304 stainless steel VS 403 stainless steel
Grades 304 and 430 are commonly used stainless steel materials. 304 stainless steel is a general type of chromium-nickel austenitic stainless steel, the density of 7.93 g/cm3, also known as 18/8 stainless steel, is 300 series of stainless steel is the most commonly used steel. It can withstand high temperature 800℃, has good processing performance and toughness, widely used in the requirements of good comprehensive performance (corrosion resistance and molding) equipment and parts. 304L is a low-carbon version of 304, which does not require post-weld annealing, so it is widely used for thick gauge parts (approx. 5mm and above). The higher carbon content of 304H can be used at high temperatures. The annealed austenite structure also gives these grades excellent toughness, even at low freezing temperatures.
Low carbon high chromium 430 is one of the most common ferritic stainless steels, has good corrosion resistance, also known as 18/0 or 18-0, is one of the 400 series of stainless steels. It can be made slightly strengthened by cold working, but the low-temperature toughness is poor, and generally can not be hardened by heat treatment. Its thermal conductivity is better than austenite, the coefficient of thermal expansion is smaller than austenite, heat resistance fatigue, the addition of stabilizing element titanium makes the welding seam part of the mechanical property is good, can be used for building decoration, fuel burner parts, household appliances, household appliances parts. 430F is a kind of steel with free cutting performance on 430 steel, mainly used for automatic lathes, bolts and nuts, etc. 430LX adds Ti or Nb in 430 steel, reduces the content of C, and improves the processing performance and welding performance. It is mainly used for hot water tanks, heating water systems, sanitary appliances, household durable appliances, bicycle flywheels, etc.
According to ASTM A240- Specifications for chromium and chromium-nickel stainless steel plates, sheets and strips for pressure vessels and general purposes, 430 stainless steel shall contain less than 0.12% carbon, between 16-18% chromium, and less than 0.75% nickel, the difference between 304 and 430 as shown in the table below:
Chemical composition comparison
| UNS | C | Mn | P | S | Si | Cr | Ni | Mo |
| S30400 | 0.07 | 2.00 | 0.045 | 0.03 | 0.75 | 17.5-19.5 | 8.0-10.5 | / |
| S43000 | 0.12 | 1,00 | 0.04 | 0.03 | 1.00 | 16.0-18.0 | 0.75 | / |
Mechanical property comparison
| Grades | Yield strength, Mpa | Tensile strength, Mpa | Elongation in 2 /50mm, min, % | Hardness, HBW |
| 304 | 205 | 515 | 40 | 183 |
| 403 | 205 | 450 | 22 | 201 |
To sum up, they differ mainly in the following items:
- Corrosion resistance: The corrosion resistance of 304 stainless steel is better than 430. Because 430 stainless steel contains 16.00-18.00% chromium, basically does not contain nickel, 304 stainless steel contains more chromium and nickel;
- Stability: 430 stainless steel is ferrite form, 304 stainless steel is austenite, more stable than 430 stainless steel;
- Toughness: The toughness of 304 is higher than 430 stainless steel;
- Thermal conductivity: The thermal conductivity of ferrite 430 stainless steel is like 304 stainless steel;
- Mechanical properties: 430 stainless steel welding seam mechanical properties than 304 stainless steel is better because of the addition of stable chemical element titanium.
