Hardfaced

Other uses of oxyacetylene flames in mill operations are in building up or hardfacing metal, lancing (piercing a hole in a metal mass), and a variety of metal cleaning procedures. A minor but interesting fuel use of acetylene is in flame spectrophotometry where oxygen and nitrous oxide are used as oxidants in procedures for a wide variety of the elements. 

Both macrocrystalline WC and the fused WC—W2C eutectic (Fig. 1) are important in the manufacture of diamond drill bits used in the mining, oil and gas, and constmction industries, and in hardfacing rods and electrodes. The properties of WC are Hsted in Table 1. 

Chromium carbide is important in powder preparations designed for thermal spray apphcations of corrosion and wear-resistant coatings on tool and machine parts. Lower carbon carbides of chromium are important in hardfacing tods and electrodes for weld-apphed ovedays on machine wear surfaces. However, these carbides are usually formed in situ from Cr and C in the rod and not added as preformed carbides. The properties of Ci2C2 are hsted in Table 2. 

High-chromium cast irons and hardfacing alloys... 

Select a bit with tungsten carbide inserts on gage if sand streaks are expected in the formation. Do not depend on gage hardfacing alone to hold the hole to gauge. 

Solid-Type Stabilizers. (See Figure 4-180.) These stabilizers have no moving or replaceable parts, and consist of mandrel and blades that can be one piece alloy steel (integral blade stabilizer) or blades welded on the mandrel (weld-on blade stabilizer). The blades can be straight, or spiral, and their working surface is either hardfaced with tungsten carbide inserts or diamonds [57,58]. 

Stabilizer. Hardfacing Stabilizer. Alloy steel with tungsten carbide hardfacing. (Servco) compacts. (Servco)... 

Hardfacing Type 3 tungsten carbide, etc. overlay-weld deposit of 0,8 mm (0,030 in) minimum finished thickness, or, if available, a solid cast part of equal material may be substituted. 

Non-metallic wear part materials, which are proven to be compatible with the specified process fluid, may be proposed within the above limits. See 5.7.4.C. Such materials may be selected as wear components to be mated against a suitably selected metallic component such as hardened 12 % Cr steel or hardfaced austenitic stainless steel. Materials may be used beyond these limits if proven application experience can be provided, and if approved by the purchaser. ... 

Menstruum WC is used in hardfacing as well as in high-impact nonmachining applications. 

Cobalt alloys are used for hardfacing to improve the resistance to abrasion, galling, and/or impact Stellite 6 (60Co-29Cr-5W) (UNS R30006) is an example. Most alloys are in closure... 

Chromium is a refractory metal having a melting point of 3375°F (1857°C). Neither chromium metal nor chromium-based alloys are widely in the hydrocarbon or chemical industries. Chromium plating is useful for aesthetic purposes, and hard chromium plating finds some use in hardface applications. It is extensively used as an alloy addition to low-alloy steels (usually for the purpose of stabilizing carbides) and in cast irons (to produce wear-resistant products) and nickel alloys (for increased corrosion resistance). Chromium is the main alloying addition in the 400-series stainless steels and is used extensively in the 200- and 300-series stainless steels. 

In Sour Crude Service it has been suggested that the hardness of the plug should be specified lower than the standard 40-45 Rockwell C to 35-40 Rockwell C. The lowering of plug hardness prevents hydrogen sulfide corrosion. It is also recommended that a hardfaced seat be used to prevent hydrogen embrittlement. The standard carbon-steel seat is reported to have failed because of hydrogen embrittlement in crude service. 

The reader need not look for the exotic kind of hardfacings that either can only be applied in ultra-thin layers or are constantly being referred to in the literature as promising meaning that they are still at the development stage. 

A special hardened steel auger with new installed steel front auger (both hardfaced with Stellite 6) was used for the determination of basic abra-... 

Hardfacing, on the other hand, is a thick layer process. By means of varions welding techniques, wear-resistant alloys in rod, wire, or powder form build strong metallurgical bonds in the fused state with the surface, which is also fused. Mixing should be kept as low as possible. There is an exceptionally large variety of additives available therefore, the requirement for mechanical workability... 

INDIRA, R., Choice of Hardfacing Materials for LMFBR Components, Proc. National Symposium on Radiation Physics (NSRP-13), Mangalore, 1999, Indian Society for Radiation Physics, Mangalore University, Mangalore, India (1999) p. 459. 

Pol, 1994Pol] determined the compositions of phases presented in C-Fe-V alloys in order to assess which phases are best suited for the C-Fe-V hardfacing materials. In accordance with these results, for the compositions presented in Table 1, VC0.76 stoichiometry was in the best agreement between experimental results and calculations. [2001Wan] estimated the influence of V on the C solubility in the C-Fe melt using thermodynamic calculations. 

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