1. Different types
42CrMo steel belongs to plastic mold steel in terms of material classification, and 45 steel is a high-quality carbon structural steel.
2. The chemical composition ratio is different
The chemical composition ratio of 42CrMo steel: C: 0.38～0.45%, Si: 0.17～0.37%, Mn: 0.50～0.80%, S: allowable residual content ≤0.035%, P: allowable residual content ≤0.035%, Cr: 0.90～1.20 %, Ni: allowable residual content≤0.30%, Cu: allowable residual content≤0.30%, Mo: 0.15～0.25%.
45 steel chemical composition element ratio (%): C: 0.42～0.50; Cr: ≤0.25; Mn: 0.50～0.80; Ni: ≤0.25; P: ≤0.035; S: ≤0.035; Si: 0.17～0.37.
3. Different hardness
42crmo steel hardness: annealing, 255～207HB, 45 steel hardness\HB:≤197.
