Enamel Coating on Stainless Steel
Stainless steel can be also coated with enamel, for stainless steel with different chemical compositions and crystal structures, its enameling process and enamel frit used is also different. Experts from Nolifrit will introduce different types of stainless steel to you let you know how to choose enamel frit for stainless steel according to its types and chemical composition.
Stainless steel mainly divide into 200 series(Cr-Ni-Mn stainless steel), 300 series(Cr-Ni stainless steel) and 400 series(Cr stainless steel). The microstructure of 200 and 300 series stainless steel at room temperature is austenite, so they’re also called austenite stainless steel. The microstructure of 400 series stainless steel is ferrite(or martensite), so it’s called ferrite stainless steel or martensite stainless steel.
Ferrite stainless steel is magnetic, easy to enamel, with low firing temperature. Austenite stainless steel is not magnetic, with very high coefficient of expansion, special enamel frit must be applied to enamel it. And its firing temperature very high. Adherence will be weak with low temperature, as stainless steel inside is not fully oxidized.
Stainless steel is mainly made of Iron, Chrome and Nickel or Iron and Chrome. The contains of Chrome and Nickel varies a lot, from A few to a few dozen percent. With more Chrome and Nickel contained, the antioxidant ability of stainless steel in high temperature will improved, its firing temperature will also increase. The follow sheet is the chemical compositions of common stainless steel:
|
Series |
Code |
Chemical Compositions (unit: %) |
||||||||
|
C |
Cr |
Ni |
Mn |
P |
S |
Si |
N |
Mo |
||
|
201 |
1Cr17Mn6Ni5N |
≤0.15 |
16.00~18.00 |
3.50~7.50 |
5.50~7.50 |
≤0.060 |
≤0.030 |
≤1.00 |
≤0.25 |
-- |
|
204 |
03Cr16Mn8Ni2N |
≤0.03 |
15.00~17.00 |
1.50~3.50 |
7.00~9.00 |
-- |
-- |
≤1.00 |
≤0.25 |
-- |
|
304 |
0Cr18Ni9 |
≤0.07 |
17.00~19.00 |
8.00~10.00 |
≤2.00 |
≤0.035 |
≤0.030 |
≤1.00 |
-- |
-- |
|
304L |
00Cr19Ni10 |
≤0.030 |
18.00~20.00 |
8.00~10.00 |
≤2.00 |
≤0.035 |
≤0.030 |
≤1.00 |
-- |
-- |
|
316 |
0Cr17Ni12Mo2 |
≤0.08 |
16.00~18.50 |
10.00~14.00 |
≤2.00 |
≤0.035 |
≤0.030 |
≤1.00 |
-- |
2.00~3.00 |
|
316L |
00Cr17NI14Mo2 |
≤0.030 |
16.00~18.00 |
12.00~15.00 |
≤2.00 |
≤0.035 |
≤0.030 |
≤1.00 |
-- |
2.00~3.00 |
|
430 |
1Cr17 |
≤0.12 |
16.00~18.00 |
-- |
≤1.00 |
≤0.035 |
≤0.030 |
≤0.75 |
-- |
-- |
|
447J1 |
00Cr30Mo2 |
≤0.010 |
28.50~32.00 |
-- |
≤0.40 |
≤0.035 |
≤0.030 |
≤0.40 |
≤0.015 |
1.50~2.50 |
Nowadays, 200,201 series and 304, 316 in 300 series is most common used in domestic market. For enameling of those stainless steels, special enamel frit or even industrial enamel frit is needed, in order to get the strong adherence. This also depends on the shape of products. For example, product in small size, with little demand on impact resistance, can be directly coated with cover coat. The following picture is the stainless steel sign of one of our customers.
For the product with strict demand on impact resistance. Stainless steel need to be sand blasted before enameling, to make stainless steel with rough surface. And special enamel frit is used for this. Firing temperature should be higher than 900℃. This is better for the full oxidation of stainless steel substrate, also good to let enamel layer permeate into stainless steel, to form strong adherence. As there’re Cobalt oxide and Nickel oxide in ground coat, so the color of single ground coat is blue or black. If you want to get other colors, cover coat will be needed for second coating. The following picture is the enamel stainless steel door handle of our customer. The material used is 304 stainless steel, the surface is coated by our Titanium lake blue cover coat.
Enamel on stainless steel from Hunan Noli Enamel Co., Ltd is high temperature resistant, corrosion resistant, can avoid oxidation of substrate in high temperature. It mainly applied in high temperature mechanical and corrosion resistant parts. And stainless steel enamel cookware etc… Nolifrit believe that stainless steel with enamel coating is of very nice performance and will be applied in more and more field.