喷雾冷却强度对X80管线钢多丝埋弧焊接头组织与性能的影响

Effect of spray cooling intensity on microstructure and mechanical properties of X80 pipeline steel multi-wire submerged arc welded joints

  • 摘要:
    目的 在X80管线钢中厚板多丝埋弧焊接过程中应用喷雾冷却技术,是为了通过气压调节和水流量控制实现冷却强度的精准调控。
    方法 基于室温拉伸、低温冲击、显微硬度试验等力学手段,以及金相显微镜、扫描电镜等表征方式建立多维度评价体系,分析不同喷雾冷却强度条件对焊接接头的力学性能和微观组织的影响规律。
    结果 结果表明,喷雾冷却可以加快焊缝和热影响区的冷却速率,缩小热影响区面积,冷却效果随气压增加先提高后降低,随水流量增加而提高。焊缝区的多边形铁素体在喷雾冷却作用下由长链条状转变为较短粗的块状,粗晶区的粒状贝氏体晶粒尺寸减小,板条贝氏体占比增加。相比于自然冷却状态,焊缝冲击吸收能量在喷雾冷却气压为0.2 MPa、水流量为0.6 L/min时最高达到193.7 J,提高了23.5%,剪切断面率由83%提高到92%。
    结论 喷雾冷却可以细化焊缝和热影响区的晶粒,提高焊缝冲击韧性。气压为0.2 MPa、水流量为0.6 L/min时冷却效果最佳。

     

    Abstract: Objective Spray cooling technology is applied in the process of multi-wire submerged arc welding of X80 pipeline steel medium and heavy plate, the aim is to achieve precise control of cooling intensity through air pressure regulation and water flow control. Methods A multi-scale evaluation system is established based on mechanical means such as room temperature tensile test, low temperature impact test and microhardness test, as well as OM, SEM and other characterization methods. The effects of different spray cooling intensity conditions on the mechanical properties and microstructure of welded joints are analyzed. Results The results show that spray cooling can accelerate the cooling rate of weld and HAZ, reduce the area of HAZ, and the cooling effect increases first and then decreases with the increase of air pressure, and increases with the increase of water flow. Under the effect of spray cooling, the polygonal ferrite in the weld zone changes from long chain strip to short and coarse block, the grain size of granular bainite in the coarse grain zone decreases, and the proportion of lath bainite increases. Compared with the natural cooling state, the weld impact absorbed energy reached 193.7 J at the spray cooling air pressure of 0.2 MPa and the water flow rate of 0.6 L/min, which increased by 23.5%, and the shear section rate increased from 83% to 92%. Conclusion Spray cooling can refine the grain of weld and HAZ, and improve the impact toughness of weld. The cooling effect is the best when the air pressure is 0.2 MPa and the water flow is 0.6 L/min.

     

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