Partial annealing method for large forged steel backup rolls
A technology of partial annealing and backup rolls, applied in the field of roll heat treatment, can solve the problems of reducing the hardness of the roll neck, reducing the surface hardness of the roll body, and increasing the machining cost, so as to reduce heat loss, reduce hardness and reduce cost consumption. Effect
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Embodiment 1）
[0018] In this embodiment, a large forged steel backup roll made of 5% Cr is taken as an example, and the technical requirement for the hardness of the large forged steel backup roll made of 5% Cr is 62-71 HSD.
[0019] figure 2 is the hardness value of the roll body and roll neck of the large forged steel back-up roll after primary surface quenching, given by figure 2 It can be seen from the figure that the hardness of the large forged steel back-up roll body is lower than the technical requirements, and secondary surface quenching is required.
[0020] Before secondary surface quenching, high temperature annealing treatment is required, the specific method is as follows:
[0021] ①Put the above-mentioned large forged steel support roll in an oven, firstly raise the temperature to 300°C for 3 hours, keep it warm for 14 hours, then raise the temperature to 600°C at 50°C / h, and keep it warm for 40 hours.
[0022] ②Preheat the differential temperature heat treatment furnace ...
Embodiment 2）
[0027] This embodiment is basically the same as Embodiment 1, except that: in step ①, before placing the large forged steel backup roll in the oven, paste refractory cotton.
[0028] This can further ensure that the hardness of the joints of the roll body and roll neck will not be reduced. In addition, the refractory cotton also increases the tightness with the water jacket, reducing heat loss.
[0029] After the local annealing method of this embodiment, the hardness values of the large forged steel back-up roll body and roll neck are shown in Figure 4 .
[0030] Depend on Figure 4 It can be seen that the hardness of the roll body of the large forged steel backup roll is reduced, and the hardness of the roll neck is the same as that of the roll neck. figure 1 Compared with no change, while the roll neck joint ( Figure 4 The hardness at R in ) is much higher than the hardness of the end surface of the roll body after annealing, and is similar to the hardness of the r...
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