I have an 5.5mm of WireRod which is annealed&pickled. I am trying to draw that wires to 1 mm but something is going wrong. After first die, the tensile strength is getting increase 2 times of begining. What should be the process, anyone knows?
All plastic deformation have huge impact on hardening because of dislocation movement/production. When You changing the shape of metal You produce new dislocations, changing the grains shape and boundaries. If dislocation cant move they accumulate on the defect structure and block each other, what of course influence on properties. The impact depends on atomic structure: higher for dense packaging planes metals (such as copper alloys). If You want to make it back to 'normal' properties You have to heat the steel between next extrusion. If You will not - there is the huge risk of cracking the mold cavity.
Hi
Janus's explanations are entirely accurate and correct; So, you need to perform annealing to soften your material
While wire drawing of stainless steel (SS), the tensile strength can increase substantially (say as high as 3700 MPa) and lubrication is important. Please see whether these references are useful to you:- (i) Chapter 19 on 'Drawing of wire, rod and tube' in Book "Handbook of Workability and Process Design" edited by George E. Dieter, Howard A. Kuhn, S. Lee Semiatin, 2003, ASM International. (ii) paper by T.-S. Cao ET AL., Journal of Materials Processing Technology 217 (2015) 30–47. (iii) "Some problems of multi-stage fine wire drawing of high-alloy steels and special alloys", A. Skolyszewski, J. Luksza, M. Packo, Journal of Materials Processing Teleology 60 (1996) 155-160 and (iv) the paper in RG site:-https://www.researchgate.net/publication/229382510_Deformation_analysis_of_surface_flaws_in_stainless_steel_wire_drawing
Article Deformation analysis of surface flaws in stainless steel wire drawing
Due to the low stacking fault energy in stainless steels and high strain hardening rate as well as creating more strain on the surface than the depth of the wire in the wire drawing process, as much as possible, select maximum elongation in wire drawing and select suitable lubricant.
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