ASTM A312 is a stainless steel piping specification that encompasses seamless, welded, and cold worked austenitic stainless steels. Featuring a low carbon content, these particular steels are highly weldable via all fusion and resistance welding processes. Such weldability renders them ideal for corrosive environments seen in industries such as chemicals, textiles, food and beverage, and pharmaceuticals. With a higher corrosion resistance compared to higher carbon ferritic and martensitic stainless steels, ASTM A312 austenitic stainless steels are a reliable choice.
Austenitic stainless steels are categorised into the 200 and 300 series, depending on the amount of chromium (16-30% for 200 and 18-30% for 300) and nickel (2-20% for 200 series and 8-22% for 300). These steels cannot be hardened by heat treatment as they remain austenitic even when subjected to extreme temperatures. Moreover, they are non-magnetic in their natural state but might become faintly magnetic after undergoing cold treatments.
Austenitic stainless steels stand out amongst the high-alloy varieties due to their impressive ductility, low yield stress, weldability, and key elements of chromium and nickel. Whether using fusion or resistance welding processes, these steels are renowned for their ability to be welded with ease.
Type 304 Stainless Steel is the most well-known austenitic variety – an alloy containing 18% chromium and 8% nickel that has non-magnetic properties in its annealed state. However, when the material is cold-worked, it may become slightly magnetized. Type 304L is an ultra-low carbon variation of Type 304 that can be used in welding without needing post-weld heat treatment.
Introducing Type 316 stainless steel – a highly resilient and dependable metal alloy composed of 16% chromium, 10% nickel, and 2% molybdenum. Past the ordinary Type 304, this specific material is known for its improved corrosion resistance thanks to the incorporated molybdenum. Though it lacks magnetic properties in its natural state, it may develop a slight magnetism once subjected to cold working.
Laced with titanium, Type 321 stainless steel is an austenitic alloy composed of 18% chromium and 8% nickel. It is far more resistant to intergranular corrosion than Type 304 stainless steel, and when left in the annealed condition will remain non-magnetic. If this alloy is worked cold, however, it may take on slightly magnetic properties.
With its high chromium and nickel content, Type 347 stainless steel is a stabilized austenitic variety with superior resistance to intergranular corrosion when compared to Type 304. Not to be fooled by its magnetic properties when cold worked, Type 347 remains non-magnetic in the annealed condition. Columbium and tantalum present an extra safeguard against corrosion for this already robust stainless steel.
Post time: 2023-06-20