Presentation on theme: "Analysis of steel and alloys has been a routine affair since hundreds of years. Although most of the methods are documented by ISO, ASTM and BIS, it is."— Presentation transcript:
Analysis of steel and alloys has been a routine affair since hundreds of years. Although most of the methods are documented by ISO, ASTM and BIS, it is still a test to any existing testing laboratory to authenticate the results. In one study , Inter-laboratory Comparison – ILC, data was obtained from 67 laboratories in 31 countries for LAS using certified reference materials (CRM) or SM. In another study , only manganese (Mn) was analyzed on FAAS in different SS and Al A CRM s which are in agreement with the certified values. Normally for the analysis of stainless steel (SS), low alloy steel (LAS), aluminium alloy (Al A), brass and white metal, standard methods are employed wherein gravimetric, titrimetric and Flame Atomic Absorption Spectroscopy (FAAS) are used [3-6]. These are generally cumbersome, tedious and laborious to use. All the analysts have to be trained by quality control personnel. Analysis of each of the steel or alloy sample becomes a matter of concern and skill. Hence, every laboratory has to prove its competency for testing these materials. Therefore, Inter Laboratory Comparison (ILC) in a particular area around a testing laboratory is advisable, when they are analyzed in large quantities. Validation of method for the analysis of steels and alloys G.Swarnabala 1 *, N.Saraswati 2, Y.Praveena 2 Validation of method for the analysis of steels and alloys G.Swarnabala 1 *, N.Saraswati 2, Y.Praveena 2 Challenges: Authentication of sample preparation technique Procurement of Standard Materials (SM) Conducting an Inter-laboratory Comparison (ILC) for some procured samples Validation of the entire method of analysis on ICP-OES  Tatjana Drglin, Mater; Technology, 35(6), 343-345, (2001).  Mohammad Ali Taher; Indian Journal of Chemistry, 43A, 1249-1252 (2004).  Indian Standard-Methods for Chemical analysis of steels, IS: 228 (part 5 - 9)-1987 (reaffirmed 1997), 3rd Ed, BIS, New Delhi, India, (1997-2004).  IS: 504 (parts 2 to 7): 2002, 3rd Ed, BIS, New Delhi, India, (2002).  IS 1608:2005, ISO 6892:1998, BIS, New Delhi, India, (2005).  IS 1501:2002, ISO 6507-1:1997, BIS, New Delhi, India. For SS, LAS, Al alloy and Cu alloy - the chemical analysis and mechanical analysis - the tensile strength, Vickers hardness; conducted for ILC, in a total of 6 laboratories, were found to be satisfactory. Few questionable results and outliers were found which were intimated to the individual laboratories separately. The results of the z-score of all the chemical testing parameters were found to be in the acceptable limit of < ±2.0. The results of method validation and ILC were compared with the supplied certificate of analysis for compliance. It may be emphasized that acid dissolution followed by ICP-OES using SM was an authentic way of analysis and was similar to the available methods. I n the case of SS samples alone, classical methods for nickel (Ni) by gravimetric, chromium (Cr), phosphorus (P) & sulfur (S) by titrimetry were performed. The method was validated with repeatable and reproducible results on ICP-OES using Certified Reference Materials (CRM’s) (since primary standards cannot be used for such measurements). One