PSI - Issue 5

G. Lesiuk et al. / Procedia Structural Integrity 5 (2017) 912–919 Lesiuk et al./ Structural Integrity Procedia 00 (2017) 000 – 000

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Table 1. Chemical composition (in % by weight) of tested steel, puddle iron and old mild steel. Materials C Mn Si P S investigated steel 0.1 0.52 0.004 0.028 0.03 typical values for puddle iron <0.8 0.4 n/a <0.6 <0.04 typical values for old mild steel <0.15 0.2÷0.5 Variable <0.06 <0.15 Table 2. Monotonic quasi-static tension properties of the tested material, puddle iron, old mild steel. Materials  y/0.2 (MPa)  u (MPa) E (GPa) investigated steel 304 416 212 typical values for puddle iron 220÷280 330÷400 170÷200 typical values for old mild steel 250-300 340÷450 200÷220

The microstructure of investigated material is shown in Fig. 2.

Fig.2. The microstructure of investigated material: (a) structure of non-metallic inclusions, non-etched state, light microscopy; (b) ferrite grain structure in low magnification, etched 3%HNO 3 , light microscopy; (c) ferrite grain (A) structure with perlite areas (D), thick envelope of Fe3C III (C) on ferrite grain boundaries with typical degradation processes separations (B) inside ferrite grains; etched 3%HNO 3 , light microscopy; (d) enlarged ferrite grains (A) with degradation symptoms (B) manifested by the numerous of brittle separations, etched 3%HNO 3 , light microscopy. According to obtained results of material and mechanical investigations it should be state, that the investigated material is typical old mild steel commonly used at the beginning of the 20 th century in civil engineering. The microstructure, non-metallic inclusions distribution confirm this statement. In case of the puddle iron, the microstructure and mechanical properties slightly differs from obtained results – see the differences in papers of