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Austenitic SS 310

Austenitic SS 310

The austenitic 310 is a medium-carbon austenitic stainless steel with excellent heat resistance, making it the best fit for high temperature applications: furnace parts, heat treatment equipment, etc.

Austenitic SS 310 grade contains about 25% chromium and 20% nickel. The composition provides the required resistance to corrosion and extra toughness to the material, which other grades are unable to provide at room temperature. This makes the grade applicable in sulphur-reducing atmospheres, which contain hydrogen sulphide.

Tough with low magnetic permeability, SS 310 is used in cryogenic applications – cryogenic fuels for rockets to cryogenic gases used to transport frozen food. SS 310 suffers from thermal shock if used frequently for liquid quenching.

Creep resistance is important for an alloy to be used at elevated temperatures. In thousand-hour usage at 600°C, small creeps extend and get ruptured at about 200 MPa. SS 310 has 0.1% carbon content which is higher than other grades, increasing creep properties of the alloy.

UNS 31000 (SS 310) has good resistance to sulfidation and other forms of hot corrosion, called Type 304/304L. SS 310 alloy can be readily cold formed by standard methods and equipment with machinability is similar type 304. Work hardening may pose problematic, and removal of the work hardened layer is executed by using slow speeds, heavy cuts, with sharp tools, powerful machines and good lubrication.

SS 310 resists oxidation at temperatures up to 2000 ̊F in dry air. It forms a tireless scale at high temperature and is resistant to spalling and performs superior to Type 309 in thermal cycling applications.

Alloy 310 finds usage in cryogenic applications with low magnetic permeability and toughness down to -450°F (-268°C). When heated between 1202°–1742°F (650°–950°C) the alloy is subject to sigma phase precipitation. A solution annealing treatment at 2012°–2102°F (1100°–1150°C) will restore a degree of toughness.

Known as Austenitic SS 310S grade and used in the chemical processing industry, it is the low carbon (0.04%) version of the Austenitic 310 stainless steel grade. In petrochemical environments, grade 310S is moderately used in carburizing atmospheres.

SS 310S is neither applied in high ductility nor is it suitable in high temperatures because of the carbon content and low melting point. This causes carbide precipitation in the grain structure.  The creep resistance enables the alloy to be used under thermal cyclic applications.

The grade’s grain structure will not harden with heat. Cold working method increases hardness albeit decreases strength. If internal stresses are to be removed, the alloy needs to be annealed perfectly. Grade 310S is less prone to embrittlement and sensitisation in service. Its composition makes these steels capable for applications in reducing sulphur atmospheres containing H2S.

Excellent resistors to oxidation under mildly cyclic conditions, Stainless steels 310/310S undergo fabrication and can be forged in the range 975°-1175°C. Heavy work is carried out to 1050°C and a light finish is applied to the bottom of the range.

Grades 310/310S resist oxidation in intermittent service in air upto 1035°C and 1050°C in continuous service. The grades are resistant to oxidation, sulphidation and carburisation. Alloy 310 can be utilized in slightly oxidizing, nitriding, cementing and thermal cycling applications, even if the maximum service temperature must be reduced.

APPLICATIONS:

  • Austenitic SS 310 grade and Austenitic SS 310S grade are used in Fluidized bed combustors,
  • Kilns
  • radiant tubes
  • Tube hangers for petroleum refining and steam boilers
  • Coal gasifier internal components
  • Lead pots
  • Thermometric wells
  • Refractory anchor bolts
  • Burners and combustion chambers
  • Retorts and muffles
  • Annealing covers
  • Saggers
  • Food processing equipment
  • Cryogenic structures
  • High temperature containers
  • Oil burner parts
  • Welding filler wire and electrodes
  • Coal gasifier components
  • Fire box sheets