Cold working condition (H)


Copper and copper alloy cold processing is usually used cold-rolled and cold-drawn, individual cold forging and cold bending and other cold processing technology. After cold processing, some also need heat treatment.


1. Cold working state


The cold working state is divided into two types: the state level can be established based on the size reduction (cold deformation) and only the strength level can be established.


① With the size reduction (cold deformation) based on the establishment of cold processing status


For the rolling and drawing plate, belt, rod, wire, metal cold working deformation of the greater degree of its strength and hardness is also higher, copper and copper alloy cold rolling or cold drawing work hardening phenomenon to make each cold The product has a range of strength or hardness that can be applied to a variety of applications. The annealed metal is subjected to varying degrees of cold working deformation, and its strength is roughly proportional to the amount of cold deformation. The amount of deformation is represented by the number of Browne and Shape (B & S) scale numbers. In the B & S scale system, there is a fixed scale relationship between each scale and the other two scales. The scale number is reduced by about 10% for every additional grade and thickness (diameter) , The corresponding relationship in Table 2, H after the number and B & S scale number consistent.


Table 2 Cold working conditions based on the amount of cold shrinkage (cold deformation)


Level 3 Status Code Name B & S Scale Number Incremental Thickness or Diameter Reduction,%


H001 / 8 Hard -


H011 / 4 hard 110.9%


H021 / 2 Hard 220.7%


H033 / 4 Hard 329.4%


H04 Hard 437.1%


H06 special hard 650.1%


H08 Elasticity 860.5%


H10 high elasticity 1068.6%


H12 special flexibility 1275.1%


H13 higher elasticity -


H14 high elasticity 1480.3%


② to establish a cold working state based on the intensity level


Based on the cold shrinkage deformation grade level method can not be used for such as pipe, extrusion and casting these product types, and copper and copper alloy sometimes use some special cold processing, such as: cold forging, riveting, screw and bolt processing, U-tube cold Bending and fin-like pipe processing, these cold processing methods on the tensile strength and yield strength, have varying degrees of influence, but can not be used to reduce the amount of cold reduction corresponding to 1/8 hard, 1/4 hard or 1/2 hard To indicate its state, its state classification and manufacturing state M have a certain contact, Table 1 has been described in detail.


2. Cold processing after the heat treatment state


① Eliminate stress state HR


Copper and copper alloys below the recrystallization temperature are cold working to produce residual stresses that will result in stress corrosion and stress cracking (or "cracking") of certain copper alloys. Usually the method of eliminating stress is: mechanical elimination of stress (such as bending or straightening); heating to eliminate stress, that is, at a temperature below the recrystallization temperature of the temperature, commonly used in finished products. The status is shown in Table 3.


② orderly enhanced HT


(Such as C61500, C63800, C68000, C69000, etc.) when the alloying elements can dissolve into the phase and close to saturation, when subjected to large deformation cold processing and at a relatively low temperature (lower than the recrystallization temperature) heat treatment, by reducing The stress concentration in the dislocation gather point in the lattice is improved, the stress relaxation characteristic is improved and the yield strength is improved. Low temperature ordered strengthening can also be used to eliminate stress treatment.


③ tail annealing HE


After the pipe is hardened, it is necessary to anneal at the end of the pipe for flaring test.


The status is shown in Table 3.


Table 3 Heat treatment after cold working


Secondary state three state subdivision (code) status name


Cold work + elimination stress HRHR011 / 4 hard and stress relief


HR02 semi-hard and stress relief


HR04 hard and stress relief


HR08 elasticity and stress relief


HR10 high elasticity and stress relief


HR12 special elasticity and stress relief


HR20 finned stress relief


HR50 drawing and stress relief


Cold work + orderly enhancement HTHT04


HT08 hard + order intensive


Elastic state + orderly enhancement

Cold working + tail annealing HEHE80 hard drawing + tail annealing

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