1. Compared with 304 stainless steel, the advantages of duplex stainless steel are as follows:
(1) the yield strength of austenitic stainless steel is twice higher than that of ordinary austenitic stainless steel, and it has enough plastic toughness for forming. The wall thickness of the tank or pressure vessel made of duplex stainless steel is 30-50% less than that of austenite, which is helpful to reduce the cost.
(2) it has excellent resistance to stress corrosion cracking. Even the duplex stainless steel with the lowest alloy content has higher resistance to stress corrosion cracking than the austenitic stainless steel, especially in the environment containing chloride ions. Stress corrosion is an outstanding problem that is difficult to solve for ordinary austenitic stainless steel.
(3) the corrosion resistance of 2205 duplex stainless steel, which is widely used in many media, is better than 316L austenitic stainless steel, while the super duplex stainless steel has very high corrosion resistance. In some media, such as acetic acid, formic acid, etc., it can even replace high alloy austenitic stainless steel and even corrosion-resistant alloy.
(4) it has good local corrosion resistance. Compared with austenitic stainless steel with the same alloy content, its wear resistance and fatigue corrosion resistance are better than austenitic stainless steel.
(5) compared with austenitic stainless steel, the coefficient of linear expansion is lower, close to carbon steel, suitable for connection with carbon steel, which has important engineering significance, such as production of composite plate or lining, etc.
(6) no matter under the condition of dynamic or static load, it has higher energy absorption capacity than austenitic stainless steel, which has obvious advantages in dealing with sudden accidents such as collision, explosion, etc., and has practical application value.
2.About SS 304.
Grade 304 is a standard "18/8" stainless. It is the most versatile and most widely used stainless steel available, even though a wide range of alternatives are available; and has excellent forming and welding characteristics. The balanced austenitic structure of Grade 304 enables it to be severely deep drawn without intermediate annealing. This means that this grade steel is dominant in the manufacture of drawn stainless parts such as sinks, hollow-ware and saucepans. For these applications, it is common to use special "304DDQ" (Deep Drawing Quality) variants. Grade 304 can be readily braked or roll-formed into a variety of components for applications in the industrial, architectural, and transportation fields. It also has outstanding welding characteristics. Post-weld annealing is not required when welding thin sections.
Composition:
Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N | |
304 | min. | - | - | - | - | - | 18 | - | 8 | - |
max. | 0.08 | 2 | 0.75 | 0.045 | 0.03 | 20 | 10.5 | 0.1 | ||
304L | min. | - | - | - | - | - | 18 | - | 8 | - |
max. | 0.03 | 2 | 0.75 | 0.045 | 0.03 | 20 | 12 | 0.1 | ||
304H | min. | 0.04 | - | - | -0.045 | - | 18 | - | 8 | - |
max. | 0.1 | 2 | 0.75 | 0.03 | 20 | 10.5 |
Mechanical Properties:
Grade | Tensile Strength (MPa) min | Yield Strength 0.2% Proof (MPa) min | Elongation (% in 50 mm) min | Hardness | |
Rockwell B (HR B) max | Brinell (HB) max | ||||
304 | 515 | 205 | 40 | 92 | 201 |
304L | 485 | 170 | 40 | 92 | 201 |
304H | 515 | 205 | 40 | 92 | 201 |
Physical Properties:
Grade | Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (μm/m/°C) | Thermal Conductivity (W/m.K) | Specific Heat 0-100 °C (J/kg.K) | Electrical Resistivity (nΩ.m) | |||
0-100 °C | 0-315 °C | 0-538 °C | at 100 °C | at 500 °C | |||||
304/L/H | 8000 | 193 | 17.2 | 17.8 | 18.4 | 16.2 | 21.5 | 500 | 720 |
4.Packaging and transportation: