标准AAR M-107/M-208
*If the manufacturer chooses to vary from the above limits for nickel, chromium, molybdenum,and vanadium, the following formula must be met:
930 – [570 × % carbon] – [80 × % manganese] – [20 × % silicon] – 50 × % chromium] – [30 × % nickel] – [20 × % molybdenum + % vanadium] > 390