Stainless Steel 304 and 304L Used for Vavles

Stainless Steel 304 and 304L Used for Vavles


1. What is stainless steel?
Stainless steel is a type of steel. Steel refers to steel containing less than 2% of carbon, and steel with a carbon contect of more than 2% is iron. The addition of chromium (Cr), nickel (Ni), manganese (Mn), silicon (Si), titanium (Ti), molybdenum (Mo) and other alloying elements in the smelting process improves the properties of the steel and makes the steel more resistant to corrosion, this is, what we often call stainless steel.
 
What exactly are steel and iron? 
What are the characteristics of steel and iron? What is the relationship between them? What are stainless steel 304, 304L, 316, and 316L and their differences? Steel is a material with iron as the main element, with carbon content generally below 2%, and other elements according to GB/T 13304-91 "Classifications of Steel". Iron is a metallic element with the atomic number 26. Iron has good ferromagnetism, good plasticity and thermal conductivity. Stainless steel is resistant to weak corrosive media such as air, steam, and water. The commonly used steel grades are 304, 304L, 316, 316L, which are 300 series of austenitic stainless steels.
 
2. Why does stainless steel have different steel grades?
In the smelting process of stainless steel, due to the different varieties of alloying elements added, their characteristics are also different. In order to distinguish between them, they are entitled to different steel grades. The following is a table of alloying element content of different steel grades of common decorative stainless steel for reference only.
 
Chemical composition (mass fraction, %)
Grades Carbon Silicon Manganese Phosphorus Sulfur Chromium Nickel
304 Less than and equal to 0.08 Less than and equal to 1.00 Less than and equal to 2.00 Less than and equal to 0.045 Less than and equal to 0.03 18 to 20 8 to 10
301 Less than and equal to 0.15 Less than and equal to 1.00 Less than and equal to 2.00 Less than and equal to 0.045 Less than and equal to 0.03 16 to 18 6 to 8
202 Less than and equal to 0.15 Less than and equal to 1.00 7.5 to 10 Less than and equal to 0.05 Less than and equal to 0.03 17 to 19 4 to 6
201 Less than and equal to 0.15 Less than and equal to 1.00 5.5 to 7.5 Less than and equal to 0.05 Less than and equal to 0.03 16 to 18 3.5 to 5.5
 
Stainless steel 304
Performance of stainless steel 304

304 stainless steel is the most common type of steel. As a widely used steel, it has good corrosion resistance, heat resistance, low-temperature strength and mechanical properties, good hot workability such as stamping, bending, and no heat treatment hardening. The operating temperature is between -196℃ and 800℃.
 
Applications of stainless steel 304
Stainless steel 304 is used for boilers, indoor pipes, building materials, chemicals, valves in the food industry, agriculture and ship parts.
 
Performance of stainless steel 304L
As a low-carbon 304 steel, its corrosion resistance is similar to that of 304 steel under normal conditions, but after welding or stress relief, its resistance to grain boundary corrosion is excellent. It can also remain good corrosion resistance without heat treatment. The operating temperature is between -196℃ and 800℃.
 
Applications of stainless steel 304L
Stainless steel 304L is used in field open-air machines in chemical, coal and petroleum industries that require good resistance to grain boundary corrosion, building materials and parts with difficult heat treatment.