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首页> 外文学位 >Laser welding of 200-series stainless steels: Solidification behavior and microstructure characteristics.
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Laser welding of 200-series stainless steels: Solidification behavior and microstructure characteristics.

机译：200系列不锈钢的激光焊接：凝固行为和显微组织特征。

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摘要

The welding of metals and alloys with a CO{dollar}sb2{dollar} laser differs from the arc welding process in that the solidification and cooling of the melt occurs very rapidly. As a result, the final product microstructure of the laser weld metal will vary from that produced by arc welding processes, and from the slow cooled melt produced by other processes such as casting. Also, the rapidly cooled microstructure produced by the laser welding process cannot be predicted by the constituent diagrams as is true in the case of the equilibrium structure produced during slow cooling. Since the welding of some metals and alloys by the CO{dollar}sb2{dollar} laser is relatively new, more studies are needed to understand the effect of rapid cooling rates on the microstructural features, morphologies and solidification behavior.; The role of the cooling and solidification rates on the final product microstructure has been investigated through this research. Slow cooling experiments using melting and casting techniques, and rapid cooling experiments using the laser welding process have been conducted on type 201 and type 202 stainless steels and the resultant structures were investigated and related to the cooling rate. An empirical equation relating cooling rate to the secondary dendrite arm spacing was determined and the 201 and 202 stainless steel laser weld metal cooling rate has been estimated. In the slow cooling experiments, the melt solidified as primary ferrite and the delta-ferrite morphology varied, depending on the cooling rate, from a lacy structure to a skeletal structure. The laser weld metal structure solidified as primary austenite and the structure consists of austenite dendrite columns surrounded by delta-ferrite rims. The change in the solidification mode from primary ferrite to primary austenite was related to the excessive undercooling caused by rapid cooling during laser welding. Moreover, the amounts of austenite and ferrite in the laser weld metal, the primary and secondary dendrite arm spacings, the chemical composition, the size of the heat affected zone, and the depth and width of weld metal, were all related to the solidification rate during laser welding.
机译：用CO {dollar} sb2 {dollar}激光器进行金属和合金的焊接与电弧焊工艺的不同之处在于，熔体的凝固和冷却非常迅速。结果，激光焊接金属的最终产品微观结构将不同于电弧焊过程产生的微观结构，以及不同于其他过程（例如铸造）产生的缓慢冷却的熔体的微观结构。而且，由激光焊接过程产生的快速冷却的微观结构不能通过组成图来预测，正如在缓慢冷却期间产生的平衡结构的情况下那样。由于用CO {dollar} sb2 {dollar}激光焊接某些金属和合金是相对较新的技术，因此需要更多的研究来了解快速冷却速率对显微组织特征，形貌和凝固行为的影响。通过这项研究，研究了冷却和固化速率对最终产品微观结构的作用。已经对201型和202型不锈钢进行了使用熔融和铸造技术的慢速冷却实验，以及使用激光焊接工艺的快速冷却实验，并对所得结构进行了研究并与冷却速率有关。确定了将冷却速率与次级枝晶臂间距相关联的经验公式，并估算了201和202不锈钢激光焊接金属的冷却速率。在慢速冷却实验中，熔体固化为一次铁素体，δ-铁素体形态随冷却速率的不同而变化，从花边结构到骨架结构。激光焊接金属结构凝固为一次奥氏体，该结构由被铁素体铁素体边缘包围的奥氏体枝晶柱组成。从一次铁素体到一次奥氏体凝固模式的变化与激光焊接过程中快速冷却导致的过冷度过高有关。此外，激光焊接金属中奥氏体和铁素体的数量，一次和二次枝晶臂间距，化学成分，热影响区的大小以及焊接金属的深度和宽度都与凝固速率有关。在激光焊接过程中。

著录项

  • 作者

    Abdulgader, Saleh A.;

  • 作者单位

    The Pennsylvania State University.;

  • 授予单位 The Pennsylvania State University.;
  • 学科 Engineering Metallurgy.; Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 1988
  • 页码 159 p.
  • 总页数 159
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 冶金工业;工程材料学;
  • 关键词

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