Effect of Laser Surface Melting on Structure and Properties of a High Speed Tool Steel

Abstract

The purpose of this research paper is focused on the high speed steel surface layers improvement properties using HPDL laser. The paper present laser surface technologies, investigation of structure and properties of the high speed steel alloying with carbides using high power diode laser HPDL. Investigation indicate the influence of the alloying carbides on the structure and properties of the surface layer of investigated steel depending on the kind of alloying carbides and power implemented laser (HPDL). In the effect of laser alloying with powder of carbides occurs size reduction of microstructure as well as dispersion hardening through fused in but partially dissolved carbides and consolidation through enrichment of surface layer in alloying additions coming from dissolving carbides. Introduced particles of carbides and in part remain undissolved, creating conglomerates being a result of fusion of undissolved powder grains into molten metal base. The structural mechanism was determined of surface layers development, effect was studied of alloying parameters, gas protection method, and thickness of paste layer applied onto the steel surface on structure refinement and influence of these factors on the mechanical properties of surface layer, and especially on its hardness, abrasive wear resistance, and roughness. It has the important cognitive significance and gives grounds to the practical employment of these technologies for forming the surfaces of new tools and regeneration of the used ones.

Characterization and Performance of Laser Alloyed Commercial Tool Steels

“…The non-uniform material heating resulting from the laser beam impact causes development of a big surface tension gradient on the surface of the liquid. The force is directed outside from the beam centre where is the highest temperature value to its edge and causes movement of the molten material [4]. Density of power delivered to the surface layer of the processed materials is lower for the more and more often used HPDL type lasers compared to its single mode distribution characteristic for other laser types; however, the energy is distributed more uniformly across the rectangular area of the laser beam focus.…”

Formation of Hard Composite Layer on Tool Steel by Laser Alloying

“…Mostly used laser technologies include alloying, fusion penetration, and remelting, which provide the highest quality surface coatings with thickness of 0.1÷1.5 mm and very high quality adhesion with the substrate which can be used for the significant part of metal elements made with tolerance below 0.1÷0.5 mm, when the progressive flank wear tool life criterion does not exceed 0.1÷0.5 mm. Layers made with the laser technique, apart from the very good metallurgical joint with the substrate, provide high corrosion resistance, abrasive wear resistance, high heat resistance and hardness, as well as ductility, plasticity and fatigue resistance, which are difficult or even impossible to obtain with other technologies [6][7], [15][16][17][18].…”

“…Mechanical and tribological properties of alloys obtained in this way are hard to acquire in the conventional technological processes [4,5]. High cooling rates are obtained in this process and its end result is the fine-grained material with the super-cooled phases [6][7][8]. Material transport in the remelting place is under the responsibility of surface tension forces and decide of the emerging morphology of the alloyed surface layer [9][10][11][12][13][14].…”

“…The force is directed outside from the beam centre where is the highest temperature value to its edge and causes movement of the molten material [4,[6][7][8]. Thanks to the very precise energy delivery laser radiation makes it possible to carry out the technological operations better or faster within the framework of the technologies known to date.…”

Characterization of Nanometric-Sized Carbides Formed During Tempering of Carbide-Steel Cermets

“…So far examination of carbide-steel cermet produced by powder injection moulding was carried out mainly in the scanning electron microscope. The purpose of this article is to examine the precipitated carbides using techniques available in transmission electron microscopy [1][2][3][4][5][6].…”