FIFTEEN POINTS OF STAINLESS STEEL


1. Stainless Steel is an alloy of iron and chromium with minimum 10.5 percent.
2. Chromium produces a thin layer of oxide on the surface of steel called as "passive layer". This prevents corrosion.
3. for other useful properties it also contains carbon, silicon, manganese, nikel, molybdenum.
4. stainless steel was discovered in 1913 sheffield metallurgist Harry Brearley.
5. Types of corrosion in stainless steel: Pitting Corrosion, Crevice Corrosion, General Corrosion, Stress Corrosion Cracking (SCC), Intergranular Corrosion, Galvanic Corrosion

 pitting Corrosion due to chlorine ion like in salt and bleach. to avoid it have to use high resistance steel to corrosion.
Crevice corrosion is due to lack of oxygen on the passive layer. For this use flexible sealant or high corrosion resistant grade.
General Corrosion due to certain concentrated hydrochloric Acid, Sulphuric Acid.
Stress Corrosion Cracking (SCC): This corrosion normally happens in hot water tank and swimming pool. it requires very specific combination of tensile stress, temperature, and corrosion species. like Sulphide. (SSCC). Its Solution is Ferritic
Intergranular Corrosion: This corrosion happens in high carbon steel. when at the temp of 450 to 850 degree Celsius Chromium interact with carbon to make Chromium Carbide. To avoid use steel of low content carbon or use containing Titanium or Niobium.
Galvanic Corrosion: It can occur by contacting with other metal and by contact with electrolyte like water or other solution. It can be avoid by use an metal insulator like rubber.

 6.there are 5 types of stainless steel. Ferritic, Austenitic, Martensitic, Duplex, Percipitaion Hardening (PH)
 Ferritic: These steels are chromium contains <.10% these have similar micro-structure to carbon to low alloy steel.
It has lack of toughness in welding., It can't be hardened by heat treatment.They are magnetic.
use for stress corrosion cracking.
 Austenitic: These micro-structure derived from the addition of Nickel, Manganese, and Nitrogen. Its normally non-magnetic.
Martensitic:  It has high carbon as much as 1%.It has low weldibility and hardening properties. It is magnetic.
Duplex: it has micro-structure which has 50% ferritic and 50% austenitic.
Percipitation Hardening(PH): These steels can develop very high strength by adding elements copper, nobium and aluminium.

 7. SS is theoretically non-magnetic but in practice it is magnetic (permeability 1.1).
8. Duplex are used to make storage tank, Precipitation-hardening to make long shaft.
 9. Some variety of stainless steel can goes upto 1100 degree Celsius.
10. There are different type of finishes of stainless steels like polished, brushed, blasted, etched and colored finishes.
11.  Austenitic are weldable than the other types. Ferritic are weldable in thin section.
12. we see Austenitic steel in form of all product over a wide range of dimension, housewares, industrial piping, and vessels, construction,architectural facades. ferritic in form of sheet, washing machine, boilers, automotive exhaust systems,dishwashers and indoor architecture. and Martensitic in form of bar, knives, fasteners, surgical equipment and turbine blades.Duplex are normally used in paper, pulp, shipbuilding and petrochemical industries.
13. By two technologies elemental analysis can be done 1.X-Ray Fluorescence (XRF). 2. Optical Emission Spectroscopy(OES)
14. pickling and passivation are two process for maintenance of stainless steel.
15. the stainless steel stocks normally includes coil, sheet, plate,bar, wire, pipe, tube, safety flooring products, reinforcing bars, fasteners, mesh. 

Comments

  1. Unknown15 January 2019 at 11:15

    I have no idea buddy! :)

    ReplyDelete
    Replies
    1. SOURAV SWAIN10 February 2019 at 07:54

      it is not hard to knoow. you can get a over all idea regarding SS Steel.

      Delete

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