GR 70 is a grade of steel that is commonly used in structural applications, particularly in the construction industry. Here are some key properties and characteristics of GR 70 steel: - GR 70 is a high-strength, low-alloy (HSLA) steel - It has a minimum yield strength of 70 ksi (485 MPa) - It has a tensile strength of 80-100 ksi (550-690 MPa) - It has good weldability and is suitable for welding with common welding processes - It has good toughness and resistance to brittle fracture - It is often used in applications such as: - Building structures (beams, columns, etc.) - Bridges - High-rise buildings - Industrial equipment - Storage tanks GR 70 steel is known for its excellent strength-to-weight ratio, making it a popular choice for applications where high strength and low weight are critical. It is also known for its good corrosion resistance and ability to withstand harsh environments. Note: The "GR" in GR 70 stands for "Grade", and the number "70" indicates the grade level. The exact composition and properties of GR 70 steel may vary depending on the specific standard or specification (e.g. ASTM, ASME, etc.) being followed.