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