Metallurgy
Ferrous Metallurgy
X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F
Ferrous metallurgy includes production of cast iron (blast-furnace process) and, using it as a base, production of plain, low- and high-allow steels and ferro-alloys. In blast-furnace process, the main materials to be analyzed are iron concentrate, coke, and fluxes (incoming inspection). Mg, Al, Si, Ca are to be detected both in concentrate and fluxes in addition to Fe.
The detrimental impurity – sulphur – is of primary importance in coke. As a rule, powdered samples are subject to analysis. At the blast-furnace process output, cast iron is subject to Mn, Cr, Ni, Ti, Si, S, P and carbon, which is detected through combustion. To control the process, slags are analyzed for Mg, Al, Si, Ca, Fe.
Manganese and chrome ores are processed to obtain ferro-alloys (ferromanganese and ferrochrome) used for alloying steels where the content of basic components and additives Si, Ti and S is controlled. Other chemical elements used for steels alloying are also used as corresponding ferro-alloys, which composition is strictly controlled to maintain the composition of the furnace charge of the steel grade being made.
Since certain elements are burnt and turn into slag when alloyed steels are made, the analysis of the melting progress is to be performed to bring the melt composition in compliance with that of the required grade. The only method ensuring the proper rapidity and accuracy of steels analysis in the course of melting is XSFA. Depending on the steel grade being made, alloying additives (which may include Ti, V, Cr, Mn, Co, Ni, Nb, Mo and W) usually introduced as ferro-alloys or secondary raw materials are determined. The content of these elements may vary from n×10-1 to 20 – 30%, depending on the steel grade. The melt sample is taken into a water-cooled copper mold. After the sample gets solid, it is cut, polished and sent to the laboratory via a pneumatic tube. The whole process, including the analysis, takes less than 10 minutes. If there are standard samples of all grades being made at the production facility, any method may be used for calculation of concentrations (if there are no proper standard samples, methods the theoretical correction or fundamental parameters may be used). After melting is completed, marking analysis is performed to check the quality of finished products, and results thereof along with the finished product are handed over to the consumer. Methods of steel XSFA are described in various regulatory documents. Some of them are given below:
1. GOST 28033-89. Steel. X-ray fluorescence analysis method.
2. ASTME1085-09. Standard method of low-alloy steel analysis by means of X-ray fluorescence spectroscopy.
3. ASTM E572. - 02a(2006)e2. Standard method of stainless and low-alloy steel analysis by means of X-ray fluorescence spectroscopy.
4. ISO 17054:2010. Routine method of high-alloy steel analysis by means of X-ray fluorescence spectroscopy and using the method of corrections.
General-Purpose X-ray diffractometers DRON-7(M) and DRON-8
X-ray diffractometers DRON-7 and DRON-8 are successfully used for qualitative and quantitative analysis of phase composition of ferrous and non-ferrous metals and alloys, as well as for detection of retained austenite in high-carbon steels; for control of metallurgical production waste (slags); for examination of grain patterns of rolled metal and for analysis of residual stress in steelworks.
Non-ferrous Metallurgy
X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F
As far as non-ferrous metallurgy is concerned, the metallurgical process may result in both pure metals and corresponding ferro-alloys or oxides and some metal compounds. As a rule, sulphide nonferrous metal ores (Co, Ni, Cu, Zn, Pb, Mo) are used most frequently, and for metal smelting sulphide concentrates previously separated by floatation are used. The first stage of sulphide concentrates processing is oxidizing flux roasting in reverberatory furnaces, with metal sulphides turning over into corresponding oxides. Roasting results are controlled by analysis. Further reducing roasting allows obtaining crude metals - Co, Ni, Cu, Zn, and Pb to be refined through electrolytic process. This method allows separating precious metals which are often present in detectable amounts in complex ores.
As far as metals used for steel alloying are concerned, reducing roasting with cast iron or iron concentrate and coke is used, which results in production of corresponding ferro-alloys (Ni, Mo, W). Rare metals Mo and W are processed to obtain oxides MoO3 and WO3, which are refined and used to obtain pure metals or their compounds.
Like during production of ferrous metals, fluxes and slags are analyzed during smelting of non-ferrous metals and detected for Mg, Al, Si and Ca in addition to smelted metals.
Complex processes of ferrous and non-ferrous metals production using concentrates of complex ores imply multiple analysis of early, intermediate and final products not only for base metals but also for numerous additives covering almost the whole Mendeleev's table, starting from Al, Si, S and P and ending with platinum-group metals, Au and Bi.
Use of BRA-135 is also possible and appropriate at separate stages of production of light metals (Mg, Al, Ti), for example, for control of the content of basic components and additives in ores and concentrates of these metals.
Among non-ferrous alloys, alloys based on copper (brass and bronze) and aluminum alloys are used most frequently. In addition to copper, copper-based alloys may include Zn, Ni, Fe, Mn, Sn, Pb, Bi, Si, P, Sb, Al, Be. Among all these metals only Be in beryllium bronzes cannot be detected by the XSFA method.
XSFA methods of alloys based on copper (bronzes and brasses) are described in various regulatory documents. Some of them are given below:
1. GOST 30609-98 Cast brasses. X-ray fluorescence analysis method.
2. GOST 20068.4-88. Tinless bronzes. Method of X-ray spectrum detection of aluminium.
3. GOST 30608-98. Tin bronzes. X-ray fluorescence analysis method.
Aluminium alloys may include Mg, Ti, Cr, Mn, Fe, Cu, Zn, Zr, Sn, Pb.
