No. 55 steel performance characteristics and heat treatment analysis

1. No. 55 steel is a carbon structural steel plate. The executive standard is GB/T 711, which is a steel grade named after carbon content.

2. We often see the corresponding grade of No. 55 steel as: S55C, which is a grade of carbon structural steel plate under the Japanese standard.

3. No. 55 steel plate heat treatment method: heat treatment can be done or not. The corresponding heat treatment is determined according to the design requirements. Common heat treatments are: annealing, normalizing or high temperature tempering, etc.

4. Chemical composition of No. 55 steel: C: 0.52-0.60; Si: 0.17-0.37; Mn: 0.50-0.80; S ≤0.035; P ≤0.035; Cr ≤0.25; Ni ≤0.30; Cu ≤0.25.

5. Mechanical properties of No. 55 steel:
Tensile strength σb/Mpa: ≥645(66); Yield strength ≥380(39); Elongation ≥13; Reduction of area ≥35; Hardness: unheated, ≤255HB; Annealed steel≤217HB.

6. Heat treatment temperature requirements for No. 55 steel: normalizing, 820℃; quenching, 820℃; tempering, 600℃.

7. The performance characteristics of No. 55 steel: after heat treatment, it has higher strength and surface hardness, but the corresponding plasticity and toughness are relatively poor. The cutting performance is medium, the welding performance and hardenability are poor, and sometimes there are signs of crack formation for the water quenching.