The raw material for our wire (Fagersta Stainless AB) is wire rod exclusively from our own rod mill. The integrated production line Melting shop > rod mill > wire mill offers the opportunity to tailor compositional and product properties in accordance with specific customer requirements.
Our rod mill can produce wire rod in any of three product forms ( batch annealed, direct solution treated or D-cooled condition with grain sizes 3-6, 5-8 and 10 - 13 respectively ). This makes it possible to optimize properties like surface, grain size and mechanical properties.
Both the CWH-factor (cold work hardening factor) developed by Fagersta Stainless and the Md30 factor further developed by Nohara are used to control and optimization of the product properties for materials like T302, T304 and T305.
CWH, a value calculated from a data matrix of C, Cr and Ni contents, increases with increasing work-hardening rate in the steel. The factor can vary between 80 and, in extreme cases, 150 depending on the chemical composition of the steel grade.
Md30/Nohara indicates the temperature (°C) at which 0.3 true strain (approximately 25%) Area reduction leads to transformation of 50% of the austenite in the steel to deformation martensite. A higher value of the temperature indicates that the structure is more unstable (more prone to formation of martensite ) and leads to a higher work-hardening rate in the steel.
Md30/Nohara = 551 - 462 x ( C+N ) - 9,2 x Si -8,1 x Mn -13,7 x Cr - 20 x ( Ni + Cu ) - 18,5 x Mo - 68 x Nb - 1,42 x ( ASTM grain size - 8) |