SAE4140 & SAE4142 are chromium, molybdenum, manganese containing low alloy steel. They have high fatigue strength, abrasion and impact resistance, toughness, and torsional strength.
JIS G4053 SCM435 steel is an alloy structural steel. It has high static strength, impact toughness and high fatigue limit and its hardenability is higher than 40Cr.