sample for chemical analysis and two samples for mechanical analysis were distributed from the same lot to all 6 participating laboratories. Experimental Results & Discussion Certified Reference Materials Or Standard Materials ICP-OES- Inductively Coupled Plasma Optical Emission Spectrometer Steel sample TABLE 2 : Method Validation data for Stainless steel ElementsTrue value *(%) Classical (%) Stand Devi (SD) ICP-OES Mean (%) Repeat Mean SD x 10 -3 Reprod mean SD X 10 -2 Mn1.311 + 0.013Nil 1.311.20.24 Mo2.776+ 0.021Nil 2.772.961.48 V0.0346 +0.0016Nil 0.030.213.63 Cr17.84 + 0.0517.820.0217.865.173.77 Ni10.20+ 0.0510.170.00610.2043.165.92 P0.0105 + 0.00050.0090.0010.010.180.04 S0.0069 + 0.00050.00540.0004--- Si0.48+ 0.0070.520.03--- *Certified values for the CRM/SM No: 466/2 TABLE 3 : Method Validation data for Low Alloy Steel ElementsTRUE value*(%) ICP-OES mean (%) Repeat Mean SD x 10 -3 Reprod Mean SD x 10 -3 Al0.046 +0.0040.04640.350.154 Cr1.684 +0.0091.68423.253.94 Cu0.436 +0.0070.43640.133.19 Mn0.419 +0.0060.41920.351.92 Mo0.432 + 0.010.43220.000663.41 Ni2.07 + 0.032.07580.002161.44 P0.074 + 0.0030.07420.000240.24 V0.44 +0.020.44130.000681.66 Si0.2+1.101.97-classical- *Certified values for the CRM/SM No: 410/2 TABLE 4 : Method Validation data for Aluminium alloy ElementsTRUE values *(%) ICP-OES Mean Values (%) Repeat Mean SD x 10 -3 Reprod Mean SD x 10 -3 Fe 0.730 +0.0590.74922.393.11 Mg 0.298 +0.02 0.3504 0.26 0.30 Cu 2.180 +0.104 2.05244.025.54 Mn0.180 +0.0130.17030.220.33 Ni0.130 +0.011 0.1203 0.26 0.27 Zn0.470 +0.0280.48080.532.92 Si Measured 0.74+0.02 0.890- classical -- *Certified values for the CRM/SM No: 216/3 (5% Cu and Al alloy) TABLE 5 : Method Validation data for Brass powder ElementsTRUE values *(%) ICP-OES Mean Values (%) Repeat Mean SD x 10 -3 Reprod Mean SD x 10 -3 Al2.22 + 0.042.22080.603.06 Mn0.86 + 0.030.86771.002.34 Ni0.56 + 0.020.56342.201.36 Pb0.35 + 0.020.35040.260.30 Sn0.70 + 0.050.700730.274.83 *Certified values for CRM/SM –brass powder: 325 mesh lot No: H18P19 TABLE 6 : Method Validation data for White metal ElementsTRUE values *(%) ICP-OES Mean Values (%) Repeat Mean SD x 10 -3 Reprod Mean SD x 10 -3 Bi 0.11 +0.030.1097 0.21 0.50 X 10 -3 Cd 0.14 +0.010.1406 0.25 0.29 X 10 -3 Cu4.58 +0.084.58402.663.14 X 10 -3 Fe0.024 +0.020.02430.340.40 X 10 -3 Ni0.17 +0.030.17040.352.06 X 10 -3 Pb3.18 +0.063.18543.892.72 X 10 -2 Sb9.45 +0.089.45415.541.16 X 10 -2 Zn0.040 +0.0030.04030.220.27 X 10 -3 *Certified values for the CRM/SM No: 178/2 (Tin based) TABLE 1 : Parameters analyzed for all categories of steels & alloys. S.NoSteel/AlloyElements Analyzed 1 Stainless steel (SS) Chromium (Cr), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Phosphorus (P), Vanadium (V), Silicon (Si) Sulphur (S) 2 Low Alloy steel (LAS) Chromium (Cr), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Phosphorus (P), Vanadium (V), Silicon (Si) Aluminium (Al), Copper (Cu) 3 Copper Alloy (Brass, White metal) Copper (Cu), Iron (Fe), Manganese (Mn), Nickel (Ni), Zinc (Zn) Aluminium (Al), Cadmium(Cd), Tin (Sn), Lead (Pb) 4 Aluminium Alloy Copper (Cu), Iron (Fe), Manganese (Mn), Nickel (Ni), Zinc (Zn) Magnesium (Mg) MECHANICAL PROPERTIES Universal Tensile Strength (UTS) and Hardness A z-score evaluation I.Satisfactory: <2 for all elements II. Questionable: 2 3 for all elements III.Outlier: Z> 3 for all elements.