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STAINLESS STEEL

AUSTENITIC
STAINLESS
STEEL
TYPE 201 205 301 302 304/304L 309 316/316L 321
UNS S20100 S20500 S30100 S30200
S30215
S30400
S30403
S30900
S30908
S31600
S31603
S32100
FERRITIC
STAINLESS
STEEL
TYPE 405 409 429 430 434 436 442 444 439
UNS S40500 S40900 S42900 S43000
S43020
S43400 S43600 S44200 S44400 S43035
FERRITIC
STAINLESS
STEEL
TYPE 409M
INDIA IRSM 44
EN 10088-2-2005 X2CrNi12
MARTENSITIC
STAINLESS
STEEL
TYPE 403 410 414 416 420 422 431 440A/B/C
UNS S40300 S41000 S41400 S41600
S41623
S42000
S42020
S42200 S43100 S44002
S44003
S44004
PRECIPITATION
STAINLESS
STEEL
17-4 PH 17-7 PH TYPE 630 A-286 1.4542
Stainless steel is the name given to a family of corrosion and heat resistant steels containing a minimum of 10.5% chromium. Just as there is a range of structural and engineering carbon steels meeting different requirements of strength, weldability and toughness, so there is a wide range of stainless steels with progressively higher levels of corrosion resistance and strength. This results from the controlled addition of alloying elements, each offering specific attributes in respect of strength and ability to resist different environments. Stainless steels are in general grouped into:
  • martensitic stainless steels
  • ferritic stainless steels
  • austenitic stainless steels
  • duplex (ferritic-austenitic) stainless steels
  • precipitation-hardening stainless steels


Stainless steels are a iron-based alloy containing at between 10.5% to 30% Cr. Stainless steel achieve its stainless characteristic through the formation of an invisible and adherent chromium-rich oxide surface film.

Other alloying elements added to improve the characteristics of the stainless steel include nickel, molybdenum, copper, titanium, aluminum, silicon, niobium, nitrogen, sulphur, and selenium.

Selection of stainless steels are in general based on

  • corrosion resistance
  • fabrication characteristics
  • availability
  • mechanical properties for specific temperature ranges
  • product cost


AUSTENITIC STAINLESS STEEL: Austenitic, or nonmagnetic stainless steels, are classified in the 200 and 300 series, with 16% to 30% chromium and 2% to 20% nickel for enhanced surface quality, formability and increased corrosion and wear resistance, and are nonhardenable by heat treating. These steels are the most popular grades of stainless produced due to their excellent formability and corrosion resistance. All austenitic steels are nonmagnetic in the annealed condition. (Depending on the composition, mainly the nickel content, austenitics do become slightly magnetic when cold worked.) Austenitic stainless steel grades include: Type 201, NITRONIC� 30, 301, 304, 305, 309S, 316, 316L, and 321. Austenitics are used for automotive trim, cookware, food and beverage equipment, processing equipment, and a variety of industrial applications such as in chemical plants, power plants, food processing and dairy equipment. Austenitic stainless steels are the most weldable of the stainlesses and can be divided rather loosely into three groups: common chromium-nickel (300 series), manganese-chromium-nickel- nitrogen (200 series) and specialty alloys.

FERRITIC STAINLESS STEEL: Ferritic stainless steels are plain chromium stainless steels with a chromium content varying between 10.5 and 18% and a low carbon content. Ferritic stainless steel are magnetic and cannot be hardened by heat treatment and are always used in the annealed condition. Ferritic stainless steel consists of iron-chromium alloys with body-centered cubic crystal structures. They can have good ductility and formability, but high-temperature strengths are relatively poor when compared to austenitic grades. They are also not susceptible to stress corrosion cracking. Weldability is acceptable in thin sections but decreases as section thicknesses increase.

Ferritic, or nonhardenable stainless steels, are classified in the 400 series and are normally specified due to superior corrosion resistance and resistance to scaling at elevated temperatures. With inherent strength greater than carbon steels, ferritic provide an advantage in many applications where thinner materials and reduced weight are necessary, such as automotive emission control systems. Commercially available AISI grades are Type 409, Aluminized 409, 410S, 430, 434, 436, 439, Aluminized 439 and 444.

Some ferritic stainless steel (such as types 409 and 405) used, for example, in mufflers, exhaust systems, kitchen counters and sinks, cost less than other stainless steels. Other more highly alloyed steels low in C and N (such as types 444 and 261) are more costly but are highly resistant to chlorides. Ferritic stainless steel include grades like 430 and contain only chromium as a major alloying element. They are known for their moderate corrosion resistance and poor fabrication properties. Fabrication properties can be improved by alloy modifications and are satisfactory in grades such as 434 and 444.

MARTENSITIC STAINLESS STEEL: Martensitic, or hardenable stainless steels, are classified in the 400 series, usually with 11.5% chromium up to 18% chromium, with higher levels of carbon than ferritics, and are capable of being heat treated to a wide range of hardness and strength levels. Martensitic stainless steels work in the same way as many low alloy steels. Carbon is the key element. They have a structure similar to the ferritics with a 'body-centred tetragonal' (bct) crystal lattice. Normally, when steels are heated they transform from ferrite to austenite. On slow cooling the steel transforms back to ferrite. However, with fast cooling through quenching in water, oil or sometimes even air, the carbon atoms become trapped in a somewhat distorted atomic matrix. This is known as body-centred tetragonal. The distortion of the atomic matrix leads to the hard martensitic structure. The higher the carbon level the harder is the martensite. In the as- quenched condition, martensitic steels are virtually useless as they have insufficient impact toughness.

