译文：
尽管铸造技术已经有了巨大的发展，并利用计算机技术辅助优化结构设计和浇铸过程的流体几何设计，但是要达到1类或2类接受标准的X射线/MT或PT质量要求仍然是极端困难的，而这些都是核电站、热电站或石化工业内的苛刻环境所要求的标准。因此就需要进行焊接改进。但是，在焊补后，铸件阀门的整体质量和可靠性就变得难于保证。有时所有这些问题都遗留在铸件焊接金属框架里。测试杆通常针对每个温度，但是它们的分析可能是不确定的。即使圆形测试杆表明化学特性和物理特性是可接受的，逐渐本身仍然可能存在难于察觉的有损强度或防腐能力的内部缺陷 根据锅炉法典（美国）第IX节的要求，在使用过程中需要定期进行检查的内容包括，逐渐金属的焊缝，管道焊缝。焊补位置的纪录因此必须保存，所以在工厂运行过程中，故障发生的信号可能与原始的制造条件和标准有关。 在铸造过程中，浇铸到模腔内的金属在凝固过程中可能会产生收缩、分离或气孔，这些问题使得“浇铸”铸件无法被苛刻环境应用领域所接受。收缩发生在两个过程中，温度高于熔点的金属冷却时产生收缩，随后在凝固过程中进一步收缩。{dy}次增加熔化金属补偿，但是固态冷却过程中的补偿就要靠加大尺寸。 分离，或熔化物的化学分离，是在模腔内壁固化出一层后的凝固过程中发生，在很长的温度变化期间，低流动性使得小固体颗粒-晶体-以树状结构形成和生长。最初的晶体，紧靠模腔内壁，合金含量最少。在里面的核心部分，合金含量比较高，这使得预想的成分变得没有什么相似性。在每个晶体枝杈内，也存在着微观偏析。结果导致微孔、再生相沉淀和金属和非金属成分混杂。 在冷却过程中，溶液中的气体逸出造成多孔性，或被截留在晶体枝杈之间形成微小气孔。此外，作为晶体固化和量的收缩，熔化物的替代品一定会沿着交错的晶体网络流过一段曲折的路程。流动阻力可能太高，从而导致微孔和多孔。 铸件内部的其它一些缺点是，凝固过程中，在不均匀收缩造成的应力集中和接近熔点温度下金属的低强度的综合作用下，出现的清晰裂缝和热撕裂。较低的铸造温度会形成冷疤，熔化金属出现的沙粒或炉渣的累积会导致污点。低级的铸造作业也可能造成其它缺陷。 铸件的改进要满足X射线质量的要求就要靠缺陷部位的磨削，焊补，热处理和重复测试和检验。即使在这种情况下，阀座和垫圈面或碰焊端可能会显示需要通过重焊和机加工的细线裂缝。

“ To avoid damage to the valve metal flow and crystal quality of the casting”是由提供的国际阀门新闻，译文仅供参考。另外，中国隔膜阀网还提供相关产品搜索：、、、、等。

原文：
Although casting technology has made tremendous development and optimize the structure using computer aided design and casting process, fluid geometrical design, but to achieve the acceptance of Class 1 or Class 2 Standard X-ray / MT or PT quality requirements is still extremely difficult , which are nuclear power plants, thermal power stations or petrochemical industry in the harsh environment required standards. Hence the need for welding to improve. However, in the welding repair of casting the overall quality and reliability of the valve becomes difficult to guarantee. Sometimes all of these issues are left in the castings welded metal framework. Usually the temperature for each test shot, but their analysis may be uncertain. Even if the round test bar showed that the chemical properties and physical characteristics are acceptable, there may still be difficult to gradually their perceived ability to undermine the strength or corrosion of internal defects According Boiler Code (United States) The requirements of Section IX, in the course of regular inspections of the contents need to include the gradual metal weld, pipe weld. Welding position record must be preserved, so the plant is running, the fault signal may be related to the original manufacturing conditions and standards. In the casting process of metal casting to the mold cavity during solidification may cause shrinkage, separation, or pores, making them "cast" casting harsh environment applications can not be accepted. Shrinkage occurs in two processes, the temperature is higher than the melting point of the metal cooling contraction, followed by further contraction in the solidification process. The first increase in compensation for the molten metal, but the cooling process of solid-state depends on increasing the size of the compensation. Separation, chemical separation or melt is solidified in a cavity wall layer occurs after the solidification process, the temperature in a very long period of low liquidity makes the small solid particles - crystal - the formation and growth of a tree structure . The initial crystal, close to the cavity wall, alloy content at least. Inside the core of the higher alloy content, which makes the desired component becomes no similarity. Within each crystal twigs, there are micro-segregation. A result, porous, renewable and non-metallic phase precipitation and metal elements mixed. In the cooling process, the solution caused by the porous gas escape, or trapped in tiny pores between the crystals twigs. In addition, as the amount of crystal solidification and shrinkage, melt will substitute for the crystal along the cross section of the network flow through the twists and turns away. Flow resistance may be too high, resulting in porous and porous. Casting a number of other weaknesses within the solidification process, resulting in uneven shrinkage and stress concentration close to the melting temperature of metals under the combined effect of low intensity, there's a clear and hot tear cracks. Lower casting temperature of the cold scar formation, molten metal or slag sand appears cumulative lead stain. Lower the casting operation may also cause other defects. Castings X-ray quality improvement to meet the requirements of the position depends on the grinding defects, welding repair, heat treatment and repeat testing and testing. Even in this case, the valve seat and the washer face or touch solder side may show through heavy welding and machining of thin cracks.