青海华信锅炉有限公司|青海燃煤锅炉|青海燃气锅炉|青海锅炉公司|青海哪个品牌锅炉好
 1.苛性脆华现象
苛性脆华是属于晶间腐蚀，即发生在金属晶粒之间的腐蚀，金属发生这种腐蚀从表面上很难发现，只能通过专门得金属探伤仪器方能查出。
2.苛性脆化部位
苛性脆化容易发生的部位是在锅炉汽包的铆钉口及胀管口。在锅炉的钢板上，苛性脆化的裂纹在铆钉或胀管口周围，呈现放射状发展，有的由一个孔扩裂到另一个孔。
3.苛性脆化机理
金属构件的局部在高应力作用下，使晶粒与晶粒边缘产生电位差，形成腐蚀电池。此时晶粒边缘的电位比晶粒本身的电位底，因此边缘处为阳极，金属原子沿边缘溶解，因而使腐蚀沿着晶粒间发展。
4.产生苛性脆化的条件
锅炉金属发生苛性脆化是由下列条件共同作用下引起的：
锅水中含有较高浓度的游离碱(一般为氢氧化钠)。
在锅炉的结构上有造成锅水局部高度浓缩的条件，如在铆钉缝隙处，由于接合不严密，锅水容易在这些局部地方发生急剧浓缩。
在金属中有接近于它的屈服点的拉伸应力。
上述三个条件中，缺少任何一项都不可能使锅炉产生苛性脆化。
5.苛性脆化的防止
防止锅炉苛性脆化方法，除了改变锅炉的制造工艺(如将铆接及胀管改成焊接)，提高加工质量(如消除锅炉安装上的应力及缝隙)之外，就是从化学方法着手，控制好锅水中的游离碱，消除锅水的侵蚀性。

    1. The caustic embrittlement phenomenon of China
Caustic embrittlement China belongs to intergranular corrosion, which occur in the m e t al corrosion between grains, m e t als occur this kind of corrosion on the surface it is hard to find, only through specialized m e t al detection instrument in order to find out.
    2. The caustic embrittlement
Caustic embrittlement in boiler steam drum is prone to part of the rivet hole and tube expanding. On boiler steel plate, caustic embrittlement cracking in the tube around the mouth, rivets or radial development, some by a hole expansion crack into another hole.
    3. The mechanism of caustic embrittlement
Local under high stress of m e t al components, make the grain size and grain edge generate an electrical potential difference, form the corrosion cell. The grain potential than grain is potential on the edge of the bottom, so the edges as the anode, m e t al atoms along the edge of the dissolve, so that between corrosion along the grain development.
     4. Produce caustic embrittlement
Boiler m e t al in caustic embrittlement was caused by a under the following conditions:
Pot of water containing relatively high concentrations of free alkali (sodium hydroxide) in general.
In the structure of boiler has caused a pan of water on the local conditions of highly concentrated, such as gaps in the rivet, because the joint is not tight, pot of water easy to sharply concentrated in these parts.
Close to its yield point in m e t al tensile stress.
The above three conditions, the lack of any one can not make the boiler produces caustic embrittlement.
   5. To prevent caustic embrittlement
Way to prevent boiler caustic embrittlement, besides changing the manufacturing process of the boiler (such as riveting and bilge GuanGaiCheng welding), and improve processing quality, such as to eliminate stress and cracks on the boiler installation), is from the chemical method to control the boiler water free alkali, eliminate the pan of water erosion.
青海华信锅炉有限公司|青海燃煤锅炉|青海燃气锅炉|青海锅炉公司|青海哪个品牌锅炉好