Behaviour of 32 CrMoV12-10 Steel Towards Boronizing Variables

During the shooting in gun barrels; there are many forces that affect each other such as external swelling caused by the explosion, excessive wear caused by the bullet core rubbing inside the barrel, high temperature caused by friction and gunpowder temperature, thermal expansion caused by temperature, chemical corrosion caused by gunpowder gases. It is expected that the barrel steel will show optimum resistance against all these effects. The most harmful of these is the wear force. The barrel, whose inner diameter expands due to wear, becomes unusable after a certain number of shots. In order to increase the effective number of shots, different hardening applications are made to the inner surfaces of the barrels of very different steel qualities. One of the commonly used barrel steels is 32CrMoV12-10 steel and hard chrome plating of the inner surface of the barrel. In this study, the boronizing behavior of 32CrMoV12-10 steel was investigated as an alternative coating technique. The changes in the type, layer thickness and hardness values ​​of boron compounds formed on the surface as a function of temperature and time were investigated. Boriding processes were carried out with a holding time of 2, 4 and 6 hours by setting the boriding temperature to 900oC. Typical columnar structures were observed at depths of 73, 100 and 133 μm in SEM microscope images. XRD (X-Ray Diffraction) analysis revealed that these were FeB, Fe2B, MnB and CrB compounds and that boride depth and hardness increased as the holding time increased. In microhardness tests conducted in this area, hardness values ​​up to 2500 HV were obtained.