GB/T 33968-2017 in English
SUPERSEDEDHot rolled steel sections with improved weldability
- Issued on:2017-07-12
- Implemented on:2018-04-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$136.00
| Standard No: | GB/T 33968-2017 |
| Document status: | SUPERSEDED |
| Superseded by: |
GB/T 33968-2025 Hot rolled steel sections with improved weldability
|
| Superseded on: | 2026-03-01 |
| Title in English: | Hot rolled steel sections with improved weldability |
| Title in Chinese: | 改善焊接性能热轧型钢 |
| Language: | English |
| File Format: | Electronic (PDF) |
| Delivery: | Via email within 1~3 business days |
| Issued on: | 2017-07-12 |
| Implemented on: | 2018-04-01 |
| ICS Classification: | 77.140.60-Steel bars and rods |
| Chinese Classification: | H44-Profile steel and deformed steel |
| Professional Classification: | GB-National Standard |
| Related Keywords: | steel sections
improved welding performance hot-rolled steel traditional hot-rolled steel bridge steel structure |
| Related Topics: | improve you
improve Flow Cytometry Improves Peak Shape steel Improve peak shape Improve verification improve experience Improving corrosion resistance of hot-rolled section steel improve t Welding performance hot rolled steel GBT33968 GB/T 33968-2017 |
《GB/T 33968-2017改善焊接性能热轧型钢》由TC183（全国钢标准化技术委员会）归口，TC183SC8（全国钢标准化技术委员会型钢分会）执行，主管部门为中国钢铁工业协会。
Introduction
GB/T 33968—2017 Interpretation of the Standard for Hot-rolled Steel with Improved Welding Performance
1. Background of Standard Formulation and Analysis of Technical Evolution
GB/T 33968—2017 Hot-rolled Steel with Improved Welding Performance is one of the important standards in China for improving the performance of special steels. This standard is based on the quenching and self-tempering process (QST) and aims to improve the welding performance and mechanical properties of hot-rolled H-shaped steel to meet the needs of modern buildings, bridges and other fields for high strength and high durability.
With the increasing demand for steel structures in construction projects, welding quality has become a key factor affecting structural safety. Traditional hot-rolled steel is prone to crack sensitivity during welding, so it is imperative to improve welding performance by optimizing chemical composition and production process. The introduction of the QST process is the core innovation of this standard.
2. Comparison of standard framework and technical requirements
| Standard dimension | GB/T 33968—2017 | Comparison standard | Difference analysis |
|---|---|---|---|
| Chemical composition control | Precisely limit the content of elements such as C, Mn, P, S, and optimize the ratio of alloy elements such as Cr, Mo, V | No mandatory requirements in conventional steel standards | Add Pcm index and CEV calculation formula to strengthen crack sensitivity assessment |
| Mechanical performance indicators | Specify key parameters such as upper yield strength and tensile strength, and require impact absorption energy ≥54J | Traditional standards only focus on basic mechanical properties | New low-temperature impact test and specimen size adaptability clauses |
| Production process requirements | QST process must be adopted, and the self-tempering temperature must be strictly controlled to be ≥600℃ | Specific production process is not specified | New ultrasonic non-destructive testing and surface quality inspection requirements |
3. Practical application case analysis
Case 1: Bridge steel structure welding
Q460QST steel is selected as the main beam material for a large cross-river bridge project. According to the standard requirements, the construction party needs to ensure:
- Hydrogen content of welding materials <10mL/100g
- Ambient temperature ≥ 0℃
- No complex rigid constraints on weldments
Case 2: Factory Truss Manufacturing
A steel structure factory uses Q355QST steel to make trusses. During the construction process, by strictly controlling the welding process parameters (such as interlayer temperature and cooling rate), the combination of high strength and high toughness was successfully achieved.
4. Implementation Suggestions
- Purchasing stage:Both the supply and demand parties should clarify the QST process requirements to ensure that the materials meet the requirements of GB/T11263.
- Production stage:Strictly control the chemical composition ratio according to the CEV calculation formula and Pcm index.
- Testing stage: Focus on impact test and ultrasonic nondestructive testing to ensure that the sample size meets the requirements of the specification.
- Construction stage: It is recommended to use automatic welding or semi-automatic welding equipment and optimize welding process parameters.
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