The paper covers the research on the process of solutionizing of 7075 aluminum alloy in cold tools during the stamping of a high-strength structural element (B-pillar’s base). For technological reasons, in order to obtain high strength parameters of the 7075 alloy, it is necessary to carry out a solutionization process, which allows to obtain dispersion strengthening during ageing process. Properly performed heat treatment of the alloy increases the strength of the material to approx. 600 MPa. The combination of the process of solutionization with simultaneous shaping is aimed at improving and simplifying technological operations of aluminum alloy stamping, shortening the duration of the manufacturing process and reducing production costs. The manufactured lower part of the B-pillar will be used for the verification of the validity of the developed method. During the experiment, a series of stamping tests were carried out, in which the lubricants, pressure and position of the upper and lower blankholders were the variables. The obtained results allow to estimate the influence of the cooling conditions on the strength of the drawpieces obtained after the process of artificial ageing. In order to verify and analyse the results more quickly, a numerical simulation was carried out.
The study presents a durability analysis of dies used in the first operation of producing a valve-type forging from high nickel steel assigned to be applied in motor truck engines. The analyzed process of producing exhaust valves is realized in the forward extrusion technology and next through forging in closed dies. It is difficult to master, mainly due to the increased adhesion of the charge material (high nickel steel) to the tool’s substrate. The mean durability of tools made of tool steel W360, subjected to thermal treatment and nitriding, equals about 1000 forgings. In order to perform a thorough analysis, complex investigations were carried out, which included: a macroscopic analysis combined with laser scanning, numerical modelling by FEM, microstructural tests on a scanning electron microscopy and light microscopy (metallographic), as well as hardness tests. The preliminary results showed the presence of traces of abrasive wear, fatigue cracks as well as traces of adhesive wear and plastic deformation on the surface of the dies. Also, the effect of the forging material being stuck to the tool surface was observed, caused by the excessive friction in the forging’s contact with the tool and the presence of intermetallic phases in the nickel-chromium steel. The obtained results demonstrated numerous tool cracks, excessive friction, especially in the area of sectional reduction, as well as sticking of the forging material, which, with insufficient control of the tribological conditions, may be the cause of premature wear of the dies.