However one should emphasize that the method of fundamental parameters may have significant errors when applied to non-ferrous alloys often containing lead, due to micro-absorption discontinuity (lead is poorly soluble in copper and aluminium, thus producing individual inclusions). Because soft lead is spread over the surface during preparation of non-ferrous alloy samples, lathe machining rather than grinding is used.
XSFA is one of the main analysis methods for rare metal alloys that may include Al, Ti, V, Co, Ni, Zr, Nb, Mo, Nb W, Re and some additives. XSFA methods for rare metal alloys are described in regulatory documents:
1. GOST 28817-90. Hard sintered alloys. X-ray fluorescence method of metals detection.
2. GOST 25278.15-87. Alloys and addition alloys of rare metals. X-ray fluorescence method of detection of zirconium, molybdenum, tungsten and tantalum in niobium-based alloys.
3. ASTM B890 - 07(2012). Standard Test Method for Determination of Metallic Constituents of Tungsten Alloys and Tungsten Hardmetals by X-Ray Fluorescence Spectrometry.
4. ASTME539-07. Test Method for X-Ray Emission Spectrometric Analysis of 6Al-4V Titanium Alloy.
5. ASTM E2465-06. Standard Test Method for Analysis of Ni-Base Alloys by X-ray Fluorescence Spectrometry.
As with steels, XSFA is performed in the course of smelting, marking analysis of the finished product and incoming inspection using various analytical methods are performed.
General-Purpose X-ray diffractometers DRON-7(M) and DRON-8
X-ray diffractometers DRON-7 and DRON-8 are successfully used for qualitative and quantitative analysis of phase composition of ferrous and non-ferrous metals and alloys, as well as for detection of retained austenite in high-carbon steels; for control of metallurgical production waste (slags); for examination of grain patterns of rolled metal and for analysis of residual stress in steelworks.
Jewellery Alloys
X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F
Use of XSFA for analysis of jewellery alloys and items made thereof by means of the energy dispersion X-ray spectrometer Shimadzu, which is similar to BRA-135, is described in Application Note at the company’s site. Co, Ru, Rh, Pd, Ag, Pt, Au were detected. The content of precious metals in analyzed items equalled to 7 to 85%. A zirconium filter was used for measurements, with the 1 mm original radiation collimation. The analysis error equalled to 0.7 to 0.25%. The work by А. V. Fesenko and Н. Г. Milozorov [RUSSIAN JOURNAL OF GENERAL CHEMISTRY, 2002, vol. XLVI, №4, p.81-87.] has compared possibilities of existing analysis methods for gold alloys, including XSFA. General requirements to analysis of precious metals and their allows are described in the standard [GOST R 52599-2006. Precious metals and their alloys. General requirements to analysis methods].
Machine-building
X-ray fluorescence energy dispersive general purpose spectrometer BRA-135F
The fist and one of the most important stages of XSFA use is incoming inspection of all the metals and alloys coming the machine-building plant. Unfortunately, this stage is often neglected, and the supplier’s supporting documentation is relied on. Rare mistakes are found only in case of failure of finished item, which leads to significant losses. A typical example thereof is supply of carbon steel pipes to Leningrad mechanical plant in 1979, without incoming inspection of escalator rollers used for manufacture, instead of chromium steel pipes. The mistake was revealed only when several cracking rollers were analyzed.
Similar cases occurred even in aerospace industries of the USA and USSR.
Incoming inspection of alloys may be performed by means of XSFA similarly to the supplier’s marking analysis, or as long as samples of all the alloys used at the enterprises are available, by means of program IDENTIFICATION-W developed in Bourevestnik, Inc. The case when a part of dubious composition has been already included into the finished item is more complicated.
Sometimes portable manual X-ray fluorescence spectrometers based on SSD may be used for composition control of such item, but the most universal method is treating the part with an abrasive paper. Alloy traces remaining on the paper may be compared to those on the paper used for treating a sample steel of the proper grade, using spectrometer BRA-135 and program IDENTIFICATION-W.
Another important task solved by energy dispersion X-ray spectrometers in machine-building is control of coating thickness and composition. Some regulatory documents on the topic are given below:
1. ASTM B568-98(2009). Standard Test Method for Measurement of Coating Thickness by X-Ray Spectrometry.
2. ISO 3497:2000 Metallic coatings -- Measurement of coating thickness -- X-ray spectrometric methods.
3. JIS H 8501-1999 Methods of thickness test for metallic coatings.
Depending on the coating and substrate composition, the coating thickness may be controlled within the range from tenths and hundredths of micron to dozens of microns. An experimental model of the X-ray energy dispersion thickness gauge of gold coatings was manufactured by Bourevestnik as early as in 1974 and tested on gold coatings of one of watchmakers. It turned out that in some cases the coating thickness reached 4 µm instead of 10 µm as per the specification.
General-Purpose X-ray diffractometers DRON-7(M) and DRON-8
The method of seeded directional crystallization has found a wide use in production of turbine buckets for aircraft engines all over the world since it allows producing defect-free single-crystal buckets made of heat-resistant alloys. To analyze the direction of seeds and grown buckets, X-ray diffraction method employing diffractometers DRON-7 and DRON-8 operating in sorting mode has been used successfully.
This method may be used for control of direction of single-crystal casts in machine-building production.
The X-ray diffraction method for analysis of residual stresses in various parts of machines and mechanisms is also wide-spread in machine-building.