Skip Navigation

Stainless Steel 347 - 1.4550

This data sheet applies for hot and cold rolled sheet, strip and bars, semi-finished products, rods and sections as well as for seamless and welded steel tubes for mechanical and general engineering purposes.

Application

For construction parts which should be resistant to scaling up to about 1050°C and extensively inured to the effect of sulfurous gases, especially above 900°C, is very low.

Chemical Compositions*

Element % Present (in product form)
Carbon (C) 0.08
Silicon (Si) 1.00
Manganese (Mn) 2.00
Phosphorous (P) 0.045
Sulfur (S) 0.015
Chromium (Cr) 17.00 - 19.00
Nickel (Ni) 9.00 - 12.00
Niobium (Nb) 10xC to 1.00
Iron (Fe) Balance
* Maximum values unless otherwise stated

Mechanical properties (at room temperature in annealed condition)

Product Form
C H P L L TW / TS
Thickness (mm) Max 8 13.5 75 160 2502) 60
Yield Strength Rp0.2 N/mm2 2203) 2003) 2003) 2054) 2056) 2055)
Rp1.0 N/mm2 2503) 2403) 2403) 2404) 2406) 2405)
Tensile Strength Rm N/mm2 520 - 7203) 520 - 7203) 500 - 7003) 510 - 7404) 510 - 7406) 510 - 7405)
Elongation min. in & A1) %min (longitudinal) - - - 40 - 35
A1) %min (transverse) 40 40 40 - 30 30
Impact Energy (ISO-V) ≥ 10mm thick Jmin (longitudinal) - 100 100 100 - 100
Jmin (transverse) - 60 60 - 60 60
1) Gauge length and thickness according to DIN EN.
2) ˃ 160mm
3) Transverse test piece, with product widths ˂ 300mm long. test piece.
4) Longitudinal test piece.
5) Longitudinal test piece, external diameter ˃ 508mm trans. test piece
6) Transverse test piece

Reference data on some physical properties

Density at 20°C kg/m3 7.9
Modulus of Elasticity kN/mm2 at 20°C 200
200°C 186
400°C 172
500°C 165
Thermal Conductivity W/m K at 20°C 15
Specific Thermal Capacity at 20°C J/kg K 500
Electrical Resistivity at 20°C Ω mm2 /m 0.73

Coefficient of linear thermal expansion 10-6 K-1 between 20°C and

100°C 16.0
200°C 16.5
300°C 17.0
400°C 17.5
500°C 18.0

Processing / Welding

Standard welding processes for this steel grade are:

  • TIG-Welding
  • MAG-Welding Solid Wire
  • Arc Welding (E)
  • Submerged Arc Welding (SAW)
  • Laser Beam Welding

When choosing the filler metal, the corrosion stress has to be regarded, as well. The use of a higher alloyed filler metal can be necessary due to the cast structure of the weld metal. A preheating is not necessary for this steel. A heat treatment after welding is normally not usual. Austenitic steels only have 30% of the thermal conductivity of non-alloyed steels. Their fusion point is lower than that of non-alloyed steel therefore austenitic steels have to be welded with lower heat input than non-alloyed steels. To avoid overheating or burn-through of thinner sheets, higher welding speed has to be applied. Copper back-up plates for faster heat rejection are functional, whereas to avoid cracks in the solder metal, it is not allowed to surface-fuse the copper back up plate. This steel has an extensively higher coefficient of thermal expansion as non-alloyed steel. In connection with a worse thermal conductivity, a greater distortion has to be expected.
When welding 1.4550 all procedures, which work against this distortion (e.g. back-step sequence welding, welding alternately on opposite sides with double-V butt weld, assignment of two welders when the components are accordingly large) have to be respected notably. For product thicknesses over 12mm the double-V butt weld has to be preferred instead of a single-V butt weld. The included angle should be 60° - 70°, when using MIG-welding about 50° are enough. An accumulation of weld seams should be avoided. Tack welds have to be affixed with relatively shorter distances from each other (significantly shorter than those of non-alloyed steels), in order to prevent strong deformation, shrinking or flaking tack welds. The tacks should be subsequently grinded or at least be free from crater cracks. 1.4550 in connection with austenitic weld metal and too high heat input the addiction to form heat cracks exists. The addiction to heat cracks can be confined, if the weld metal features a lower content of ferrite (delta ferrite). Contents of ferrite have to be welded (stringer bead technique) because a higher cooling speed decreases the addiction to hot cracks. A preferably fast cooling has to be aspired while welding as well, to avoid the vulnerability to intergranular corrosion and embrittlement. 1.4550 is very suitable for laser beam welding (weldability A in accordance with DVS bulletin 3203, part 3). With a welding groove width smaller than 0.3mm respectively, 0.1mm product thickness the use of filler metals is not necessary. With larger welding grooves a similar metal can be used. With avoiding oxidation within the seam surface during laser beam welding by applicable backhand welding, e.g. Helium as inert gas, the welding seam is as corrosion resistant as the base metal. A hot crack hazard for the welding seam does not exist, when choosing an applicable process. 1.4550 is also suitable for laser beam fusion cutting with nitrogen or flame cutting with oxygen. The cut edges only have small heat affected zones and are generally free of micro cracks and thus are well formable. While choosing an applicable process the fusion cut edges ca be converted directly. Especially, they can be welded without any further preparation. While processing only stainless tools like steel brushes, pneumatic picks and so on are allowed, in order to not endanger the passivation. It should be neglected to mark within the welding seam zone with oleigerous bolts or temperature indicating crayons. The high corrosion resistance of this stainless steel is based on the formation of a homogeneous, compact passive layer on the surface. Annealing colours, scales, slag residues, tramp iron, spatters and such like have to be removed, in order to not destroy the passive layer. For cleaning the surface the processes brushing, grinding, pickling or blasting (iron-free silica sand or glass spheres) can be applied. For brushing only stainless steel brushes can be used. Pickling of the previously brushed seam area is carried out by dipping and spraying, however, often pickling pastes or solutions are used. After pickling a careful flushing with water has to be done.

Remark

In quenched condition the material can be slightly magnetizable. With increasing cold forming the magnetizability increases.

Editor

thyssenkrupp Materials (UK) Ltd
Cox’s Lane
Cradley Heath
West Midlands
B64 5QU

Important Note

Information given in this data sheet about the condition or usability of materials respectively products are no warranty for their properties, but act as a description. The information, we give on for advice, comply to the experiences of the manufacturer as well as our own. We cannot give warranty for the results of processing and application of the products.

up to top