本发明公开了一种适用低温的X80大口径厚壁直缝埋弧焊管及其制造方法，焊管母材化学组成按照质量百分比为C：0.04~0.08%、Si：0.15~0.30%、Mn：1.60~1.85%、S：≤0.004%、P：≤0.010%、Ni：0.15~0.30%、Cr：0~0.30%、Cu：0.1~0.3%、Nb：0.05~0.10%、V：0.005~0.04%、Ti：0.015~0.03%、Mo：0.10~0.35%、Al：0.02~0.05%、N：≤0.008%、B：0.0003~0.0005%，制造方法包括：按照所上述化学组成的质量百分比制备热轧钢板，钢板超声波检验、铳边、预弯边、JCO成型、预焊、内焊、外焊、焊缝X射线检测、钢管扩径、静水压试验、焊缝超声波检测、管端X射线检测、倒棱、管端磁粉检测、外观质量检查。本发明的焊管焊接接头具有良好的低温韧性，可以在制管后不对焊管进行热处理的前提下，直接在-45℃及更低温度下使用。

The invention discloses a X80 large-diameter thick-walled longitudinal submerged arc welded pipe suitable for low temperature and a manufacturing method. The chemical composition of the base material of the welded pipe is C: 0.04~0.08%, Si: 0.15~0.30%, and Mn: 1.60 according to mass percentages. ~1.85%, S: ≤0.004%, P: ≤0.010%, Ni: 0.15~0.30%, Cr: 0~0.30%, Cu: 0.1~0.3%, Nb: 0.05~0.10%, V: 0.005~0.04% , Ti: 0.015~0.03%, Mo: 0.10~0.35%, Al: 0.02~0.05%, N: ≤0.008%, B: 0.0003~0.0005%, the manufacturing method includes: preparing the hot rolling according to the mass percentage of the above chemical composition Steel plate, steel plate ultrasonic inspection, blasting, pre-clamping, JCO forming, pre-welding, internal welding, external welding, weld X-ray inspection, steel pipe expansion, hydrostatic pressure test, weld ultrasonic inspection, pipe end X-ray inspection , Chamfering, pipe end magnetic particle inspection, appearance quality inspection. The welded joint of the welded pipe of the present invention has good low-temperature toughness, and can be directly used at -45°C and lower temperature under the premise that the welded pipe is not heat-treated after the pipe is made.