Tungsten-molybdenum High-speed Steels Research Articles

Effect of heat treatment on microstructure and impact toughness of a Tungsten-Molybdenum powder metallurgical high-speed steel

Effect of quenching, tempering and deep cryogenic treatment (DCT) on microstructure and impact toughness of a new tungsten-molybdenum high-speed steel produced by powder metallurgy was investigated. The obtained results infer that the microstructure is mainly composed of martensite, M 6 C and VC. The impact toughness decreases with the increasing of austenitizing temperature, but when the austenitizing temperature increases to 1180 °C, the impact toughness changes little. DCT after quenching improves impact toughness slightly, but DCT followed tempering has little effect on impact toughness. The fracture micromechanism can be identified as that crack initiates at the interface between M 6 C and martensite caused by the inconsistency deformation, M 6 C carbides exhibit broken or cleavage fracture and VC carbides decohere at the interface. In addition, the variation of impact toughness value has been explained by the characteristics of martensite, the fracture ductility, compressive strain of martensite lattice and grain refinement are beneficial to impact toughness. • The type of carbides and interface relationship was obtained. • Evolution of microstructure during heat treatment was studied. • The role of carbides in impact toughness was investigated. • The variation of impact toughness value has been explained by the characteristics of martensite.

BÖHLER S700

Abstract Böhler (or Boehler) S700 tungsten-molybdenum high-speed tool steel has good wear resistance and red hardness. This datasheet provides information on composition and physical properties. It also includes information on forming, heat treating, and machining. Filing Code: TS-778. Producer or source: Voestalpine BÖHLER Edelstahl GmbH & Co KG.

BÖHLER S705

Abstract Böhler (or Boehler) S705 is a cobalt alloyed, tungsten-molybdenum high-speed steel. Applications include turning and planing tools of all types, milling cutters,taps, twist drills, woodworking tools, and cold work tools. See also Alloy Digest TS-761, April 2019. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on heat treating and machining. Filing Code: TS-776. Producer or source: Voestalpine BÖHLER Edelstahl GmbH & Co KG.

BÖHLER S705

Abstract Böhler (or Boehler) S705 is cobalt alloyed, tungsten-molybdenum high-speed steel possessing high hardness, excellent cutting properties, high red hardness, and good toughness. See also Alloy Digest TS-776, September 2019. This datasheet provides information on composition, physical properties, and elasticity. It also includes information on forming and heat treating. Filing Code: TS-761. Producer or source: Voestalpine High Performance Metals Corporation.

Structural and phase changes in carbides of the high-speed steel upon heat treatment

The effect of austenitizing temperature on structural and phase changes in carbides of the tungsten–molybdenum high-speed steel has been studied. The results of metallographic analysis and energy dispersive microanalysis have been discussed. It has been shown that an increase in austenitizing temperature from 1180 to 1260°C causes structural transformations in carbide particles of eutectic origin crushed upon hot plastic deformation, which are related to their dissolution and coalescence, and changes in the phase composition of the carbides themselves.

Effect of modifying tungsten additions on formation of primary structure of R6M5-type high-speed steel

The effect of modifying additions of powder and compact (in the form of chips) tungsten on the formation of the primary structure of the R6M5-type tungsten-molybdenum high-speed steel has been investigated. The results of metallographic and electron microprobe analyses of base and modified steels have been discussed. It has been shown that the modification of the R6M5 steel with tungsten brings about considerable qualitative and quantitative changes in the microstructure of the matrix and carbide component of eutectic origin.

Structural transformations during heat treatment of W-Mo cast high-speed steel modified using titanium diboride

The effect of the austenitizing temperature on the transformation of the primary structure of a tungsten-molybdenum high-speed steel of the R6M5 type modified by an addition of a titanium boride powder has been studied. The results of metallographic, X-ray diffraction, and electron-microprobe analysis of the steel have been discussed. It is shown that an increase in the austenitizing temperature from 1180 to 1260°C causes significant structural transformations both in the carbide constituent and in the steel matrix.

