Final answer:
The '70' in E7018-1H4R signifies the electrode's tensile strength of 70,000 psi, informing welders of the strength of the weld it produces.
Step-by-step explanation:
The number 70 in the code E7018-1H4R refers to the tensile strength of the welding electrode. The electrode can withstand 70,000 pounds per square inch (psi) of tensile stress. This is a standard designation used in welding to help professionals choose the correct electrode for their specific welding needs. Electrode classification codes like E7018-1H4R contain a wealth of information about the electrode type, tensile strength, welding positions, coating type, and any special properties or use cases.