SPCC was originally a Japanese standard (JIS) "general cold-rolled carbon steel sheet and strip" steel name.
Its chemical composition and mechanical properties are equivalent to Chinese brands Q195 and Q215A. The third letter C is the abbreviation of Cold. When you need to ensure the tensile test, add T to the end of the grade as SPCCT.
C ≤0.15 Mn ≤0.60 P≤0.100 S ≤0.025
45# is a grade of steel which is a high-quality carbon structural steel, corresponding to Japanese standard S45C, American standard: 1045, and German standard C45. Its characteristic is that it has higher strength and resistance to deformation than ordinary A3 steel.
Carbon C: 0.42～0.50; Chromium Cr: ≤0.25; Manganese Mn: 0.50～0.80; Nickel Ni: ≤0.25; Phosphorus P: ≤0.035; Sulfur S: ≤0.035; Silicon Si: 0.17～0.37
σb\Mpa:≥600 σs\Mpa:≥355 δ5\%:≥16 ψ\%:≥40 Hardness\HB:≤197
45# steel is a medium-carbon structural steel with good cold and hot workability, good mechanical properties, low price and wide sources, so it is widely used. Its biggest weakness is its low hardenability, large cross-sectional dimensions and high-demand workpieces.