Moly ferritic stainless steels are chromium stainless steels alloyed with Molybdenum, and can be stabilised with niobium and/or titanium.

Annealed moly ferritics are ductile and can be formed using a large variety of roll forming or mild stretch bending operations as well as the more common drawing and bending operations. They do not harden excessively during cold working.

Being ferritic, they are not susceptible to stress corrosion cracking.

The steels have limited weldability and should not be used in the as-welded condition for dynamic or impact loaded structures. Moly ferritics can undergo grain growth in the heat affected zone of weldments, which may adversely affect the mechanical properties in these zones.

Applications involving welded moly ferritics are thus generally limited to a maximum thickness of 2.5mm. Edge welds are not recommended for applications using moly ferritics.

They are unsuited for use in cryogenic applications as brittle fracture could occur at sub-zero temperatures.

U-434 is a low carbon, molybdenum containing ferritic stainless steel. With 16% chromium and 1% molybdenum, the steel has better corrosion resistance than U-430. U-434 has excellent polishing characteristics and is therefore used in applications such as automotive trim.

U-434 also has good formability and corrosion resistance and this makes it suitable for applications such as dishwashers, kitchen-ware and restaurant equipment, architectural applications (except in coastal environments), nitric acid plant equipment, etc.

U-436 is a low carbon, niobium stabilised, molybdenum containing ferritic stainless steel. With 16% chromium and 1% molybdenum, the steel has better corrosion resistance than U-1.4509.

Niobium stabilisation improves the steel's resistance to sensitisation in the weld heat affected zone and improves the steel's creep resistance at high temperatures. U-436 has similar formability to U-1.4509 and is used in applications such as automotive exhaust systems and trim, cladding, domestic appliances, etc.

U-444 is a low carbon, dual stabilised, molybde - num containing ferritic stainless steel. With 18% chromium and 2% molybdenum, the steel has good pitting resistance and crevice corro - sion resistance, similar to U-316L.

U-444 is thus suitable for roofing and cladding in marine environments, as well as hot water tanks and geysers, heat exchanger tubing and food processing equipment.