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Analysis of Ferrous Base Thermo Scientific ARL PERFORM’X 4200 Advanced WDXRF Spectrometer

• Girders, all kinds of bridge and structural sections

• Wires, nuts, bolts and forgings of almost any description

• Springs, cutting steels

From a compositional point ofview, these steels can be distinguishedby the fact that the alloying elementsgenerally total less than 5-7 %.Typically, the main alloyingelements are present at less than thefollowing concentrations: Mn 2 %; Cr 3 %; Ni 5 %; Cu 1.5 %; Mo 1.5 %; V 1 %.

High alloy steels High alloy steels contain, in additionto iron and carbon, notablequantities of one or more of thefollowing elements: nickel,chromium, manganese, silicon,cobalt, tungsten, molybdenum andvanadium. Included under thisheading are: • Stainless steels of types such as

18/8, austenitic, maraging, martensitic and all types of specialstainless steels

• Tool steels • High speed steels • High manganese steels

Instrument parameters and conditionsThe Thermo Scientific ARLPERFORM’X 4200 XRFspectrometer can be calibrated usingcommercially available standards orwell analyzed samples from the user.It should be stressed that an XRFspectrometer is a very accuratecomparator, but the accuracy of thefinal analysis is entirely dependent onthe quality of the standards used forcalibration.

Typical performance in low alloy samplesTable 1 gives a summary of analyticalresults obtained using a set ofinternational standards with bestparameters in regards to crystal,detector, collimator and power.Limits of detection (LoD) weredetermined using 100 seconds perelement counting times.

Application Note: AN41655

Key Words

• ARL PERFORM’X

• Ferrous base

• XRF

• X-ray fluorescence

IntroductionFerrous base materials areimportant products in metalsindustry as they are the foundationin many applications such asbuilding, automotive and manymanufacturing processes. It istherefore important to be able toaccurately analyze these materials toconfirm compliance with theirchemical specifications and allowfor high quality and efficientproduction.

There are several kinds of ironswhich are distinguished by theircomposition and use. They belongto two main categories: • Pig irons (hot metal), forming

the basic production for the manufacture of steel

• Cast irons, used for theproduction of semi-manufactured products

From a metallographic point ofview, a distinction can be madebetween white cast iron with acementite structure and grey castiron which contains free graphiteeither in the form of laminae ornodules. These make grey cast ironinhomogeneous and thereforedifficult to analyze. Alloy cast ironsalso exist where alloying elementssuch as nickel, chromium,manganese, copper, etc. are addedto improve hardness, corrosionresistance or engineering properties.

Low alloy steels This category covers steels whichare destined for a wide variety ofuses, such as the production of: • Steel castings, rails, axles, boiler

and ship plates, automobile bodies

Table 1: Typical limits of detection

Element Line LoD (ppm)Al Kα 3.2Si Kα 1.9P Kα 1.1S Kα 0.7Ti Kα 0.9V Kα 0.9Cr Kα 1Mn Kα 1.6Co Kα 4Ni Kα 2.4Cu Kα 2Ta Lβ 5.7W Lα 4As Kβ 7.2Pb Lβ 3Zr Kα 1.3Nb Kα 1.2Mo Kα 1.3Sn Kα 7.3Sb Kα 8.7

AN41655_E 04-11C_130411_MBS/APN/2 13.04.11 15:22 Seite 1

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AN41655_E 04/11C

Typical stability testA stability test consisting of severalruns on a typical sample over 12days was performed. Each elementwas analyzed using 100 seconds perelement.

The stability of an instrumentreflects the precision that can beobtained. It should be noted thatthe accuracy of the instrument isdependent upon the accuracy of thestandards used to calibrate theinstrument. The stability for eachelement is given in table 2 alongwith the concentration of theanalyte in our test sample.

Typical UniQuant standard-lessanalysisAs in many real life cases, obtainingany or enough standards to create acalibration is not always possible.Or you may receive a sample that isnot flat and/or does not encompassthe entire diameter of the samplecassette. In such situations, we canoffer the most comprehensivestandard-less software package onthe market to solve these uniqueissues: Thermo Scientific UniQuantpackage.

The UniQuant package is afactory calibration based on 64pure element standards that allowsfor concentration determination ofunknown samples in any matrix,size or shape by using complexmathematical algorithms. Thesealgorithms correct for matrix effectsas well as inter-elemental effects toprovide a highly accurate andprecise result.

As can be seen in table 3 thesamples can be measured either as bulk metallic piece (with amaximum diameter of 52 mm) or as drillings (Figure 1). UniQuant is capable of good quantification in both instances.

Thermo Fisher Scientific (Ecublens) SARL,Switzerland is ISO certified.

Table 2: Long term stability test over 12 days

Element Line Concentration Standard Deviation (ppm) (ppm)

P Kα 432 1.1S Kα 340 0.9Al Kα 840 2.6Ti Kα 959 1Cr Kα 3034 1.6Ni Kα 6164 4.1Cu Kα 5243 3.5As Kα 980 4.1Nb Kα 3082 1.9Mo Kα 795 1.1Sb Kα 179 3W Lα 2139 3.8Pb Lβ 55 1.2Ta Lβ 2207 4.8

Table 3: UniQuant analysis on bulk sample and drillings – parenthesis indicate noncertified values

Element Chemical UniQuant as bulk UniQuant as 159 mg % sample % drillings %

W 14.2 14.04 13.99Cr 3.56 3.73 3.79V 0.52 0.524 0.507Mn 0.29 0.3 0.32Mo 0.22 0.223 0.298Co 0.21 0.194 Not foundNi (0.19) 0.163 0.133Cu (0.1) 0.0975 0.022S 0.027 0.0504 0.341Sn (0.035) 0.049 0.027Si 0.14 0.039 0.526P 0.021 0.015 0.077Ti (0.0057) 0.0037 0.0154

ConclusionIt is seen that analysis of irons andsteels can be performed with easeusing the ARL PERFORM’Xsequential XRF spectrometer. Theprecision and accuracy are excellentin these matrix types for routine orR&D analysis.

Furthermore, operation is madeeasy through the new state-of-the-art OXSAS software which is ableto operate with the latest MicrosoftWindows® 7 package.

Figure 1: 159 mg of steel drillings analyzedwith UniQuant

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