Low Alloy Structural Steel Technical Conditions GB 1591-1979 Introduction The formulation and promulgation of GB 1591—1979 “Low Alloy Structural Steel Technical Conditions” is mainly to promote the development and use of steel structures with excellent performances in our country. GB 1591—1979 describes the requirements, various levels of quality and corresponding technical conditions, test methods, inspection rules, and packaging, marking and quality certification of steel products. An important breakthrough in this standard is that Q345 is newly issued. Contents Quality requirement; Technical requirements; Steel grade, chemical requirement and mechanical property; Test method; Inspection rule; Packaging, marking and quality certification. Quality Requirement
The GB 1591—1979 steel products should meet the requirements of both quality assurance and quality certified, and must meet the technical requirements of relevant steel grades in the standard or contracts. In mass production, the supplier should also meet the requirements of ISO quality management system and related product quality control. The supplier must have stable quality guarantee system and improve the competitiveness of the product in the market as much as possible. Technical Requirements Steel grade, chemical requirements and mechanical property should meet the requirements of this standard. These requirements include yield strength, tensile strength, elongation, impact energy and so on. The mechanical property and chemical composition of each steel grade should be struck out in the contract when purchasing. Otherwise, it should be based on the national standard mentioned before. Steel Grade, Chemical Requirement and Mechanical Property GB 1591—1979 provides the requirements of various steel grades. As an example, let’s take the Q235A steel grade as an example. The chemical requirement of this steel grade is as followings: C: 0.12-0.20, Mn: 0.30-0.67, Si: 0.30, S: 0.045, P: 0.045. The mechanical property of Q235A steel grade should meet the following requirements: tensile strength: 235-390MPa, Yield strength: 20-100MPa, elongation: 25-32%, impact energy: KV 20°C: 27J. Test Method GB 1591—1979 provides the commonly used test methods for low alloy structural steel. First of all, the tensile strength, yield strength and elongation should be evaluated by Tensile Test. Then, the correctness of the shape, size, surface and performance should be evaluated by Visual Inspection. The surface quality should be evaluated by Surface Detection. The impact energy should be evaluated by Impact Test. After the above tests are completed, the supplier should submit the test reports to the purchasing party to evaluate the quality of the products. Inspection Rule After the test results conform to the technical requirements specified in this standard or the contract, the supplier must submit the test report to the purchasing party for evaluation. After the purchasing party evaluates the test report and confirms that the quality conforms to the requirements, the supplier should make the shipment according to the contract requirements. Packaging, Marking and Quality Certification The supplier must specify the shelf life, packaging protection and marking of the steel products on the invoice or in the agreement. The packaging protection measures should be taken to ensure that the steel products are free from damage and deformation during transportation. The supplier must also attach the quality certification of the steel products in the agreement or invoice. Conclusion GB 1591—1979 “Low Alloy Structural Steel Technical Conditions” provides the requirements of various steel grades, chemical composition, mechanical property and test method. The supplier should meet the requirements of quality assurance and quality certified, so that the quality of steel products could be guaranteed.
