Characterization of high phosphorous containing hot rolled weather resistant structural steels

Three steels (G22, G32 and SCOR) containing 0.15-0.19% phosphorous and different amounts of Cr, Cu and Ni were made in laboratory and characterized for evaluating mechanical and textural properties. The values of Charpy V notch impact (CVN) energy, YS, UTS and %EL of G22 and SCOR steels conformed to that of S235JR, S275JR and S335JR structural grades of EN10025-2:2004 specification. SCOR steel exhibited the highest CVN energy although it had the highest pearlite content (15.16%) and carbon equivalent (0.34). While CVN energy was suppressed significantly with increasing phosphorus concentration beyond 0.15%, it was also decreased on increasing Cr and decreasing Ni content as in the case of G32 steel. However, all specimens revealed dimpled fracture mode after tensile testing. In the case of G22 steel, Φ2 45° section of ODF obtained using EBSD revealed a weak but nearly uniform γ fiber texture ((<111>)||ND), an indicative of good forming quality of hot rolled structurals. Hot tensile and compression test was performed for evaluating casting and hot rolling problems. The reduction in area (RA) values obtained through hot tensile test in temperature range of 850-1100 °C were found to be greater than 60% for G22 steel. In contrary to this, susceptibility to hot cracking of G32 steel was attributed to its minimum RA value (37%) at 900 °C. The flow stress characteristics of G22 steel at different temperatures were comparable to that of other commercial grade structural steels.