1. The grade of materials: 45, 20Cr, 40Cr , 35Cr Mo , 42Cr Mo, 20CrMnMo, 20CrMnTi, 17CrNiMo6, 20CrNi2Mo

2. Hardness: 56-60 HRC is the hardest; 40-55 HRC is the average hardness; below 28 HRC is the soft

3.Detection methods ultrasonic flaw detection,Manetic particle testing

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