Refining
Goal:
The purpose of this thermal treatment is to achieve a granular structure, while increasing offset yield strength and toughness and a slight change in its hardness.
Applications:
High-tension components are made with the least possible dimensions of alloyed and non-alloyed steels. For example, in the Jig and Fixture building, the receiver levers are made of refining steels.
Methods:
refining is carried out according to the following steps.
Warming up to hardening temperature and quench (the hardening principles as already said is true here too) and
Return at high temperature
.Selection of refining steel:
The choice of refining steel depends on the cross-sectional area and the offset yield strength or optimum toughness.
Non-alloy refining steels in large sections are not refined deeply and comprehensively because the critical cooling velocity inside the work piece is not achievable. For this reason, alloyed refining steels are used in large sections and high loading.
Table 1: Heat treatment of refining steel
| Return temperature C | Hardening temperature C | Normal annealing temperature C | Soft annealing hardness HB 30 | Soft annealing temperature C | Short characteristic according to DIN 17006 | Material number |
|---|---|---|---|---|---|---|
| 660...550 | 890...860 | 910...880 | 156 | 700...650 | C 22 | 1.0402 |
| 660...550 | 850...820 | 870...840 | 207 | 700...650 | Ck 45 | 1.1191 |
| 680...540 | 860...830 | 880...850 | 248 | 700...650 | 30 CrNiMo 8 | 1.6580 |
| 680...540 | 850...820 | 880...840 | 217 | 720...680 | 42 CrMo 4 | 1.7225 |
Table 2: Relationship between tensile strength and elongation of relative length with cross-section
| Extension of relative length to% in thickness | Tensile strength to N / mm2 in thickness | Short characteristic according to DIN 17006 | Material number |
||||||
|---|---|---|---|---|---|---|---|---|---|
| 180...100 mm | 100...41 mm | 40...17 mm | 16 mm | 180...100 mm | 100...41 mm | 40...17 mm | 16 mm | DIN 17006 | |
| - | - | 22 | 20 | - | - | 640...490 | 690...540 | C 22 | 1.0402 |
| - | 17 | 16 | 14 | - | 760...620 | 800...660 | 840...700 | Ck 45 | 1.1191 |
| 11 | 10 | 9 | 9 | 1180...980 | 1270...1180 | 1180...1230 | 1420...1230 | 30 CrNiMo 8 | 1.6580 |
| 13 | 12 | 11 | 10 | 930...780 | 1180...980 | 1270...1080 | 1270...1080 | 42 CrMo 4 | 1.7225 |
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