After supplying the customer with SAE1018 material for many years, it became unavailable in 2021 as a result of the COVID-19 pandemic, resulting in a request for a material change / deviation to SAE1020. Our Sales Manager in Johannesburg arranged samples, only to find that they were cracking when bent into shape.

This was perplexing, as the only difference in the new material was a slight increase in the carbon content of 0.02%. This should have had no significant effect on the ductility / plastic deformation.

Our Sales Manager in Johannesburg then took the obvious measure of having the rods annealed, but this resulted in the rods becoming too soft and not retaining their shape under load.

Upon investigation, Andrew Johns and Jann Stovold found that the material shortage was resulting in a larger diameter of material being drawn down to the correct manufacturing size, which inherently work-hardened the material. As no other material of the correct ‘as rolled’ mill size could be found, further resulting in us facing a line stop, it was decided to send our stock to heat treatment for normalising.

Normalising worked; however, the heat treatment process caused the rods to discolour and rust quickly. So with the customer’s permission, a flash plating of 5 mic of zinc was applied.

We were then able to supply our customer with no line stop.