![]() Property class 50 represents the steel in the annealed condition. Indeed, class 70 and 80 properties are available above 39 mm but this must always be discussed with the supplier. This reflects the conservative nature of the previous 24 mm limit. The effect of these changes is to increase the maximum diameter on which the class 70 and 80 properties can be specified without discussion from 24 to 39 mm. Above that, the standard can still be used provided all parties agree that the properties can be achieved. However, there is a general clause which says that the standard is only applicable up to 39 mm diameter. This latest revision has removed the restrictions on the size of fastener (M24) for which the properties in table 2 can be guaranteed. To be determined on the actual screw length and not on a prepared test piece. ![]() The tensile stress is calculated on the stress area.Table 2 Mechanical properties for austenitic stainless steel bolts, screws and studs Table 2 shows the 0.2% proof stress, tensile strength and elongation values for each of these property classes. There are now four ‘property classes’ which are assigned selectively across the various austenitic stainless steel fastener grades now included in the standard. Mechanical properties for stainless steel fasteners This formula is used solely for the purpose of classifying duplex steels, it is not intended to be used as a selection criterion for corrosion resistance. May contain niobium, (columbium), and/or tantalum ≥ 10 × C up to 1 % maximum.May contain titanium ≥ 5 × C up to 0,8 % maximum.Molybdenum may be present at the discretion of the manufacturer.At the discretion of the manufacturer the carbon content may be higher, where required in order to obtain the specified mechanical properties at larger diameters, but shall not exceed 0,12 % for austenitic steels.Shall contain titanium ≥ 5 × C up to 0,8 % maximum for stabilisation and be marked appropriately in accordance with this table, or shall contain niobium, (columbium), and/or tantalum ≥ 10 × C up to 1,0 % maximum for stabilisation and be marked appropriately in accordance with this table.For austenitic stainless steels having a maximum carbon content of 0,03 %, nitrogen may be present to a maximum of 0,22 %.If the chromium content is below 17 %, the minimum nickel content should be 12 %.However, if for some applications limiting of the molybdenum content is essential, this shall be stated at the time of ordering by the purchaser. There is no minimum limit to the copper content provided that the nickel content is greater than 8 %.If the nickel content is below 8 %, the minimum manganese content shall be 5 %.Values are maximum unless otherwise indicated.Chemical Composition 1 (% maxima unless stated)
0 Comments
Leave a Reply. |