分析镀锌板常见的三种缺陷及改进方法 

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彩钢镀锌板钢板经冷变形和连续退火后，在表面镀上均匀的锌层，从而获得耐蚀性好的钢板即镀锌钢板，广泛应用于建筑、家电、汽车等行业。由于镀锌板生产工艺复杂，工序繁多，可能会产生各种质量缺陷，影响外观和用户使用。
分析了镀锌板常见的滑移线、锌流型、锌花不均匀等缺陷，并从实际出发给出了现场解决办法。
01滑移线
一。形态特征。
在随后的加工过程中，板面上会出现类似线条的暗线，有时有凸起和明显的触感，有时看不清。
2。原因分析。
在实际生产过程中，滑移线产生的主要原因有：
（1） 板形率设置不合理。经过一定的平面变形后，退火钢板中产生大量的可移动位错，使位错摆脱了溶液C、N原子的束缚，在较小的应力作用下变形可以继续，从而消除了屈服平台。
在一定的平整度下，屈服强度随着平整度的提高而降低，直至达到最低点，此时屈服平台消失；随着平整度的进一步提高，屈服强度再次提高，加工硬化不断增加，变形能力下降，工作性能变差减少。
（2） 自然衰老。镀锌钢板经退火压扁后，消除了屈服平台。在室温下放置很长时间后，碳、氮原子再次在位错周围扩散，形成“科里奥利气团”，导致屈服平台的重新出现。
（3） 人工老化。镀锌钢板的屈服平台在高温下会重新出现，需要涂漆烘烤或涂漆加热。
三。改进措施。
（1） 合理设置板形不仅可以消除屈服平台，而且可以避免屈服强度的过度提高，降低材料的成型性能。
（2） 与连续退火相比，加热冷却速度慢（一般为20%/H40~C/h），保温时间长。退火后钢中大量C以FEC的形式析出，N原子以A1N的形式完全析出，大大减少了钢中固溶体原子的数量。
（3） 采用先进的连续退火工艺，如R-OA工艺，通过快速冷却和低温冷却，提高了FEC成核和生长的驱动力，使固溶体C以FEC的形式析出，提高了时效抗力。
（4） 热轧可以在较低的温度下加热板坯，同时配合我国高新技术产品的温卷工艺，促进A1N、Fe、C的析出和生长，有效降低钢板中固溶态N的含量。
（5） 采用超低碳无间隙原子钢，钢中C、n元素含量极低。同时，Ti、Nb等强碳氮化物形成元素能进一步固定C、N原子，完全解决老化问题。

After cold deformation and continuous annealing, the steel plate is coated with a uniform zinc layer on the surface, so as to obtain the steel plate with good corrosion resistance, i.e. galvanized steel plate, which is widely used in construction, home appliances, automobile and other industries. Due to its complex production process and various processes, galvanized sheet may produce a variety of quality defects, affecting the appearance and user use.

In this paper, the common defects of galvanized sheet, such as slip line, zinc flow pattern and uneven zinc flower, are analyzed, and the field solutions are given from the practical point of view.
01 slip line
1. Morphological characteristics.
In the subsequent processing, the line like dark lines appear on the board surface, sometimes with bulge and obvious touch, sometimes not clearly visible.
2. Cause analysis.
In the actual production process, the slip line is mainly caused by the following reasons:
(1) The setting of flatness rate is unreasonable. After a certain amount of flat deformation, a large number of movable dislocations are produced in the annealed steel plate, which make the dislocations get rid of the binding of solution C and N atoms, and the deformation can continue under a small stress, thus eliminating the yield platform.
Under a certain flatness, the yield strength decreases with the improvement of flatness until it reaches the lowest point, at which time the yield platform disappears; with the further improvement of flatness, the yield strength increases again, the work hardening increases continuously, the deformation ability decreases, and the work performance decreases.
(2) Natural aging. After annealing and flattening, the yield platform of the galvanized steel plate has been eliminated. After being placed at room temperature for a long time, the C and N atoms spread around the dislocation again to form "Coriolis air mass", which leads to the re emergence of the yield platform.
(3) Artificial aging. The yield platform of galvanized steel sheet which needs to be painted and baked or coated and heated will reappear at high temperature.
3. Improvement measures.
(1) Reasonable setting of flatness can not only eliminate the yield platform, but also avoid the excessive increase of yield strength and decrease the molding performance of materials.
(2) Compared with continuous annealing, the speed of heating and cooling is slow (generally 20% / H40 ~ C / h), and the holding time is long. After annealing, a large amount of C in steel is precipitated in the form of FEC, and N atoms are fully precipitated in the form of A1N, which greatly reduces the number of solid solution atoms in steel.
(3) Adopting advanced continuous annealing technology, such as R-OA technology, through rapid cooling and low-temperature cooling, the driving force of FEC nucleation and growth is improved, the solid solution C is precipitated in the form of FEC, and the aging resistance is increased.
(4) Hot rolling can heat the slab at a lower temperature, at the same time, it can promote the precipitation and growth of A1N, Fe, C, and effectively reduce the content of solid solution N in the steel plate by cooperating with the warm coiling process of the new high-tech products of high-74-china.
(5) Using ultra-low carbon interstitial free atomic steel, the steel contains very low amount of C and n elements. At the same time, strong carbon nitride forming elements such as Ti and Nb can further fix the C and N atoms, which can completely solve the aging problem.