YB13-1969 "Ordinary Low Alloy Structural Steel Grades and General Technical Conditions"

YB13-1969 "Ordinary Low Alloy Structural Steel Grades and General Technical Conditions"

At the same time as the revision of YB13-1963, there are 8 special standards for low alloy steel that are to be revised and formulated.

Under the specific historical conditions at that time, YB13-1969 had two major revisions. First, the name of the original standard "low-alloy structural steel" was changed to "ordinary low-alloy structural steel"; second, the so-called "Group II steel" and "left behind ingots" were added. These two revisions undoubtedly played an inestimable role in reducing the quality and standard level of low alloy steel, and had a great negative impact on the development of low alloy steel in my country.

The grade series of YB13-1969 has been greatly adjusted, and a total of 22 grades are included:

09MnV, 09MnNb, 09Mn2, 12Mn, 18Nbb, 08MnPRE, 09MnCuPTi, 09Mn2V, 09Mn2Si, 12MnV, 12MnPRE, 14MnNbb, 14MnNb, 16Mn, 16MnRE, 10MnPNbRE, 1jMnV, 1jN5nTi, 16MnV16MnMNb, 1.

Among them, only 3 grades of the original standard are retained, 09Mn2, 16Mn and 15MnTi. Part of the grades in the original standard were transferred to the special standard, and the other part of the grade was cancelled. These newly included grades clearly reflect the characteristics of my country's resources, with manganese, vanadium, niobium, titanium and rare earths as the main alloying elements. However, some immature and even inferior grades have also been included in the standard. In fact, there are not many grades that can be produced normally, and most of them are still 16Mn.

The strength level of the brand is reduced from 7 to 5 in the original standard, the strength is increased to 440MPa, and the strength difference is increased to 49MPa, which is more reasonable. However, the strength level of 16Mn, a typical low-alloy structural steel produced in large quantities, is significantly reduced.

GB/T 13—1969 General Low Alloy Structural Steel Grade and General Technical Conditions

With the rapid development of industrial technology, steel has become the most widely used engineering material, and its application has been extended to large-scale architectural structures, ships and bridges. In order to meet the needs of modern industrial production and engineering construction, General Low Alloy Structural Steel has been developed. This steel grade is characterized by excellent comprehensive performance, allowing high strength design, easy welding and uniformity. GB/T 13—1969 is a folder that contains the mandatory rules of General Low Alloy Structural Steel Grade and General Technical Conditions.

This norm is divided into 21 parts, covering the product classification, ordering information, product use and manufacturing process, inspection and acceptance rules, packaging, transportation and storage, marks, certification and other contents.

Product classification mainly includes low alloy structural steel, low alloy steel for hot-rolled/cold drawing, electroslag and submerged arc welding. The ordering information includes machining requirements and steel grade delivery conditions.

Product use and manufacturing process mainly regulate the allowed stress and deformation of the steel during processing, welding, heat treatment and other manufacturing processes, as well as the performance requirements of each technical indicator after processing.

Inspection and acceptance mainly include the general test method, mechanical property, chemical composition test method and the corresponding inspection and acceptance rules.

Packaging transportation and storage mainly regulate the requirements for packaging and transportation of steel products, such as the extent of harmful corrosion, the allowable amount of deflection and the degree of protection against moisture.

The standard also stipulates the requirements for steel marks and certificates, so as to guarantee the quality of the whole process of steel production, inspection and service life.

This standard applies to general low alloy structural steels with chemical components not higher than 2.25%. These steels are characterized by excellent comprehensive performance, high strength design, easy welding and uniformity. They have been widely used in bridges, ships and other engineering structures.