1、AWS CAWF 83 W 07842b5 0002032 I W Characterization of Arc Welding Fume AMERICAN WELDING SOCIETY, INC. AWS CAWF 83 I 078Ll265 0002033 3 W Characterization of Arc Welding Fume Research performed by the Mellon Institute Materials Characterization Center, Pittsburgh, Pennsylvania, under contract with th
2、e American Welding Society and supported by industry contributions. Performed By: Edward J. Fasiska Howard W. Wagenblast Margaret Nasta Mellon Institute MCC Pittsburgh, PA 15213 February, 1983 Prepared for: Safety and Health Committee AMERICAN WELDING SOCIETY 550 N.W. LeJeune Road Miami, FL 33126 AW
3、S CAWF 83 W 078i.12b5 000203i.1 5 H . International Standard Book Number: 0-87 17 1-229-6 American Welding Society, 550 N.W. LeJeune Rd., Miami, FL 33126 1983 by American Welding Society All rights reserved This report is published as a service and convenience to the welding industry and is the prod
4、uct of an independent contractor (Mellon Institute) which is solely responsible for its contents, The materials in this report have not been independently reviewed or verified and are only offered as information. AWS assumes no responsibility for any claims that may arise from the use of this inform
5、ation, Users must make independent investigations to determine the applicability of this information for their purposes. Printed in the United States of America AWS CAWF 83 W 078q265 0002035 7 = Co rit en ts Personnel . v Acknowledgements . vii List of Figures . List of Tables . Abstract . I. Introd
6、uction !. II . Sampling Techniques., A . Bulk Samples B . Dispersed Samples . 1 . Nuclepore Filter Samples 2 . Electrostatic Collector . 3 . Sticky Films III . Analytical Techniques and Sample Preparation A . X-ray Diffraction . B . Energy Dispersive X-ray Spectrometry C . Suspended Particulate Eval
7、uation and Classification System 1 . Generation of a Search Grid System . 2 . Detection of Particles Intersecting the Search Grid System . 3 . Size and Shape Analysis of Particles . 4 . Chemical Analysis of Particles D . Transmission Electron Microscopy and Scanning Transmission Electron Microscopy
8、. E . Gas Chromatography-Mass Spectrometry . IV . Results and Discussion., A . Particle Size . B . Particle Chemistry . 1. E6010 . 2 . E7018 . 3 . E7OS-3 . 4 . E70T-1 . 5 . E308-16 6 . E5356 . 5 . Data Reduction and Particle Type Classification V . Siimrna ry . ix ix xi 1 1 1 2 2 2 2 2 2 3 3 3 3 3 4
9、 4 5 6 6 6 7 7 8 8 9 9 10 11 iii Person ne1 AWS Research Committee Dr. A. N. Ward, Chairman K. L. Brown, Vice-Chairman M. E. Kennebeck, Jr., Secretary J. S. Gorski P. W. Ramsey Caterpillar Tractor Company Lincoln Electric Company American Welding Society Kemper Insurance Companies A.O. Smith Corpora
10、tion E. Mastromatteo INCO, Ltd. G.E. Wiggs The Heil Company V AWS CAWF 83 M 078L12b5 O002037 O I Acknowledgements Ken Brown and Kevin Lyttle of the AWS Fumes and Gases Committee. carefully monitored the project, and were ably assisted by Bill DeLong, Al Lesnewich and Gene Wiggs of the Safety and Hea
11、lth Committee. Funds for this project were provided by the American Welding Society. The American Welding Society gratefully acknowledges the financial support of the program by industry contributions, Supporting Organizations Air Products and Chemicals, Incorporated Airco Welding Products Allis-Cha
12、lmers Alloy Rods Division, The Chemetron Corporation AWS Detroit Section AWS New Orleans Section Arcos Corporation The Binkley Company Caterpillar Tractor Company Chicago Bridge and Iron Company Grove Manufacturing Company, Division of Kidde, Incorporated General Electric Company The Heil Company Ho
13、bart Brothers Company Huntington Alloys, Incorporated Lincoln Electric Company Miller Electric Manufacturing Company National-Standard Company A.O. Smith Corporation Teledyne - McKay, Incorporated Trinity Industries, Incorporated Truck Trailer Manufacturers Association Walker Stainless Equipment Com
14、pany Weld Tooling Corporation i Many other organizations have made contributions to support the ongoing program from May 1979 to the present. vii AWS CAWF 83 I 078L1Zb5 0002038 2 U List of Tables 1 . 2 . 3 . 4 . 5a-e . 6a.e . 7a.e . 8a.e . 9a.e . 10. Specific definitions for the Steel Fume Categorie
15、s . 13 Specific definitions for the Aluminum Fume Categories 14 Particle Average Diameters for the Total Fume Sample., 16 Percent Composition of the Steel Weld Fumes . 17 Particle Distribution of the Steel Weld Fumes in Percent by Number . 22 Particle Distribution of the Steel Weld Fumes in Percent
16、by Mass . 27 Average Particle Dimensions for Steel Weld Fumes . 32 Data for the Aluminum Fume 37 Chemical Analysis of Bulk Welding Fume 39 Particle Size Distributions for the Total Fume Sample 15 List of Figures 1a.e . SEM Photographs of Welding Fumes (20. OOOX) . 41 2a-f . Energy Dispersive X-Ray S
