The Standard for Welding Electrodes and Rods for Low Alloy Steels
(GB/T 5118-1995)
1. Introduction
This standard applies to welding electrodes and rods that are made from low-alloy steels. It is also known as GB/T 5118-1995, which is established and issued by the General Administration of Quality Supervision, Inspection and Quarantine of the Peoples Republic of China on March 30, 1995. The purpose of the standard is to promote a consistent quality of low-alloy steel welding electrodes and rods.
The scope of this standard covers the properties, grades, size, selection, storage and collection of low-alloy steel welding electrodes and rods, to ensure the quality of welding. It also provides requirements for the chemical composition of electrodes, chemical composition of welds, impact toughness of welds, fatigue strength of welds, fusion porosity of welds, and slag firmness of welds, etc.
2. Terminologies
2.1 The definitions of the relevant terms in this standard include:
2.1.1 Welding electrode: A consumable electrode used in electric arc welding to fill the welding joint.
2.1.2 Welding rod: A consumable rod used in welding processes to form a weld.
2.1.3 Low alloy steel: Steel composed of mainly one-element alloy and other alloy elements lower than the amount defined in relevant national standards.
2.1.4 Specified deposit efficiency: The deposit efficiency required by the manufacturer specified in the steel structure standard and the welding process requirements.
2.1.5 Chemical composition: The chemical composition refers to the composition of the chemical elements that make up the welding electrode or welding rod.
2.1.6 Chemical composition of welds: The chemical composition of the weld metal.
2.1.7 Impact toughness of welds: The ability of welds to absorb energy during impact tests.
2.1.8 Fatigue strength of welds: The ability of welds to resist fatigue loading.
2.1.9 Fusion porosity of welds: The amount of voids in the welds.
2.1.10 Slag firmness of welds: The slag layer produced during welding, which affects the appearance of the welds.
3. Grades
The grades of low-alloy steel welding electrodes and rods shall be in the form of letters, numerals and symbols. The letters in the grade shall indicate the alloy element and its purity, the material composition of the weld metal, and its characteristics. The numerals shall indicate the tensile strength of the weld. The symbols shall indicate the characteristic properties of the welded joint.
4. Size
4.1 The size of the welding electrode and rod should meet the requirements of Table 1.
Table 1
Welding electrode and rod size
Length (mm) Diameter (mm) 150 ≥ 2.0 250 - 380 3.2 - 4.8 450 ≥ 5.0
4.2 The size of the welding electrodes and rods shall be determined by the manufacturer, taking into account the type of electrodes, customer requirements, the thickness of the weldmetal and the strength characteristics of the welded joint.
5. Selection
The selection of the welding electrodes and rods shall be based on the following factors:
5.1 The grade of steel that is being welded.
5.2 The thickness of the welded joint.
5.3 The required weld penetration.
5.4 The chemical composition and mechanical properties of the weld metal.
5.5 The required strength of the welded joint.
5.6 The customers requirements.
6. Storage and Collection
6.1 The welding electrodes and rods shall be stored in a dry, clean, and dust-free environment.
6.2 The welding electrodes and rods shall be collected in accordance with the designated segregation system.
7. Analysis and Tests
7.1 The chemical composition and mechanical properties of the welding electrode or rod shall be determined as per manufacturers requirements.
7.2 The impact toughness of the welds, fusion porosity of the welds, and slag firmness of the welds shall be determined as per the relevant national standards.
7.3 The welding electrode and rod shall be tested for fume emission, smoke emission and spatter emission.
8. Conclusion
This standard is established to ensure the quality of low-alloy steel welding electrodes and rods. It covers the properties, grade, size, selection, storage and collection of the electrodes and rods. It also provides requirements for the chemical composition, mechanical properties, impact toughness of welds, fusion porosity of welds, and slag firmness of welds. In addition, the welding electrodes and rods shall be tested for fume emission, smoke emission and spatter emission. This standard is issued and enforced by the General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China.
