Prakt. Met. Sonderband 30 (1999) 569
Pi
po TiN and Ti(C.N) coatings on high-speed steels with Ti addition: their structure and properties
ms L.A. Dobrzafiski, M. Adamiak
Ra Division of Material Processing Technology ‚and Computer Techniques in Materials Science,
hu Institute of Engineering Materials and Biomaterials, Silesian Technical University, Gliwice, Poland
ferürücke-
pores 1. Introduction
ig A significant share of tool costs in the total machinery and equipment manufacturing costs
Tr stimulates the continuing search for the new tool materials with even greater hardness and wear
or gy + resistance, and betterment of technologies improving the tools’ working parameters. Conventionally
manufactured high-speed steels are still important, in spite of the intensive development of modern tool
materials and spreading of ceramic and cermets materials, sintered carbides coated with multiple layers
with hard coatings, and also sintered high-speed steels, observed in last decades. Modem sintered tool
materials do not feature competition for high-speed steels due to their low ductility, and both these
material groups are mutually complementary. In all cases, where high ductility and good machinability
in the soft annealed state are the most desirable properties, high-speed steels are the dominating
materials employed for tools. Multipoint tools, tools for cold working and sometimes for hot working,
are made from these steels [1, 2]. Several development trends of high-speed steels’ and tools made
from them are noticeable. In general, one may discern among them technology changes, mainly
i powder metallurgy employed for their manufacturing. Improvement of the high-speed steels’ chemical
Di composition may be recognised as one of the most important factor of the ongoing increase of the
1-13 Set working properties of these materials [3, 4]. The optimised chemical composition attained in this way
may be found out, taking into account working properties of the tools, mostly their high cutting
properties and their lowest possible manufacturing costs.
i Applying thin, hard ceramic coatings made from the wear resistant materials in the PVD processes,
433 turned out to be the technology that attracted attention of tool manufacturers to high-speed steels again
[5]. PVD techniques make it possible to obtain an evident improvement of working properties of tools
made from the high-speed steels, whose technology is mastered to perfection. In contrary to the CVD
387-390 processes employed much earlier for coating sintered carbides, due to the relatively low temperature of
the PVD process, there is no risk of losing the properties obtained during heat treatment of tools made
162.169 from high-speed steels. For all the observed interest of numerous industrial centres and scientific
laboratories, many aspects of coatings’ generation and of the influence of the process conditions on
their properties still remain unexplained. Moreover, every combination of substrate material - coating
type - method of applying, calls for finding out the properties of the coated material and, basing on this
knowledge, determining the area of possible applications.
The aim of this work is investigation of the possibility of employment of the W-Mo-V+Si high-
speed steels with addition of Ti with the economically selected chemical composition as the substrate
material, and investigation of the structure and properties of the wear resistant coatings from the
titanium nitride TiN and titanium carbonitride Ti(C,N), deposited onto this substrate in the PVD
process.
2. Material for experiments
The investigations were carried out using the laboratory heats of the newly developed W-Mo-V
high-speed steels with the concentration of Si increased to about 0.7% and addition of Ti of 0.3%, of
the 9-2-2 and 11-2-2 types. These steels were melted in the VSG 50 Balzers vacuum furnace. Ingots of
the steels were subjected to spheroidising annealing, and later, after cutting off their lower portions and
top risers. were forged into square bars with 12 mm side size. Forged bars were subjected to