17、pectra of the Bulk Welding Fumes . 44 3 . Size Distribution Graph for the E6010 Fume . 47 4 . Size Distribution Graph for the E5356 Fume . 47 5 . Size Distribution Graph for the E7018 Fume . 48 6 . Size Distribution Graph for the E70S-3 Fume 48 7 . Size Distribution Graph for the E70T-1 Fume . 49 8
18、. Size Distribution Graph for the E308-16 Fume . 49 9 . STEM Microanalysis for the E6010 Fume . 50 10 . STEM Microanalysis for the E7018 Fume . 51 11 . STEM Microanalysis for the E70S-3 Fume 52 12 . STEM Microanalysis for the E70T-1 Fume 53 13 . STEM Microanalysis for the E308-16 Fume 54 14 . STEM M
19、icroanalysis for the E5356 Fume . 55 ix Abstract Six welding fumes, representing a variety of welding rods and wires, were analyzed for parti- cle size and chemistry by X-ray diffraction, energy dispersive X-ray analysis, scanning transmis- sion electron microscope, and automated electron beam analy
20、sis. Four carbon steel fumes (E601 O, E7018, E7S-3, E70T-1), a stainless steel fume (E308-16) and an aluminum fume (E53561 were tested. It was found that particle average diameters are all in the respirable range - between 0.1 and 1 .O pM. Few individual particles were greater than 1 p MI but STEM p
21、ictures revealed many particles as small as 0.01 pM. The particles appeared to be spheres or clusters of spheres. Even though no crystalline features were observed, all particles examined produced electron dif- fraction patterns, indicating that they contained crystalline material. There was no corr
22、elation bet- ween average diameter and particle chemistry or between average diameter and fume type. An analysis of particle chemistry indicates that the potential toxicity of the fumes does vary appreciably. xi AWS CAWF 83 07842b5 0002090 O Characterization of Arc Welding Fume I. Introduction Durin
23、g the process of welding, metal vapors are pro- duced in the electric arc. As these vapors cool and solidi, a fume is formed that may be a potential health hazard to the welder and to others working in the same area. Such fine aerosols are all irritating to the respiratory system. Yet some fumes may
24、 potentially be more dangerous than others because of the specific substances present. The purpose of this study is to provide a data base of chemical, crystallographic, and physical data for represen- tative welding fume types which will aid in the understan- ding of the interactions of these parti
25、cles with the human respiratory system. Such interactions are affected by many variables. Therefore, a simple percent weight analysis for various eIements does not provide adequate information since individual particle size and chemistry affect toxici- ty. For example, a few large particles may domi
26、nate a percent by weight analysis. However, if these particles were over 10p.M in diameter, they might not reach the lower respiratory system at all, while compounds present in thousands of fine particles would penetrate to the alveoli of the lungs and could be absorbed into the blood, Parti- cle mo
27、rphology is also significant since particles with sharp edges or fibers are more irritating to the lungs than smooth, sphere-shaped objects. Finally, specific com- pounds must be identified since such factors as crystallini- ty, solubility, and oxidation state affect to-xicity. Such in- formation ma
28、y influence the determination of federal stan- dards for occupational exposure. These objectives were accomplished by using various macro and micro scale techniques. Initially, energy disper- sive X-ray analysis (EDXA) and X-ray diffraction (XRD) were used to obtain background information on bulk fu
29、me properties. The focus of this work was the analysis of the welding fume on a particle by particle basis. Automated electron beam analysis (SPEC) was used to analyze large numbers of particles, and specially designed computer software sorted the particle data by size and chemistry. Finally, a scan
30、ning transmission electron microscope (STEM) was used for a manual examination of a smaller number particles for size, chemical composition, and crystallinity. An examination of all of the data available for a fume can then be used to decide whether tox- icological testing may be advisable. II. Samp
31、ling Techniques Two general types of samples were required for the in- vestigation: bulk fume samples which could be used for the analytical techniques requiring large amounts of sam- ple material, and lightly dispersed samples for the techni- ques which provide analyses of individual particles. A.
