Volume 09 - Metallography and Microstructures Part 5 pot

Fig. 22 ASTM A335, Grade P5, seamless steel pipe, 4.75-in. OD by 5 8 - in. wall. Annealed by austenitizing at 900 °C (1650 °F) for 1 h and furnace cooling. Specimen was taken at midwall thickness. Alloy carbide in a ferrite matrix. Nital. 500× Fig. 23 ASTM A335, Grade P7, seamless steel pipe, 5.563-in. OD by 0.375- in. wall, fully annealed. Specimen was taken in longitudinal direction. S tructure is fine ferrite grains (white) with a dispersion of alloy particles. Vilella's reagent. 100× Fig. 24 ASTM A335, Grade P11, seamless steel pipe, 5.563-in. OD by 0.375- in. wall, fully annealed. Specimen was taken in longitudinal direction. Light areas are ferrite; dark areas are pearlite containing some Widmanstätten plates of ferrite. Nital. 500× Fig. 25 ASTM A335, Grade P22, seamless steel pipe, 1.312-in. OD by 0.25- in. wall, hot drawn and annealed by austenitizing at 900 °C (1650 °F) for 1 h and furnace cooling. Structure consists of a fine dispersion of alloy carbide particles in a matrix of ferrite. Nital. 550× Fig. 26 ASTM A381, Class Y52, gas metal arc welded steel pipe, 36-in. OD by 0.406- in. wall, fully annealed. Light areas in the structure are ferrite; dark areas are pearlite; some nonmetallic stringers are present in the ferrite (toward the top of the micrograph). 2% Nital. 100× Fig. 27 ASTM A161 seamless steel tube, 5-in. OD by 7 16 -in. wall, as hot draw n. Specimen from midthickness of wall in longitudinal section. Structure is ferrite and pearlite (dark). Nital. 110× Fig. 28 ASTM A200, Grade T5, seamless alloy steel tube, annealed. Longitudinal section. Structure is a fine dispersion of alloy carbide in a matrix of ferrite (light background). Vilella's reagent. 100× Fig. 29 Same specimen as shown in Fig. 28, but a t a higher magnification. Light areas are ferrite; black particles are alloy carbide, located mostly within the ferrite grains. Vilella's reagent. 500× Fig. 30 Same specimen as shown in Fig. 28 and 29 , but at a still higher magnification. Black constituents are alloy carbide; matrix is ferrite. Vilella's reagent. 1000× Fig. 31 ASTM A209, Grade T1, seamless alloy steel tube, hot finished and annealed. Ferrite (light) and pearlite; some banding. Nital. 100× Fig. 32 Same steel as Fig. 31 , but cold drawn and stress relieved. Micrograph from longitudinal section. Ferrite and pearlite (see also Fig. 33). Nital. 100× Fig. 33 Same specimen as shown in Fig. 32 , but at a higher magnification. The light areas in the structure are ferrite, and the dark areas are pearlite. Nital. 500× Fig. 34 ASTM A213, Grade T5c, steel tube, hot finished to a 2-in. OD by 0.22- in. wall, held at 730 °C (1350 °F) and air cooled. Dispersed chromium and titanium carbides in ferrite. Vilella's reagent. 100× Fig. 35 Same specimen as shown in Fig. 34 , but at a higher magnification. The carbide particles are more completely resolved. The small dark areas are titanium carbide. Vilella's reagent. 500× Fig. 36 Copper brazed joints (outlined white bands) in spiral- wound tubing made from ASTM A254, Class I, steel. Specimen is a cross section. Structure is mostly ferrite. 2% Nital. 100× Fig. 37 1015 steel tube, resistance welded without filler metal. Vertical band through the center is the fusion zone; heat-affected zones are on each side. Transverse section. Nital. 100× Fig. 38 Same as Fig. 37 , except that the tube has been normalized. Light areas are ferrite; dark areas, pearlite. Weld zone is at center. Note general uniformity of structure. Nital. 100× Fig. 39 Same as Fig. 38 , except the tube has been cold drawn (note elongated grains). A longitudinal section that was taken near the weld zone. The structure of the weld is the same as the base steel. Nital. 100× Fig. 40 Same as Fig. 39 , but specimen is transverse to the direction of the weld. The tube has been normalized and cold drawn after welding. Structure is ferrite (light constituent) and pearlite (dark constituent). Nital. 