M-2A is a variant of modified M-2 especially suitable for tabs of thread tools.
Steel Properties : Comparing to M2, Grade TGM2A has low percentage of carbon, added Niobium. With low percentage of carbon to increase toughness, and Niobium added to fined crystal giants of steel to obtain high strength and toughness. This grade is specially suitable for tabs of thread tools.
Material : Forged / Hot Rolled round bars - Spherodized annealed - Grinding / turned / peeled.
Chemical Composition: (%)
Production Process :
| Under Annealed Condition : | Straightness : | Ovality : |
| Hardness: Max. 255HB | Max 2.0 mm/m | 1/2 *Tolerance |
Sizes of Round Bars :
| Cold Drawn/Ground Bar | Hot Rolled Annealed & Peeled Bar |
| Φ 2.0 - 14.4mm | Φ 14.5 - 80.0mm |
| Forged + Annealed + Turned Bar | Coil |
| Φ 81.0 - 255.0mm | Φ 2.0 - 13.5mm |
Non-Metalic Inclusions : Acc. to ASTM 45 method
A th. 1.0/heavy 0.5 - B th. 1.0/heavy 0.5 - C th. 1.0/heavy 0.5 - D th. 1.5 / heavy 0.5.
Microstructure : Acc. to SEP 1615
| ≤ 16mm | ≤ 16-25mm | ≤ 25-40m | |
| A | A | A | |
| B | B | B | |
| C | C | C | |
| TG Stage | 1B | 2B | 3B |
| ≤ 40-63mm | ≤ 63-100m | ≤ 100-160mm | ≤ 160-200m |
| A | A | A | A |
| B | B | B | B |
| C | C | C | C |
| 4B | 5B | 6A, 5B | 7A, 6B |
Grain Size : The grain size (ASTM) should be 10~11.5#
Ultrasonic Test : According to SEP 1921 class E/e/3, 100% scanning.
Heat Treatment :
| Soft Annealing | Cooling | Hardness |
| 780-860°C | 10-20°C/h furnace | Max. 280HB |
| Stress relief Annealing | Cooling |
| 600-650°C | furnace |
| 1st pre heating | 2nd & 3rd pre heating | |
| upto approx 450°C | a) 850°C | b) 850-1050°C |
| Hardening | Quenching |
| 1200-1220°C | Saltbath 550°C oil, air, vacuous |
Tempering :
Thrice 550-560°C Hardness after tempering 63-66HRC