14/06/2022 – New drawing and quenching+tempering line in Ori Martin
Spring steels for cold forming
In 2020 Ori Martin installed a new Drawing and Quenching and Tempering line (IT Wire) to produce spring steels for cold forming, in particular 54SiCr6 – SAE 9254. The adjustment of some plant devices, such as annealing line and coiling line, combined with optimized operating practices enabled Ori Martin to have now a well distributed spectra of grades in this nitch catalogue, which is in continuous expansion.
The very promising results obtained in terms of microstructure, mechanical properties values and their homogeneity along the whole length of the wire, together with the high reliability of the process and of the results, brought Ori Martin to test the new line even on Cr/Mo and Boron steel grades
In 2020 Ori Martin Steel Works installed a new IT Wire Drawing and Quenching+Tempering line in Brescia’s plant, the final and more precious part of a fully integrated process form the billet continuous casting to the rolling of wire rod.
The main objective of the new plant was the production of spring steels for cold forming, with particular focus on 54SiCr6 – SAE 9254.
The new line is made of three principal blocks: the drawing line, the quenching and tempering line, the coiling line. The lay-out of the drawing line includes: a de-coiler, a pre-straightener, a shot blasting machine, a drawing (“cabestano” 1,200mm of diameter – 150kN) and two coilers. The line is also equipped with NDT controls:
– Foerster “Circograph RO20” and a Foerster “Defectomat” positioned between the shot blasting machine and the drawing;
– Laser dimensional control before coiling.
The lay-out of Quenching+Tempering line is made of: a pay-off+dancer, straighteners and a brushing and washing unit, the hardening zone (induction line + quenching nozzles), the tempering line (induction lines), CND controls as in the Drawing line, Chromatic marking (white color) of the surface defects of the roll with indication on the roll tag and on the production certificate of the number of defects detected, Oiler, shear.
The double coiler line at the end of quenching and tempering line consists of two coilers of 2,350mm diameter, used for spring steel 54SiCr6, and two coilers of 1,300mm of diameter used for Cr/Mo steels.
The line is able to produce a wire which is suitable for spring production, showing proper microstructure and mechanical properties, very homogeneous along the whole length of the wire with a very high reliability and reproducibility.
Actually the production is performed on three shifts, with a monthly productivity of about 750 tons, where almost the 70% is represented by 54SiCr6. The coil parameters for IT WIRE of 54SiCr6 are:
The extremely homogeneous mechanical properties and microstructure obtained along the new Drawing and Quench&Tempering line enable Ori Martin to increase the number of steel grades in portfolio with several Cr/Mo steels, used for different application such as drawing, cold forging, warm forging etc… avoiding the final heat treatment on the single pieces and with the guarantee of a safer component respect to micro alloyed steels.
As the end users of Cr/Mo steel grades need different coil dimensions compared respect to spring producers, different coilers have been installed to guarantee an external coil diameter of 1,300mm. The actual Ori Martin portfolio includes: 25CrMo4, 42CrMo4, 50CrMo4, 34NiCrMo6, 37Cr4, 41Cr4, 41CrS4. Many other steel grades are under evaluation, after some trials performed, such as C45, boron grades etc.
The authors are Marco Paura, Andrea Panizza, Simona Galassi, Francesco Busio
wire 2022, hall 12 booth B 16