone, so that the purpose of hardness reduction is achieved.
Description
technical field [0001] The invention belongs to the technical field of production of bimetallic composite pipes for offshore oil, and in particular relates to a welding method for controlling the hardness of a welding-affected zone of low-alloy steel for oil pipelines. Background technique [0002] The current international standard NACE MR0175-2003 "Metallic Materials Resistant to HydrogenSulfideStress Corrosion Cracking and Stress Corrosion Cracking for Oilfield Equipment" specifies the maximum hardness value of the welding area of low alloy steel: the maximum hardness in the welded state is 22HRC (about 250HV10). Most of the bimetal composite pipes used in offshore oil use low-alloy steel X65QO as the base pipe, and the liner pipe is 316L. When the pipe end is treated, according to the principle of equal strength matching, the ER309LMo welding consumable is selected as the base transition welding consumable, and the welding of ER309LMo and X65QO Finally, due to carbon...
Claims
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Application Information
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