Q420q alloy steel plate is a high-strength low-alloy (HSLA) steel specifically designed for bridge construction, adhering to the GB/T 714-2015 standard . It offers an optimal balance of strength, toughness, and weldability, making it a cornerstone material for modern bridge infrastructure. Below is a comprehensive analysis of its technical specifications, applications, and critical considerations for engineering projects:

1. Technical Specifications

Chemical Composition

Element	Content (%)	Role
Carbon (C)	≤0.11	Reduces weldability risks while maintaining strength.
Manganese (Mn)	1.0–1.7	Enhances hardenability and wear resistance.
Silicon (Si)	≤0.55	Improves oxidation resistance and structural stability.
Vanadium (V)	0.01–0.08	Refines grain structure for higher toughness.
Titanium (Ti)	0.006–0.03	Suppresses harmful carbide formation.
Niobium (Nb)	0.01–0.09	Enhances strength via precipitation hardening.
Phosphorus (P)/Sulfur (S)	≤0.030	严控杂质以确保 weldability and ductility .

Mechanical Properties

Yield Strength (σ₀.₂): ≥420 MPa (thickness ≤50 mm)
Provides stable load-bearing capacity for long-span bridges.

Tensile Strength (σ_b): 540–680 MPa
Resists dynamic traffic loads and fatigue cracking.

Elongation (A₅): ≥19%
Ensures ductility for complex fabrication processes.

Impact Energy (KV₂ at -40°C): ≥27 J (standard grade), ≥200 J (special marine grades)
Maintains toughness in extreme cold and corrosive environments .

Key Standards

GB/T 714-2015: Mandates chemical composition, mechanical properties, and ultrasonic testing.

AWS D1.5: Governs welding procedures for bridge fabrication.

GJB 1496B-2014: Optional for military-grade ballistic resistance in specialized applications.

 

 

 

 

 

 

 

2. Manufacturing Process

Production Steps

Melting:

Electric arc furnace (EAF) with ladle furnace (LF) refining to control impurities.

Vacuum degassing (VD) for high-purity grades (e.g., Q420qENH for marine use) .

Casting:

Continuous casting for thin sections (<100 mm) or ingot casting for thick plates (up to 150 mm).

Hot Rolling:

Thermo-mechanical controlled processing (TMCP) at 1,050–1,150°C to refine grain structure.

Heat Treatment:

Normalizing: 880–920°C for uniform mechanical properties.

Quenching & Tempering: Optional for higher strength-toughness balance in critical components.

Quality Control:

100% ultrasonic testing (UT) and magnetic particle inspection (MPI).

Ballistic certification via GJB 1496B-2014 for military applications .

Key Suppliers

China: Baowu Steel, Wuyang Steel (specialized in bridge steel), Xiangtan Iron & Steel (supplied Q420qD for the Macau Bridge) .

Certifications: ISO 9001 (quality), ISO 14001 (environmental), and GB/T 714 compliance.

 

 

 

 

 

 

 

 

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 Q420q Alloy 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.

Hot Tags: q420q alloy steel plate, China q420q alloy steel plate suppliers, factory, GH4180, HastelloyB-2, HastelloyC-4, N06455, N06600, NastelloyB