Steel Plate S55C

1. Material Overview

S55C is a medium-carbon high-quality structural steel specified in the Japanese JIS standard (JIS G4051:2015). With a moderate carbon content (approximately 0.55%, ranging from 0.52% to 0.58%), it offers a balance of high strength and moderate toughness, making it suitable for mechanical parts requiring comprehensive mechanical properties. The designation means:

 

S: Steel

55: Average carbon content of ~0.55%

C: Carbon steel

2. Core Properties

1. Mechanical Properties (Typical Values, Subject to Standards)

Condition	Yield Strength (σ<sub>s</sub>, MPa) ≥	Tensile Strength (σ<sub>b</sub>, MPa) ≥	Elongation (δ<sub>5</sub>, %) ≥	Reduction of Area (ψ, %) ≥	Hardness (HBW)
Hot-rolled/Normalized	315	600	16	40	≤217
Quenched & Tempered	430	685	14	45	217–255

 

Note: Impact toughness depends on the heat treatment condition; medium-carbon steels generally have lower impact resistance than low-alloy steels.

2. Process Performance

Weldability:
High carbon content (CEV ≈ 0.55%) leads to poor weldability, with a tendency to form cold cracks. Preheating to 150–250°C is required before welding, and post-weld slow cooling or tempering is needed to relieve stress.

Workability:

Excellent machinability; suitable for turning, milling, etc. Use cutting fluid during machining.

Limited cold deformation capacity; hot forming (e.g., forging) requires heating to 850–950°C to avoid cracking.

Heat Treatment:

Quenching & Tempering: Significantly improves comprehensive mechanical properties (balance of strength and toughness).

Surface Hardening (e.g., induction heating): Increases surface hardness to ~50HRC, suitable for wear-resistant parts.

3. Chemical Composition (JIS G4051:2015, %)

Element	Content Range	Role Description
C	0.52–0.58	Primary strengthening element; increases strength and hardness but reduces plasticity and weldability.
Si	0.15–0.35	Deoxidizer; slightly improves strength but reduces toughness if excessive.
Mn	0.60–0.90	Refines grain size, improves hardenability and strength; combines with sulfur to reduce hot shortness.
P	≤0.030	Strictly controlled to minimize cold brittleness.
S	≤0.035	Strictly controlled to reduce hot brittleness; moderate sulfur improves machinability.

 

 

 

 

 

 

 

 

Why Choose Us?
We take pride in our ability to provide custom solutions for our customers' unique needs.
We analyze and compare the previous products and the current technical situation of our Steel Plate S55C, and develop new technical specifications and processes.
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Relying on the superior conditions and strong advantages of mass production, we are able to meet the different needs of our customers.

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