Reduction of wear at hot forging dies by using coating systems containing boron

Abstract

The near surface area of forging dies is exposed to high mechanical loads. Additionally thermal and chemical stresses appear during the hot forging process. Depending on the number of forged parts, several kinds of stresses occur in the near surface area, which lead to the initial failures of forging dies. Wear is the main reason for production downtimes with a ratio of 70%. Furthermore, thermal and mechanical cracks are typical causes for failures causes as well as plastic deformation. In order to reduce wear, the abrasion resistance of the forging die surface has to be increased. Hence, different methods like plasma nitriding and optional additional thin hard coatings (TiN, TiCN, TiC, TiBN and TiB2) were successfully examined. Recently developed Ti-B-N coatings in specific multilayer designs are thermally stable, wear-resistant and anti-adhesive regarding the sticking of work piece material. This paper presents the wear reduction possibilities of boron-containing mult ilayer coating systems applied to forging dies by using the plasma enhanced chemical vapor deposition treatment. A basic mechanical and analytical characterization of different coating systems is realized in the first stage of the project. Best qualified multilayer coating variants were applied to forging dies for experimental investigations. As a result of the tests, wear can be reduced significantly by using thermally stable boron multilayer coatings. To receive realistic wear values under production conditions, an automated forging process was used for testing. After 3,000 forged parts, the coatings were examined by tactile measurement, SEM and EDX analyses to characterize the occurring wear

Deposition welding of hot forging dies using nanoparticle reinforced weld metal

“…For example nitriding and optional additional thin hard coatings [11] or deposition welding [12] are successful methods to reduce the wear in hot forging processes. Whereas nitriding and deposition welding are known as industrial standard, the application of thin hard coatings by chemical or physical vapor deposition is established only in few processes.…”

Directions of development and application of plasma nitriding in industry

“…Pored toga, oksidacijom površine radnog predmeta nastaju tvrde čestice poput kamenca koje uzrokuju veliko abrazivno habanje. Tokom proizvodnje, termičko opterećenje od obrade materijala biće praćeno ciklusima hlađenja što izaziva uslove termalnog šoka (slika 11b) [90].…”

“…Slika 11. Glavni mehanizmi habanja u ispitivanim alatima za kovanje u najviše opterećenim regionima [90] Figure 11. Main wear mechanisms in examined forging tools in the mainly loaded regions [90] Slika 12.…”

The Influence of the Third Element on Nano-Mechanical Properties of Iron Borides FeB and Fe2B Formed in Fe-B-X (X = C, Cr, Mn, V, W, Mn + V) Alloys

“…The surface modification of the materials is achieved by formation of a dual layer FeB + Fe 2 B or a monophase Fe 2 B layer by high-temperature diffusion of boron atoms (boronizing process) [ 3 ]. As such, these materials are utilized, for example, in the production of forging and stamping dies used in the manufacturing industry or valves, bearings and other production tubing system components used in the oil and gas industry [ 4 , 5 ]. Equally important is the application of boron for hardness enhancement through alloying, where the borides formed are utilized as hard reinforcing phases, e.g., boron alloyed tool steels [ 6 , 7 ], and high-boron white cast irons [ 8 , 9 , 10 , 11 , 12 ], etc.…”