AISI 4130 steel is a medium carbon, low alloy steel in ASTM A29 standard. ASTM 4140 steel is also commonly referred to as a chromoly steel, or chrome moly steel.
AISI 4340 steel is a medium carbon, low alloy steel. There are some equivalents of 4340 steel, such as: 817M40/EN24 and 1.6511/36CrNiMo4 or Japan based SNCM439 steel.
EN 34CrNiMo6 Steel is an important alloy engineering steel grade as per BS EN 10083-3:2006. 34CrNim06 steel has high strength, high toughness and good hardenability.
BS EN 42CrMo4 Alloy Steel is a common chromium-molybdenum steel that usually used after quenched and tempered, with high intensity, high hardenability. 42CrMo4 Alloy Steel is widely used in engineering steel.
AISI 4140 steel is a chromium molybdenum alloy steel which is widely used as tool steel in industry. where greater toughness and wear resistance is needed over lower carbon grades.