What is stainless steel?

We often say the material of stainless steel investment castings is SS304,SS316,ect.So what is stainless steel?

Stainless Steel is short for acid-proof Stainless Steel, resistant to weak corrosive medium such as air,steam,water,or a steel with rustless property.According to its organizational structure,stainless steel  is divided into austenite stainless steel,ferritic stainless steel,duplex stainless steel,martensiticstainless steel and precipitation hardening stainless steel.

1.Austenitic stainless steel

Austenite size stainless steel is the most important type of stainless steel, taking amount of 70% of the total output and consumption of stainless steel. 

According to the way of alloying,austenite size stainless steel can be divided into nickel chrome steel and iron chromium manganese steel.The former is using nickel as austenitic steel,is the main body of austenitic steel;The latter is steel grade mainly with the manganese, nitrogen instead of the expensive nickel.

Overall speaking, the corrosion resistance of austenitic steel is good, which has the good comprehensive mechanical properties and process performance, but the strength and hardness is low.

2.Ferritic stainless steel

Ferritic stainless steel contains chromium 11%-30%, basic does not contain nickel,in the condition of using,the organizational structure is given priority to with ferrite.

Ferritic stainless steel,is high strength,and lower cold hardening tendency, resistance to chloride stress corrosion,pit corrosion,crevice corrosion and local corrosion performance is good, but is sensitive to intergranular corrosion, poor toughness at low temperature.

3.Duplex stainless steel

It is generally believed that there is more than 15% on austenitic matrix of ferrite, or on the ferrite matrix is more than 15% of the austenite,duplex stainless steel can be called austenite plus ferrite.Duplex stainless steel has the advantages of both austenitic steel and ferritic steel.

4.Martensitic stainless steel

Martensitic stainless steel is a kind steel adjusting its performance by means of heat treatment, its strength and hardness is high.

5.PH stainless steel

Precipitation hardening stainless steel is a steel precipatating out cardide from steel by means of heat treatment, so as to achieve the goal of improving strength of steel.

Main characteristics of stainless steel:

*Weldability
*Corrosion resistance
*Polishing performance
*Heat resistance