I believe you are not unfamiliar with stainless steel, because there are many electrical appliances in our daily life.
Take the commonly used electric kettle as an example.
Careful netizens may find that there are a group of numbers on the inner wall of the electric kettle, some are 304 and some are 316.
So what does this group of numbers represent and what is the difference?
Today I will talk about the mystery.
See also:
304 and 316 are a code of stainless steel. They are all stainless steel in nature, but they are different types when subdivided.
Let’s take a look at the chemical composition, physical properties, mechanical properties, national brands, characteristics and uses of these two stainless steel.
Comparison of chemical compositions of 304 and 316 stainless steel
| Chemical composition: | 304 | 316 |
| C (carbon) | ≤0.08 | ≤0.08 |
| Si (silicon) | ≤1.00 | ≤1.00 |
| Mn (manganese) | ≤2.00 | ≤2.00 |
| P (phosphorus) | ≤0.045 | ≤0.045 |
| S (sulfur) | ≤0.030 | ≤0.030 |
| N (nickel) | 8.00~11.00 | 10.00~14.00 |
| Cr (chromium) | 18.00~20.00 | 16.00~18.00 |
| Mo (aluminum) | 2.00~3.00 |
Comparison of physical properties of 304 and 316 stainless steel
|
Physical performance parameters |
304 |
316 |
|
|
Density / (kg / dm3) 20 ℃ |
7.93 |
8.00 |
|
|
Baking point / ℃ |
1398-1454 |
1370-1397 |
|
|
Specific heat capacity / [kJ / (kg · K)] 0 ℃ ~ 100 ℃ |
0.50 |
0.50 |
|
|
Thermal conductivity / [w / (m·k)] |
100℃ |
16.3 |
16.3 |
|
500℃ |
21.5 |
21.5 |
|
|
Linear expansion coefficient / (10–6 / k) |
0℃~100℃ |
17.2 |
16.0 |
|
0℃-500℃ |
18.4 |
18.5 |
|
|
Resistivity / (Ω · mm2 / M) 20 ℃ |
0.73 |
0.74 |
|
|
Longitudinal elastic model / (KN / mm2) 20 ℃ |
193 |
193 |
|
|
Magnetic |
nothing |
nothing |
|
Comparison of 304 and 316 stainless steel grades in different countries
|
Comparison of stainless steel grades of various countries: |
304 |
316 |
|
|
China GB / T20878-2007 |
Uniform numerical code |
S30408 |
S31608 |
|
New brand |
06Cr9Ni10 |
06Cr17Ni12Mo2 |
|
|
Old brand |
0Cr18Ni9 |
0Cr17Ni12Mo2 |
|
|
America ASTM A959-04 |
S30400 304 |
S31600 316 |
|
|
Japan JIS G4303-1998 JIS G4311-1991 |
SUS304 |
SUS316 |
|
|
International IS0 / TS 15510:2003 ISO4955:2005 |
X5CrNi18-10 1.4301 |
X5CrNiMo17-12-2 1.4401 |
|
|
European EN 10088:1-1995, EN10095-1999, etc |
X5CrNi18-10 1.4301 |
X5CrNiMo17-12-2 1.4401 |
|
Note:
The chemical composition, physical performance parameters and comparison of stainless steel grades in various countries are all from the national standard stainless steel and heat-resistant steel grades and chemical compositions (GB / T 20878-2007).
Comparison of mechanical properties of 304 and 316 after solid solution treatment
|
Mechanical properties after solution treatment |
304 |
316 |
|
|
Specified plastic extension strength Rp0.2/MPa |
≥205 |
≥205 |
|
|
Tensile strength Rm / MPa |
≥515 |
≥515 |
|
|
Elongation after fracture A /% |
≥40 |
≥40 |
|
|
Hardness value |
HBW |
≤201 |
≤217 |
|
HRB |
≤92 |
≤95 |
|
|
HV |
≤210 |
≤220 |
|
Comparison of mechanical properties of 304 and 316H 1/4 states
|
Mechanical properties in H 1/2 state |
304 |
316 |
|
|
Specified plastic extension strength Rp0.2/MPa |
≥515 |
≥515 |
|
|
Tensile strength Rm / MPa |
≥860 |
≥860 |
|
|
Elongation after fracture A /% |
Thickness < 0.4mm |
≥10 |
≥10 |
|
Thickness: 0.4mm ~ < 0.8mm |
≥10 |
≥10 |
|
|
Thickness ≥ 0.8mm |
≥12 |
≥10 |
|
Comparison of mechanical properties of 304 and 316H 1/2 states
|
Mechanical properties in H 1/2 State |
304 |
316 |
|
|
Specified plastic extension strength Rp0.2/MPa |
≥760 |
≥760 |
|
|
Tensile strength Rm / MPa |
≥1035 |
≥1035 |
|
|
Elongation after fracture A /% |
Thickness < 0.4mm |
≥6 |
≥6 |
|
Thickness: 0.4mm ~ < 0.8mm |
≥7 |
≥7 |
|
|
Thickness ≥ 0.8mm |
≥7 |
≥7 |
|
Characteristics and uses
304 stainless steel is the most widely used stainless and heat-resistant steel, which is used in food equipment, general chemical equipment, atomic energy industry and so on.
316 stainless steel has better corrosion resistance than 06Cr19Ni0 in seawater and other media. It is mainly used for pitting resistant materials.
Heat treatment schedule
The heat treatment systems of 304 stainless steel and 316 stainless steel are the same.
The heat treatment temperature and cooling method are ≥ 1040 ℃, water cooling or other rapid cooling.
Note: the three mechanical property tables of solid solution treatment, H1 / 4 and H1 / 2, as well as the characteristics, uses and heat treatment system, are all from the national standard cold rolled stainless steel plate and strip GB / T 3280-2015.
Difference between 304 and 316
The biggest difference between 304 stainless steel and 316 stainless steel lies in the market application.
The price of 304 stainless steel is slightly lower than that of 316 stainless steel, which is widely used, such as kitchen utensils and tableware, building decoration, food industry, agriculture, ship parts, sanitary ware, automobile parts, etc.
Although a small part of 316 stainless steel is used in daily life, most of it is still used for equipment in seawater and production equipment with strong corrosion resistance.
The reason is that the addition of 2-3% molybdenum content consolidates the structure of 316 stainless steel, making it more wear-resistant and anti-oxidation, and at the same time, the corrosion resistance is greatly increased.
The difference between 304 and 316 stainless steel materials
Application:
304 stainless steel is mainly used for corrosion-resistant containers, tableware, furniture, railings and medical equipment. 316 stainless steel is mainly used in the food industry, watch accessories, pharmaceutical industry and surgical equipment.
Chloride corrosion resistance:
304 stainless steel is non-magnetic, and its metallographic structure cannot be changed by heat treatment.
316 stainless steel has a special corrosion-resistant structure due to the addition of molybdenum element, and has stronger chloride corrosion resistance.
It is also used as “marine steel”.
Extension:
- 316 stainless steel is austenitic stainless steel. Due to the addition of the Mo element, the corrosion resistance and high-temperature strength are greatly improved. High-temperature resistance can reach 1200-1300 degrees, and can be used under harsh conditions.
- 304 stainless steel is a common material in stainless steel, with a density of 7.93 g/cm3. It is also called 18/8 stainless steel in the industry. It can withstand the high temperature of 800 ℃, has good processing performance and high toughness, and is widely used in industry, furniture decoration industry and food and medical industry.
- Stainless steel is the abbreviation of stainless and acid-resistant steel. The steel resistant to air, steam, water and other weak corrosive media or with rust resistance is called stainless steel; and the steel resistant to chemical corrosion medium (acid, alkali, salt and other chemical etching) is called acid-resistant steel.
- Stainless steel itself has good corrosion resistance, and can still maintain its excellent physical and mechanical properties at high temperatures. It is also widely used in the field of 3D printing.