Due to the addition of carbon, they can be hardened and strengthened by heat treatment, in a similar way to carbon steels. They are classed as a "hard" ferro-magnetic group. In the annealed condition, they have tensile yield strengths of about 275 MPa and so they are usually machined, cold formed, or cold worked in this condition. The strength obtained by heat treatment depends on the carbon content of the alloy. Increasing the carbon content increases the strength and hardness potential but decreases ductility and toughness.

Commercially produced AISI grades of this class are Type 410, 410H, 420, and 420HC. Martensitic stainless steels are used extensively in cutlery, sport knives and multi- purpose tools. Martensitic stainless steels, such as types 403, 410, 410NiMo and 420, are similar in composition to the ferrite group, but contain a balance of C and Ni vs. Cr and Mo; hence, austenite at high temperatures transforms to martensite at low temperatures. Like ferrite, they also have a body-centered cubic crystal structure in the hardened condition. The carbon content of these hardenable steels affects forming and welding. To obtain useful properties and prevent cracking, the weldable martensitics usually require preheating and postweld heat treatment.

MAJOR GRADES OF MARTENSITIC STAINLESS STEEL:
  • 410-BASIC GRADE
  • 420-HIGHER HARDNESS GRADE
  • 431-HIGHER CORROSION RESISTANT AND TOUGHNESS GRADE
  • 440A/B/C-INCREASING HARDNESS AFTER HEAT TREATMENT
  • 416-WELDING CONSUMABLE GRADES
PRECIPITATION HARDENING STAINLESS STEEL: Precipitation-hardening stainless steels are chromium-nickel stainlesses, which contain alloying additions such as aluminum, copper or titanium that allow them to be hardened by a solution and that provide an optimum combination of the properties of martensitic and austenitic grades. Like martensitic grades, they develop their high strength and hardness through a variety of heat treatments and they also have the corrosion resistance of austenitic steel. Precipitation Hardening stainless steels, or hardenable chromium-nickel alloys, are classified as martensitic, semi-austenitic or austenitic in the aged condition. The martensitic (such as Type 630) and semiaustenitic (such as Type 631) can provide higher strength than the austenitic (such as Type 660, also known as A286).

They are used in aircraft parts and commonly viewed as bar alloys but are also available in flat roll products with a very high strength-to-weight ratio. The martensitic PH steels are used in aerospace, chemical and petrochemical, and food processing applications. Semi-austenitic grades are 17-7 PH� and PH 15-7 Mo�. They are austenitic in the annealed state, but martensitic in the hardened condition. Other grades of PH alloy stainless steels include 17-4 PH and 15-5 PH�. The most well known precipitation hardening steel is 17-4 PH. The name comes from the additions 17% Chromium and 4% Nickel. It also contains 4% Copper and 0.3% Niobium. 17-4 PH is also known as stainless steel grade 630.

The PH grades achieve high tensile properties in heat treated conditions. Applications for PH alloy steels include aerospace components, flat springs and retaining rings, among others. The advantage of precipitation hardening steels is that they can be supplied in a �solution treated� condition, which is readily machinable. After machining or another fabrication method, a single, low temperature heat treatment can be applied to increase the strength of the steel. This is known as ageing or age-hardening. As it is carried out at low temperature, the component undergoes no distortion.

 

PRODUCTS :

Corrosion Resistant Steel Plates | Sailma Grades Steel Plates & Sheets | Wear Plates As Per Hardox 400,

RAEX 400, JFE EH 360, FORA 400, XAR 400, DILLIDUR 400, 400 BHN Hardness Plates


Alloy Steel Plates / ASTM A 387-78 / Pressure Vessel Plates |EN10028 15MO3, 16MO3 , ASTM A 204 GRADE A ,

ASTM A 204 GRADE B , ASTM A 204 GRADE C


Boiler and Pressure Vessel Steel Plates | ASTM A36 , ASTM 283 GRADE A , ASTM 283 GRADE C , S27JR , S235JR ,

IS2062 GRADE A , IS2062 GRADE B , SS 400
| Stainless Steel Plates

Duplex / Super Duplex Steel | Inconel 625 (ALLOY 625 UNS N06625), Hastelloy C276 (ALLOY C276 UNS

N10276), Inconel 600 (Alloy 600 UNS N06600) , Inconel 825 (Alloy 825 UNS N08825), Inconel 800 (Alloy

800 UNS N08800), Monel 400 (Alloy 400 UNS N04400), Alloy 2


ASTM A 387 | ASTM 242 TYPE-1 | ASTM 588 GR.A | JIS G 3125 SPA H | IRSM 41-97 | IRSM 44 | S355J2W+N

Weathering Steel A | Boiler Quality Plates ASTM A 516 GR. 60/70 | High Tensile Plates As Per Weldox, Dillimax

690, S690QL , Naxtra 70 , Weldox , JFE 780LE , Hiten 780