what grade is 4140 steel

what grade is 4140 steel?4140 alloy steel material is a high quality Quenched and Tempered Alloy Structural steel,

what grade is 4140 steel?It belong to the high quality medium carbon alloy steel, Oil Quenched & Tempered Hardenss is 28-34 HRC.

what grade is 4140 steel,4140 Annealing delivery hardenss less than 250HB.

what grade is 4140 steel