100× Fig. 41 Same as Fig. 40 , except the tube has now been renormalized after cold drawing. Structure is equiaxed ferrite and pearlite. Renormalizing apparently caused some coarsening of the grains (compare with Fig. 38 ). Nital. 100× Fig. 42 Same as Fig. 39, except after normalizing, cold drawing, and renormalizing. Specimen is longitudinal. Note equiaxed ferrite grains. Nital. 100× Fig. 43 1018 steel tubing, showing a transverse section near the longitudinal seam after we lding and normalizing. Note flow pattern. Nital. 100× Fig. 44 Aluminate inclusion (longitudinal) in 1025 cold drawn steel tube. As-polished. 500× Fig. 45 Segmented sulfide inclusion (longitudinal) in 1215 cold drawn steel tube. As-polished. 1000× Fig. 46 4140 steel tube, annealed by austenitizing at 845 °C (1550 °F), for 3 h, furnace cooling to 620 °C (1150 °F), and air cooling to room temperature. Structure is ferrite and pearlite. Nital. 1000× Fig. 47 4140 steel tube, austenitized at 830 °C (1 525 °F) for 1 h, oil quenched, tempered at 595 °C (1100 °F) for 2 h. The structure consists of some ferrite (white) in tempered martensite. Nital. 1000× Fig. 48 Silicate (black) and sulfide (gray) inclusions in 4620 steel tube. As-polished. 500× Fig. 49 Decarburization at the surface of 5048 steel seamless tube (transverse). Nital. 100× Fig. 50 Large silicate inclusion (longitudinal) in 8620 steel tube. As-polished. 250× Carbon and Low-Alloy Steel Castings: Metallographic Techniques and Microstructures Introduction CARBON AND LOW-ALLOY STEEL CASTING specimens are prepared using the techniques described in the article "Carbon and Alloy Steels" in this Volume. Sectioning. As-cast and heat-treated steel castings are usually soft enough to permit sawing or hollow boring for initial extraction of test pieces. The oversize pieces are then sawed or abrasive-wheel cut to specimen size. If the casting is hard, abrasive-wheel cutting is used. Precautions must be taken against overheating during cutting. Even with the application of copious water, it is possible to overheat the piece being sectioned. Section thickness in a single steel casting can vary from a fraction of an inch to many inches, resulting in different cooling rates and thus in different microstructures within ascast and heat-treated castings. Therefore, for complete examination of a casting, several specimens may have to be extracted. Some of the micrographs in this article compare the structures observed in sections of different thicknesses (see Fig. 4, 5, and 6 in the section "Atlas of Microstructures for Carbon and Low-Alloy Steel Castings" in this article). Mounting. Bakelite is often used for mounting specimens. The microstructures of most steel castings are not affected by the thermosetting temperature of Bakelite. In some foundry laboratories, cold-mounting materials (described in the article "Mounting of Specimens" in this Volume) are used more often than Bakelite. [...]... low-alloy steel castings Microstructures of Carbon and Low-Alloy Steel Castings The microstructures presented in this article are those of carbon and low-alloy steel castings in the as-cast, annealed, normalized, normalized and tempered, and quenched and tempered conditions in 2 5- mm (1-m.), 7 5- mm (3-in.), and 150 mm (6-in.) thick sections Stainless steel castings, austenitic manganese steels, and heat-resistant... tempered at 56 5 °C (1 050 °F) for 2 h, air cooled Structure consists of tempered martensite-bainite 4% nital 50 0× (L.L Bright) Fig 44 Low-alloy cast steel (0.28C-0 .55 Mn-1.3Si-1.00Ni-1.5Cr-0.4OMo), normalized at 9 25 °C (1700 °F), hardened by water quench from 900 °C (1 650 °F), and tempered at 290 °C (55 0 °F) to ~50 0 HB Tempered martensite with some bainite 2% nital 100× (D Subramanyam) Fig 45 Low-alloy cast... for Fig 19, 150 mm (6 in.) thick, quenched and tempered Austenitized at 900 °C (1 650 °F) for 3 h to temperature and held 5 h, water quenched, tempered at 59 5 °C (1100 °F) for 4 h to temperature and held 6 h, air cooled Very fine ferrite and spheroidized pearlite 5% nital 100× Fig 21 ASTM A148 steel, grade 10 5- 8 5 (0.27% C, 0.80% Mn, 0 .51 % Si, 0. 