How can you compare with metals' ductility and malleability? 5

[kokerkov]

Hi layman here,

Background:
We need some special cross section(semicircle) wire to produce cotter pins, and we found a workshop can do this using round wire. Surely by some kinds of pressing or rolling, I dont know exactly. And, we are providing raw materials(Inconel 625) to them.

Question：
However, they haven't dealt with such material before, they are not sure which round wire size to use. Since this material is rather expensive and has a MOQ, we dont want to risk losing money. They are familiar with stainless steel and carbon steel(for springs) wire though.

So which data should they looking at when comparing this Inconel 625 with materials they are familiar with? Elongation? Poisson's ratio? Or others?

 

[mfgenggear]

OP
Their tooling will wear out sooner,
For example shearing dies. Will require replacing or resharpening.

Inco 625 is more abrasive and tough.
Take the size diameter wire and
Due destructive test with charpy
Apply shear loads test and compare
With standard materials.
Special die material will be required.

 

[EdStainless]

The forces needed to form a metal are more closely related to the resulting mechanical strength than the starting properties.
Are they going to draw it or roll it to form the shape?
Rolling will involve a lot less wear and force.
You are going to want the cross section of the starting wire to be slightly larger than the finish cross section, but not too much.
When drawing tube, I can make area reductions of 40-45% in plain steels, 25-30% in austenitic stainless steel, and 20% in 625.
All of our tooling is carbide (WC) and lubricants are everything.

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P.E. Metallurgy, consulting work welcomed

 

[jessieleo99]

Here are some key points and some specific data you need to consider in relation to stainless and carbon steels with which you may be familiar:

Yield Strength: Inconel 625 is a material with a yield strength of around 414 MPa; that's about 215 MPa for common 304 stainless steel and carbon steel A36, it's about 250 MPa. This means you will need far more force to deform Inconel 625 compared to the other materials.

Work hardening rate: The work hardening rate for Inconel 625 comes in at about 0.25, while for 304 stainless steel it comes in at approximately 0.34. While the Inconel 625 has a slightly lower rate of hardening during deformation, it still undergoes hardening to a significant degree that would make the material progressively difficult to work with during pressing or rolling.

Ductility: Elongation at break in Inconel 625 is about 30-40%, while that for 304 stainless steel is around 40-50%, and carbon steel A36 has an elongation at break of about 20%. This means that Inconel 625 is still quite ductile, although slightly less than stainless steel but more than carbon steel.

Modulus of Elasticity (Young's Modulus): Inconel 625 has about a 205 GPa Young's modulus, while that of 304 stainless steel is about 193 GPa, and carbon steel A36 is approximately 200 GPa. All these values are for a much stiffer Inconel 625 as compared to the others; hence, it would slightly differ in elastic response during processing.

Thermal Properties: Inconel 625 has a coefficient of thermal expansion of 12.8 µm/m°C. For comparison, 304 stainless steel is 17.3 µm/m°C, and carbon steel A36 is 12.1 µm/m°C. That means Inconel 625 will grow less when heated and also shrink less when cooled—so you'll need to factor in these differences as you adjust your process temperatures and cool-down rates.

https://powder.samaterials.com/

 

[EdStainless]

The typical yield strength for 625 will be 500-600MPa, 414 is the minimum.
With 304L the minimum is 170MPa (205 for high C material) but typical is more like 225-325.
With a fairly light cold reduction the 304L will end up 700-800MPa, and the 625 will be more like 850-950MPa.
If you are drawing or rolling none of the other properties really matter.
Because of the strength and toughness of 625 it tends to be very abrasive on tooling.
The real issue is how hard do you want this material?
It will be very difficult to work with when you start getting to 1000MPa.

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P.E. Metallurgy, consulting work welcomed

 

[cnc king]

Maybe ,you should focus on several key properties:

1.Yield Strength: This is crucial to determine how much force the material can withstand before it begins to deform permanently. Inconel 625 typically has higher yield strength compared to stainless steel and carbon steel.

2.Work Hardening: Inconel 625 may behave differently under cold working (like pressing or rolling) compared to the materials they are familiar with. They should understand how much the material hardens when deformed.

3.Ductility (Elongation): This indicates how much the material can stretch before breaking, which is important when forming a specific shape, like a semicircular cross-section.

4.Poisson’s Ratio: This can help understand how the material’s cross-sectional area changes under tension or compression.

5.Modulus of Elasticity: This is important for understanding how stiff or flexible the material will be during the forming process.

These properties will help them make a more informed decision on the wire size and processing parameters.

 

[mfgenggear]

Cnc king very well explain.
In my industry, AL metals were formed in the annealed condition, as it is formed it work hardens then requires sub sequent annealing for more forming process. Once the shape is achieved it
Is final heat treated. And really depends on the fit, form and function.