Q345(A, B,C, D, E) Steel Plate

 

 

Here is the analysis of production advantages and defects of Q345 (A, B, C, D, E) Steel Plate:

I. Production Advantages

Q345 is a widely used low-alloy high-strength structural steel in China (equivalent to international standard S355), divided into quality grades A, B, C, D, and E (with progressively higher impact toughness and lower impurity content). Its mature production process offers significant advantages:

1. Excellent Comprehensive Mechanical Properties

High Strength: Yield strength ≥345 MPa, higher than ordinary carbon steel (e.g., Q235), suitable for load-bearing structures (bridges, factories, pressure vessels), reducing material usage and achieving lightweight design.

Balanced Toughness and Ductility: Through alloy design (e.g., Mn/Si solid solution strengthening, Nb/V/Ti microalloying) and rolling processes (e.g., controlled rolling and cooling), the steel combines good impact resistance and plastic deformation capacity.Impact Toughness Grades:

Grade	Impact Test Temperature (℃)	Minimum Impact Absorption Energy (KV2, J)
A	Not required	-
B	+20	27
C	0	27
D	-20	27
E	-40	27

2. Superior Processability

Good Weldability: Low carbon content (≤0.2%) and low carbon equivalent (CEV) reduce cracking risk during welding, suitable for on-site fabrication of large steel structures.

Excellent Hot/Cold Working Performance: Can be formed via hot-rolling, cold-rolling, bending, and stamping to meet complex component requirements.

 

 

 

 

 

II. Production Defects and Shortcomings

Despite its advantages, Q345 production may encounter defects requiring process optimization or quality control:

1. Chemical Composition Segregation

Manifestation: Uneven distribution of alloy elements (Mn, C) or impurities (S, P) in continuous casting billets, leading to local strength/toughness variations.

Causes:

Rapid casting speed or uneven cooling causing dendritic segregation.

Insufficient secondary refining time leading to incomplete alloy homogenization.

Impact: Segregation may form banded structures after rolling, reducing transverse properties (e.g., impact toughness).

2. Surface Defects

Common Types:

Scale Press-In: Unremoved oxide scale during hot-rolling embeds into the surface, forming pits or pockmarks.

Cracks: Unrepaired billet surface cracks expand into plate cracks (edge cracks, transverse cracks) during rolling.

Scabs: Slag entrainment during smelting forms surface scabs after rolling.

Causes:

Poor continuous casting protection (e.g., mold level fluctuations, slag entrainment).

Inadequate descaling parameters (e.g., low high-pressure water pressure).

 

 

 

 

 

 

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 Q345(A, B,C, D, E) Steel Plate, and develop new technical specifications and processes.
Our customers trust us to deliver high-quality Cold-rolled Steel products on time and on budget.
We strictly implement the warm and thoughtful after-sales service, adhere to the development of good professional ethics.
We offer a wide range of Cold-rolled Steel products to meet diverse customer needs.
We adhere to the customer-centric and brand-oriented business philosophy, and continue to provide customers with reliable and excellent products and services.
Our factory is committed to upholding the highest standards of safety and quality.
All staff of our company and all departments work together to combine business management, professional technology, quantitative statistical methods and ideological education.
Our Cold-rolled Steel products are known for their durability and reliability.
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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