35% Mo), 150 mm (6 in.) thick, quenched and tempered Austenitized... grade 7 0-3 6 0. 35 max 0.70 max 0.80 max 0. 05 max 0.06 max Al 28, grade B-3 1.1 2-1 .28 11. 5- 1 4.0 1.00 max 0.07 max A148 Specification sets mechanical-property limits A216, grade WCA 0. 25 max 0.70 max 0.60 max 0.04 max 0.0 45 max (b) A216, grade WCB 0.30 max 1.00 max 0.60 max 0.04 max 0.0 45 max (b) A 352 , grade LC3 0. 15 max 0 .5 0-0 .80 0.60 max 0.04 max 0.0 45 max 3-4 Ni (a) Where not specified by ASTM number,... ASTM A128 1.11 12.8 0.20 0.0 25 0 .54 0.05P 0.006S rem ASTM A128 grade A 1. 25 12.9 0.66 0.06 0. 05 rem ASTM A128 grade C 1. 35 12.98 0.28 0.0 25 2.06 rem ASTM A128 grade D 0.88 12.86 0.83 0.026 0.82 3.77Ni 0.026P rem ASTM A 128 grade E2 1 .09 13.9 0.67 0. 055 2.00 0.032P rem Experimental alloy 1.76 10 .5 0 .55 2 .5 0.70 0.016P rem References cited in this section 1 Y.N Dastur and W.C Leslie, Mechanism... steel castings are intended for pressure-containing parts suitable for service to -1 15 °C (-1 75 °F) Ferritic castings are normalized and tempered or liquid-quenched and tempered (Fig 41) before being placed in service The one martensitic grade, CA6NM, in ASTM A 352 should be heated to 955 °C (1 750 °F) minimum and air cooled to 95 °C (200 °F) maximum prior to any optional intermediate temper This grade, however,... (globular) 2% nital 50 0× Fig 34 Same steel as for Fig 33, 150 mm (6 in.) thick, normalized by austenitizing at 9 25 °C (1700 °F) and air cooling Structure: fine and coarse pearlite in a coarse-grained ferrite matrix 2% nital 50 0× Fig 35 Same steel as for Fig 33, 150 mm (6 in.) thick, in the as-quenched condition Austenitized at 9 25 °C (1700 °F) and oil quenched Pearlite (dark), randomly dispersed in... structure and grain size 4% nital Fig 38 ASTM A487 steel, class 2, 25 mm (1 in.) thick, normalized by austenitizing at 900 °C (1 650 °F) and air cooling The structure consists of pearlite and ferrite See Fig 39 and 40 for influence of alternate heat treatment and section size 4% nital 250 × Fig 39 ASTM A487 steel, 25 mm (1 in.) thick, normalized by austenitizing at 955 °C (1 750 °F) for 3 h, held 5 h, air... °C (1 650 °F) for 6 h and air cooling The microstructure consists of lamellar pearlite (gray and black) and ferrite (white) Nital 250 × Fig 14 Same steel as for Fig 8, 150 mm (6 in.) thick, quenched and tempered Austenitized at 900 °C (1 650 °F) for 6 h, water quenched, tempered at 620 °C (1 150 °F) for 6 h Structure is fine pearlite and ferrite (white) Nital 250 × Fig 15 ASTM A148 steel, grade 9 0-6 0 (0.30%... Picral: 4 -5 g picric acid, 95 mL ethanol or methanol, and 5 mL distilled H2O Immerse 20 s or more if necessary Rinse thoroughly in alcohol and dry Cyclic etch: 3% nital, 10% HCl solution, and 2% NH4OH (ammonium hydroxide) solution Alternate immersion in nital and 10% HCl for 15 s Rinse specimen in alcohol and dry between solutions Repeat 2-3 times, then immerse in NH4OH 15 s Rinse in alcohol and dry . normalized and tempered, and quenched and tempered conditions in 2 5- mm (1-m.), 7 5- mm (3-in.), and 15 0- mm (6-in.) thick sections. Stainless steel castings, austenitic manganese steels, and heat-resistant. ferrite. Nital. 50 0× Fig. 25 ASTM A3 35, Grade P22, seamless steel pipe, 1.312-in. OD by 0.2 5- in. wall, hot drawn and annealed by austenitizing at 900 °C (1 650 °F) for 1 h and furnace cooling vary from 55 0 to 17 95 MPa (80 to 260 ksi) and minimum yield strengths from 2 75 to 1 450 MPa (40 to 210 ksi) for the 14 grades in A 148. Figures 15, 16, 17, 18, 19, 20, and 21 illustrate microstructures