Grade 1.4305 is a free-machining stainless steel. In common with other austenitic grades like 1.4301 and 1.4307, it contains about 18% chromium and 9% nickel but the steel is also alloyed with sulphur for improved machinability. In general, stainless steels are regarded as more troublesome to machine than carbon steel but in 1.4305, the sulphur addition improves machinability to a degree that it is not so far removed from that for a free-machining carbon-manganese steel.
Ground round bars in 1.4305 are standardised in EN 10088-3. This standard covers cold-finished round bars with diameters up to 160 mm even though it is normally only smaller dimensions that are available in ground execution. Tibnor’s programme encompasses diameters up to and including 60 mm.
In comparison with 1.4301 and 1.4307, the sulphur addition to 1.4305 results in somewhat impaired corrosion resistance. However, the steel withstands atmospheric corrosion rather well at the same time as it is reasonably resistant to attack by rain water and less aggressive chemicals.
Ground bars of 1.4305 can be shaped by cold forming but it should be remembered that sulphur reduces ductility which means that cold formability is less good than for 1.4301 and 1.4307. The presence of sulphur also confers a risk for hot cracking in connection with welding which is not to be recommended for this grade.
The surface finish of ground 1.4305 as stocked is 2G as defined in EN 10088-3. Grinding is carried after hot-rolled bars have been annealed, pickled if necessary and the surface pre-processed through either cold drawing or peeling. Any remaining surface defects are eliminated. The diameter tolerance of ground bars is h8 or h9 as stipulated in ISO 286 - 2 which is a zero-minus tolerance. In other words, the actual diameter is marginally less than the nominal one. In addition, ground bars of stainless steel are very straight (height of arc less than 0.001 x length) with fine surface (Ra <1µm).