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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
Material number Short characteristic according to DIN 17006 Soft annealing hardness

HB 30

Soft annealing temperature

C

Normal annealing temperature

C

Hardening temperature

C

Return temperature

C

1.0402 C 22 156 650…700 880…910 860…890 550…660
1.1191 Ck 45 207 650…700 840…870 820…850 550…660
1.6580 30 CrNiMo 8 248 650…700 850…880 830…860 540…680
1.7225 42 CrMo 4 217 680…720 840…880 820…850 540…680

 

Table 2: Relationship between tensile strength and elongation of relative length with cross-section
 

Material number

Short characteristic according to DIN 17006 Tensile strength to N / mm2 in thickness Extension of relative length to% in thickness
…100

…180 mm

…41

…100 mm

…17

…40 mm

… 16 mm …100

…180 mm

…41

…100 mm

…17

…40 mm

…16mm
1.0402 C 22 490…640 540…690 22 20
1.1191 Ck 45 620…760 660…800 700…840 17 16 14
1.6580 30 CrNiMo 8 980…1180 1080…1270 1230…1180 1230…1420 11 10 9 9
1.7225 42 CrMo 4 780…930 880…1080 980…1180 1080…1270 13 12 11 10

 

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