冷辊轧不锈钢翅片管制造难点的探讨(中)——再论冷加工对不锈钢管性能的劣化及控制

    Discussion on Manufacturing Difficulties Associated with Cold-rolled Finned Stainless Steel Tube for Heat Exchanger(PartⅡ)—Re-discussion on Deterioration of Performance of Stainless Steel Tube by Cold-working Process and Relative Control Measures

    • 摘要: 介绍丙烯酸的理化特性、制造流程及选材经验;分析翅片管制造方法及其标准化状态;探讨冷辊轧不锈钢翅片管的技术难点,提出改善方法。分析认为:冷加工状态直接应用的304钢翅片段塑性变形过量脆化且缺少有效的NDT检测是造成开裂泄漏的主要原因。缩短翅片高度,降低冷加工变形量;明确要求母管的退火软化状态;选择合理的辊轧预热(环境)温度及应变速率以控制形变感生马氏体(及/或孪晶)分布形态;采用快速的回复奥氏体相变热处理工艺值得探索。此外还必须通过严格的ET等NDT检验。

       

      Abstract: Described in the essay are the physiochemical properties, the manufacturing process flow and experience in material selection of the propylene,and analyzed are the manufacturing process for the finned tube,and the standardized status thereof.Discussed are the difficulties in cold-rolling process for the finned tube,and proposed accordingly are the countermeasures.Based on relevant analysis,it is identified that the propylene leakage via cracking is mainly caused by the over plastic deformation embrittlement of the finned section of the tube as made in the 304 steel, and directly put in service in the as-cold worked status, and lack of effective NDT inspection.Accordingly possible countermeasures are worth taking,including shortening the height of the fin,reducing the cold-work deformation amount,specifying expressive requirements for the anneal softening status of the mother tube,properly determining the pre-heating(ambient)temperature of the roll,and the strain rate so as to control the distribution morphology of the deformation-induced martensite(and/or the twin crystal),and adopting the heat treatment process for rapid recovery of the austenitic phase transition as well as conducting strict ET or NDT inspection.

       

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