Final answer:
The 'HR' in E7018-1H4R stands for 'Hydrogen Resistant,' signifying that the welding electrode is designed to minimize hydrogen-induced cracking, particularly in high-strength steels.
Step-by-step explanation:
The notation E7018-1H4R refers to a type of welding electrode. The 'HR' in the notation stands for 'Hydrogen Resistant.' This indicates that the electrode is designed to produce welds that are resistant to hydrogen-induced cracking. This characteristic is particularly important in welding high-strength steels where the presence of hydrogen can lead to cracking in the weld metal or the heat-affected zone.
The prefix 'E' denotes an arc welding electrode, '70' indicates a minimum tensile strength of 70,000 psi, '1' refers to the electrode's suitable welding positions, '8' designates the coating and current type, and the suffix '-1H4' signifies the specific chemical composition catering to low hydrogen and other properties.
The "HR" in E7018-1H4R denotes specific characteristics of the welding electrode in accordance with American Welding Society (AWS) classification. In this context, "HR" stands for "High Resistance." E7018 is a type of low-hydrogen, iron powder, all-position electrode commonly used for welding carbon and low-alloy steels. The "1H4R" further specifies details such as welding positions and additional characteristics.
The "HR" aspect signifies the high resistance property, indicating that the electrode is designed to provide good resistance to cracking and deliver reliable welds, particularly in applications where hydrogen-induced cracking is a concern.