Investigation of the effects of hardening parameters applied to SAE/AISI 4130 steel used in the production of drilling drills on mechanical properties

Nowadays, drilling operations are used for many different processes. Drilling is essential in any operation conducting under ground. The most common drilling methods are: ground survey, water exploration, mineral exploration, geothermal and oil and natural gas deep well drilling. Drilling rods are used in mineral ore exploration. After the drilling process has started, progress on the ground is made with new rods added. In the studies it is carried out that the drilling rods used in core drillings are produced using the ERW method. Starting off with the raw material selection, the production of drill rods made of SAE/AISI 4130 steel in the steel mill, the coiling of the produced slabs in the rolling mill, the slitting of these coils in the pipe factory at the appropriate width, the pipe production method and the selected quality to work properly and safely in the field were studied. It is aimed to improve the mechanical properties of drilling rods made of SAE/AISI 4130 (25CrMo4) steel by applying heat treatments. For this purpose, the drilling rods were heated in the furnace. 10 drill rod samples with a diameter of 88,9 mm, a wall thickness of 5,55 mm and a length of 300 mm were heated in the furnace. The samples, which were kept in the oven for 30 minutes at 3 different predetermined temperatures (950 °C, 1000 °C and 1050 °C), were placed in the cooling mechanism of our own design. The cooling system has a 3 kW motor, a radial fan with an air flow capability of 2650 m3/h and steel materials of certain dimensions. The samples cooled with 3 different parameters (20 m/s, 40 m/s and 60 m/s) are then subjected to laboratory tests to determine their mechanical values. In the comparative experimental group formed with 9 samples; while working with 3 different heating temperatures and 3 different cooling parameters, 1 sample was heated in the oven at 1000 °C and then cooled at room temperature. The samples were subjected to tensile, microhardness, metallographic examination, notch impact and abrasion tests in the laboratory. As a result of the experimental studies; it has been observed that the samples heated at 1050 °C and cooled at 60 m/s have higher tensile strength and hardness values than the samples heated at lower temperatures and cooled at lower speeds. As the hardness increases the absorbing ability of the material, known as toughness, decreases. As a result, the notch impact values of the samples heated at higher temperatures and then cooled faster were measured to be lower.