多级热处理对柔性立管用高强钢组织性能影响

为了探究高强度海洋柔性管铠装层用钢焊接接头失稳问题，以600 MPa级耐蚀钢为闪光对焊焊接母材，研究不同闪光留量与顶锻留量对接头显微组织及力学性能的影响规律. 结果表明，随顶锻留量增加，焊缝及热影响区粗晶区多边形铁素体含量增加，组织逐渐粗化，接头强度先增加后降低，顶锻留量大于5 mm，接头强度急剧恶化；随闪光留量的增加，焊缝及粗晶热影响区板条贝氏体组织逐渐粗化，接头强度逐渐增加后急剧下降，当闪光留量8 mm时，接头强度严重恶化. 二者都使断后伸长率逐渐提高，但顶锻留量对断后伸长率的影响较大. 闪光留量和顶锻留量为7 mm和4 mm时，焊接样品力学性能最优，热影响区针状铁素体板条宽度大约为0.59 μm，抗拉强度达到688 MPa，屈服强度达到586 MPa，断后伸长率为15%，拉伸断口形式为韧性断裂. 闪光留量与顶锻留量参数的适当匹配形成细小且弥散分布粒状贝氏体可以有效强化钢基体.

Blockchain in oil and gas industry: Applications,challenges, and future trends

In order to investigate the instability of welded steel joints for high-strength Marine flexible pipe armor, taking the hydrogen damage resistant corrosion resistant steel 600 MPa grade as the test object, and the effects of different flash allowance and upset allowance on the microstructure and mechanical properties of the joints were studied. The results show that with the increase of the upset allowance, the polygonal ferrite content of the weld and coarse grain zone in the heat-affected zone increases, and the microstructure gradually coarsens, and the joints strength increases firstly then decreases. When the flash allowance exceeds 5 mm, the joint strength deteriorates sharply. With the increase of flash allowance, the weld and heat-affected zone coarse-grained zone the bainite ferrite gradually coarser, and the joint strength gradually increases and then decreases sharply. When the flash allowance is 8 mm, the joint strength deteriorates seriously. Both of the parameters increase the elongation gradually, but the influence of the upset allowance on the elongation is greater. When the flash allowance and upset allowance are 7 mm and 4 mm, the mechanical properties of the welded samples are the best. The width of the ferrite lath in the heat affected zone is about 0.59 μm, the tensile strength is 688 MPa, the yield strength is 586 MPa, the elongation is 15%, and the tensile fracture form is ductile fracture. The fine and dispersedly distributed granular bainite can be formed by the matching of the flash allowance and the upset allowance parameters, which can effectively strengthen the steel matrix.