Stainless Steel Casting

Alloys of chromium and carbon that can be hardened by heat treatments and are ferromagnetic. They possess martensitic crystal structures in their hardened condition, although they’re less resistant to corrosion than other grades. The chromium content does not usually exceed 18%, while the carbon content might exceed 1.0%.

Martensitic stainless steels, such as types BS3146 PART 2 1975 ANC1A, B, C and ANC2, are similar in composition to the ferrite group, but contain a balance of C and Ni versus Cr and Mo; hence, austenite at high temperatures transforms to martensite at low temperatures.

Excess carbides may be present to enhance wear resistance or to maintain cutting edges, as is the case with knife blades. They’re commonly used for golf club heads and pump and valve parts as well.

UTS 500 – 1000N/mm2.  Elongation 8-15%.  HB 150-300

These alloys are ferromagnetic, ductile and typically contain less than 30% of chromium in their composition. They possess body-centred cubic (bcc) crystal structures.

This grade has good ductility and formability, but high-temperature mechanical properties are inferior to the austenitic stainless steels. The toughness of the grade is limited at low temperatures and in heavy sections.

Some ferritic stainless steels (such as types 409 and 405) are used, for example, in mufflers, exhaust systems, kitchen counters and sinks, as they are more cost-efficient than other stainless steels. Other more highly alloyed steels low in C and N (such as types 444 and 261) are costlier but are highly resistant to chlorides.

Incredibly easy to weld, austenitic stainless steels are nonmagnetic in the annealed condition and particularly strong at high temperatures. They have a face-centred cubic (FCC) structure. Austenite is formed by using austenitic elements like nickel, manganese and nitrogen.

Austenitic stainless steels are the most weldable of the stainless steels. They can be divided rather loosely into three groups: common chromium-nickel (300 series), manganese-chromium-nickel-nitrogen (200 series) and speciality alloys.

These alloys can be hardened only by cold working and might present some ferromagnetism due to this cold working or welding. They have good cryogenic properties as well, and chromium content varies between 16% to 26%; the nickel content is commonly below 35%. They are used in industries like chemical, pharmaceutical, firefighting, etc.

UTS 450 – 500N/mm2.  Elongation 10-12%.  HB 120

These alloys tend to have higher tensile and yield strength and great stress corrosion cracking resistance , which is better than austenitic alloys. They’re a mixture of bcc ferrite and fcc austenite crystal structures, although most tend to have equal amounts of these phases in the annealed condition.

Duplex stainless steels typically contain approximately 22-25% chromium and 5% nickel with molybdenum and nitrogen. Their main alloying elements are chromium and nickel, and they tend to have poor toughness compared to austenitic stainless steels

These alloys are made primarily from chromium and nickel and reach high strength by precipitation-hardening of their structure. In the annealed condition, they can be either austenitic or martensitic stainless steels. They’re typically used in the construction industry, where resistance to corrosion and high stress is required. They’re also used for surgical instruments and safety fall arrest equipment when working at height.

Precipitation-hardened stainless steels are grouped into three types: martensitic, semi-austenitic and austenitic. The martensitic (such as Type 630, 17-4ph and BS3146 PART 2 1975 ANC22) and semi-austenitic (such as Type 631) can provide higher strength than the austenitic (such as Type 660, also known as A286).

UTS 900 – 1300N/mm2.  Elongation 6-8%.  HB 270-380 (Approximate Range)