Special features of microstructure of W– Mo high-speed steel modified with titanium diboride

The effect of a modifying additive of titanium diboride on formation of primary structure in tungsten-molybdenum high-speed steel of type R6M5 is investigated. Results of metallographic, x-ray diffraction, and microscopic x-ray spectrum analyses of the base and modified steels are discussed. It is shown that modifying of steel R6M5 with titanium diboride causes qualitative and quantitative changes in the microstructure of the matrix and of the carbide component.

Special features of transformations, structure and properties of molybdenum high-speed steels

The advantages of molybdenum high-speed steels over tungsten and tungsten-molybdenum high-speed steels due to the special features of their transformations and structures are shown.

Effect of silicon and germanium on the structure and properties of cast high-speed steel

The effect of silicon and germanium additives on the structure and properties of cast cobalt tungsten-molybdenum high-speed steel of type R6M5K5 is studied. Results of metallographic and x-ray diffraction analyses of experimental steels after casting, annealing, quenching, and tempering are discussed. The interrelation of the structural parameters, the degree of contamination of the metal with nonmetallic inclusions, and mechanical parameters is determined with respect to the amount of additives of both elements.

On the wear resistance of high-speed steels

The wear resistance of cast and strained high-speed steels are evaluated and compared, and the regularities of variations in their structure and properties depending on the austenitizing temperature are described. The impact of modification on the wear resistance of tungsten-molybdenum high-speed steels has been studied. Data on the steels with improved wear resistance are reported

Modifying Cast Tungsten-Molybdenum High-Speed Steels with Niobium, Zirconium, and Titanium

The influence of modifying additives of niobium, zirconium, and titanium on the structure and properties of cast tungsten-molybdenum high-speed steels R6M5 and R6M5K5 is studied. Results of metallographic and x-ray diffraction analyses and of studies of fracture surfaces of the steels after casting, annealing, hardening, and tempering are discussed. The relationship between structural parameters, the degree of contamination of the metal by nonmetallic inclusions, and mechanical properties is established. It is shown that modifying with the mentioned elements in optimum amounts primarily promotes an increase in the impact toughness and wear resistance of the metal.

Application of Bismuth for Solidification Structure Refinement and Properties Enhancement in As-cast High-speed Steels

In order to exhibit good all-round performance the impact toughness enhancement of as-cast high-speed steels is obligatorily needed. In general, different methods are used commercially to achieve cast structure refinement and, as a consequence, their properties are improved. Introduction into the melt of inoculant particles or surface-active additions is among most beneficial. However, the effect of modifying additions in as-cast high-speed steels has been studied insufficiently. In fact, a restricted number of modifiers is used for structure and properties improvement in the as-cast high-speed steels compared to the common cast alloys. In the present work several kinds of alloys including tungsten-molybdenum high-speed steels of M2 and T30 types and low-alloy tungsten-free 1.1C-5Mo-1.7V high-speed steel were melted to investigate the effect of bismuth on their structures and properties.It has been found that additions of bismuth produce a very fine cast structure and affect the shape of the matrix grains and the morphology of the eutectic carbides as well as the redistribution of the main alloying elements of high-speed steels between solid solution and eutectic carbides. The microstructural changes, induced by bismuth during solidification, are explained by the surface activity of bismuth, which segregates to liquid/solid interface, significantly blocking dendrite growth in the direction along certain crystallographic planes. It has been shown that during eutectic solidification, carbides are also exposed to the barrier effect of bismuth being surrounded in the melt by this element. The main metallographic features of the modified cast structure alongside with the purifying effect produced by bismuth are retained after full heat treatment affecting the final mechanical properties of as-cast high-speed steels. As a result, bismuth significantly increases impact toughness and wear resistance of as-cast high-speed steels but decreases their red hardness.

