Stress Relief and Spheroidising Annealing
In Norm Cıvata, the raw materials are subjected to stress relieving or spheroidising annealing in a coil shape (prior to cold forming). Not all raw materials are annealed and the type of annealing to be applied is determined according to the degree of cold forming difficulty of the final product.
While the stress relieving annealing is 15ton/charge capacity, the normalization annealing can increase up to 40ton/charge. Annealings are fully automatic and programs can be selected according to the raw material group. Stress relief can be done up to 700 oC and in spheroidising annealing, temperature can be increased to 900 oC when necessary.
Stabilization (Quenching + Tempering)
We use our heat treatment furnaces operating 24/7 continuously in order to bring the semi-finished products for which cold forming has been completed into their final mechanical properties. All products reach quality 8.8, 10.9 or 12.9 in this process by exposing the steel to austenite phase by heating in a controlled atmosphere and suddenly cooling in oil.
All parameters are automatically controlled and stored in our furnaces which have an average capacity of 1,200 kg/hour. With lot traceability, it is possible to go in the detail of raw material.
Unlike the mechanical properties specified in ISO 898-1 and 2, it is applied to remove internal stresses that come from cold forming in some products such as rivet nuts, bushings and rivets and that cause locally different hardness in the products and it can be increased up to a capacity of 250 kg/h. Also, since annealing is performed in a controlled atmosphere, no high temperature scaling occurs and the final surface quality is at a level that can be used without additional protection.
In all our heat treatment processes, we apply CQI-9, which is one of the automotive requirements and we share with the key industry and their tier-1 suppliers annually.