32、Bulk Samples The bulk samples were collected by AWS in a conical chamber as described in AWS Fl.1-79, Laboratory Method for Measuring Fume Generation Rates and Total Fume Emission of Welding and Allied Processes. This pro- vides a sample of several grams needed for certain analytical procedures such
33、 as X-ray diffraction. 1 AWS CAWF 83 m 0784265 000204L 2 m 2KHARACTERIZATION OF ARC WELDING FUME B. Dispersed Samples For the analytical techniques which provide data from individual particles of the fume, it is required that the par- ticles be dispersed in such a manner that the individual particle
34、s are not contingent so that individual particle data is not altered by adjacent particles. In principle, this can be accomplished in two ways. One method would be to redeposit portions of bulk samples to provide a non- contingent dispersion. This approach, however, has some danger in that there is
35、no absolute assurance that the redeposition process does not break up naturally occur- ing particle agglomerates, dissolve certain particle types, or lose either large or small particle sizes. The other approach is to collect the particles in a dispersed state on a suitable substrate directly from t
36、he weld fume. The only concern about this approach is that the collection times are necessarily short (a few seconds) and may not accurately represent an 8-hour average. Three direct sampling techniques were investigated in order to determine a method that would reliably sample representative portio
37、ns of the various arc welding fumes. 1, Nuclepore Filter Samples Fume samples were collected by suction (2 liter/min) onto polyester Nuclepore filters (pore size 0.2pM) loaded into standard plastic cassettes. There was some tendency for particles to agglomerate around the pores, but this was not a s
38、erious problem if sampling times were kept relative- ly short and the filter loadings were light. It was most convenient to collect several samples 18 inches above the arc at times such as 1,3, and 5 seconds in order to bracket the optimum filter loadings needed for the various analytical techniques
39、 such as SPEC and STEM. This technique is a standard method for collection of ambient air particulates analyzed in this laboratory. It also appears to be the best method for collecting fume samples defined for characterization of the individual particles rather than by bulk analysis. 2. Electrostati
40、c Collector With this technique, the particles were collected on smooth surfaces such as a glass slide or plastic tape using an electrostatic collector and charge qeutralizer system. Although this technique reduced the tendency of the par- ticles to agglomerate, the method was discarded because some
41、 agglomeration was still observed and because the long sampling tube needed for this instrument may be causing some size and chemical discrimination in parti- cle collection, Further, it was felt that the electrostatic charge neutralizer in the system might be breaking up naturally-occurring agglome
42、rates and, therefore, altering the actual state of the weld fumes. 3. Sticky Films Samples were collected simply by holding a glass slide coated with a very thin film of a sticky substance such as Vaseline directly in the fume. This method was also discarded because the smallest particles are not re
43、presen- tatively collected due to the air stagnation zone that develops at the surface of the slide. Therefore, Method 1, the collection of the fume on Nuclepore filters, was selected as the primary sampling technique. The samples that were collected were compati- ble with the scanning electron micr
44、oscope and the scann- ing transmission electron microscope, the instruments needed to measure size and chemistry of the submicron particles that are characteristic of welding fume. III. Analytical Techniques and Sample Preparation A. X-ray Diffraction (XRD) Portions of the as-received bulk fume samp
45、les were loaded into glass trays to provide a smooth, even surface of the material, The trays were then placed in an X-ray diffractometer and exposed to copper K-alpha radiation over the Bragg reflection angle of 6 degrees to 100 degrees using a focusing graphite crystal, diffracted-beam monochromat
46、or, The output data from an X-ray diffrac- tion analyses typically consists of peaks of different in- tensities at various Bragg reflection angles. These peaks result from the unique structures of crystalline materials with definite relationships of the distances and angles bet- ween the constituent
47、 atoms. Thus, proper indexing of the reflections from an X-ray diffraction pattern will reveal the specific crystalline compounds and phases which are present. It is important to mention that X-ray diffraction will not indicate the presence of amorphous materials or materials with particle sizes les
48、s than approximately 0.03 In the present study, the peaks on the patterns were generally relatively sharp indicating that at least portions of the sample materials were fairly well crystallized. The results of the analyses for the six samples are described in the Discussion Section of the report. PM
49、* AWS CAWF i33 E 07842b5 O002042 4 E Analytical Techniques and Sample Preparation13 B. Energy Dispersive X-ray Spectrometry (EDXA) Portions of the bulk samples were mounted on high purity graphite wafers with Duc0 Cement, coated with 0.02pM of carbon, and examined in the scanning elec- tron micrascope (SEM) using a 24 KV acceleradng voltage and a tilt angle of approximately 45 degrees. The microscope is equipped with an energy-dispersive X-ray analyzer which detects and semi-quantitatively measures all elements with atomic numbers greater than ten. (The elements not detected by EDXA are