Use of REM-Based Modifying Agents for Improving the Structure and Properties of Cast Tungsten-Molybdenum High-Speed Steels

Special features of the structure and properties of cast high-speed steels R6M5K5 and R6M5 modified by REM-based additives, i.e., ferrocerium in a design amount of 0.1, 0.3, 0.6, and 1.2% and silicomishmetal and alumoyttrium in a design amount of 0.1, 0.3, and 0.6% are studied. Results of metallographic, x-ray diffraction, fracture surface, and microscopic x-ray spectral analyses of the steels after casting, annealing, hardening, and tempering are discussed. It is shown that the modifying changes the chemical composition, morphology, and distribution of the carbide component in the steels. Relation between the structural parameters and the characteristics of mechanical properties is determined.

Effect of modification on the structure and properties of cast tungsten-molybdenum high-speed steels

Effect of modification on the structure and properties of cast tungsten-molybdenum high-speed steels

DOUBLE SIX M-2

Abstract DOUBLE SIX M-2 is a tungsten-molybdenum high-speed steel with a well-balanced composition suitable for a wide variety of applications. It has replaced 18-4-1 type in many applications because of its superior properties and relative economy. This datasheet provides information on composition, physical properties, and hardness as well as fracture toughness. It also includes information on low and high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: TS-459. Producer or source: Latrobe Steel Company.

Effect of nitrogen on the stabilization of austenite in a tungsten-molybdenum high-speed steel

A study was made of the tendency of steels R6M5 and R6Am5 to austenite stabilization after subzero treatment and high-temperature tempering in hot-rolled bars. Data indicate that in steel R6AM5 during quenching there is almost instantaneous austenite stabilization. The data was derived from a study of phase composition (exposure from a microsection in DRON-2.0 equipment in iron K /SUB alpha/ radiation), microstructure, and hardness. The authors conclude that in view of serious difficulties in metallurgical and tool production, steel R6AM5 should be supplied only at the request of the customer.

MOLITE 4

Abstract MOLITE 4 is a high-carbon, high-vanadium, tungsten-molybdenum high-speed steel that approaches the ultimate in wear resistance for high-speed steels in this group. The advantages in using this steel comprise (1) Very high wear resistance, (2) High red hardness, (3) Good toughnes and (4) Moderate grindability. Among its many uses are punches and dies for blanking and forming thin sheet, milling cutters, twist drills, reamers, forming rolls, cold-extrusion punches and draw dies. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on forming, heat treating, and machining. Filing Code: TS-447. Producer or source: Columbia Tool Steel Company.

JESSOP MUSTANG

Abstract JESSOP MUSTANG is a tungsten-molybdenum high-speed steel that contains vanadium. It offers excellent cutting ability and, for most applications, its performance excels the tungsten-base (18 tungsten-4 chromium-1 vanadium) high-speed grades. It is often used as a general-purpose high-speed steel. Among its many applications are boring tools, broaches, cutters, drills, end mills, gear cutters, lathe tools, taps, punches and wood-working knives. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on forming, heat treating, and machining. Filing Code: TS-430. Producer or source: Jessop Steel Company.

Thermal stabilization and destabilization of austenite in tungsten-molybdenum high-speed steels

1. Processes that take place in the martensite exert a major influence on stress relaxation in the austenite of steels R6M5 and R6M5K5 and its stabilization: Preliminary tempering at 300–400°C almost completely stabilizes the austenite of the hardened steel owing to vigorous carbon impoverishment of the martensite and its compression, and subsequent heating and high tempering lead to destabilization of the austenite; Holding of the hardened steel at 20°C for two months stabilizes the austenite virtually completely; Holding at 20°C also stabilizes the austenite, lowering the tendency to secondary martensitic transformation after high tempering; the most vigorous stabilization is observed after holding for 1–5 days; the stabilization effect is reduced for extended holding times (to 30 days); and, Segregation of carbon (carbides) from the martensite during isothermal holding in the 20–400°C interval, or at temperatures of the secondary transformation result in stabilization of the austenite; segregation of cementite-type carbides from the martensite during cooling after high tempering in the 420–380°C interval activates a secondary transformation of the austenite.