Impact 7 Steel Technical Data A Durable, Dependable Steel Solution For Harsh Environments Alloy Description As a world leader in steel manufacturing, TimkenSteel specializes in providing custom steel solutions to a wide range of industries. One key solution for energy exploration and production is Impact 7 steel. The strength and toughness properties of Impact 7 steel result in enhanced dependability. This helps you achieve a higher return on investment by reducing the need for repairs and replacements. Impact 7 steel has also given the stator tubing used in power sections much improved toughness at ultra-high yield strengths. Lastly, Impact 7 steel has excellent heat-treat response compared to the standard 41 grade of steel. Impact steel meets or exceeds the National Association of Corrosion Engineers (NACE) and American Petroleum Institute (API) standards for resistance to sulfide stress corrosion cracking above 95 ksi. In oil well completion accessories, Impact 7 steel provides a means to survive these hostile environments. Give us a problem, and we ll find the solution. Impact 7 steel is produced using the electric arc-furnace method. After the melting process, the molten steel is transferred to a ladle refiner for alloy adjustments and vacuum de-gassing. By performing inert gas stirring under a near-perfect vacuum, impurities and harmful gases are removed. This melting and refining process path reduces levels of elements such as phosphorus and sulfur. Refining and inclusion engineering practices are controlled to optimize strength and toughness properties in both the longitudinal and transverse directions of the final product. It also enhances resistance to sulfide stress corrosion. After refining the steel, it is teemed into large bottompoured ingot molds or continuously cast into large blooms. These ingots or blooms may be rolled into solid rounds for machining/forging or for conversion into seamless mechanical tubing. Alloy Type Through hardenable. Typical Applications Mud motors, drilling jars, perforating guns, various subs.
Procedure and Results Chemistry C Mn S Si Cr Ni Mo Cu Al V Nb Typical Impact 7 0.28 0.78 0.003 0.27 1.37 0.13 0.69 0.19 0.029 0.008 0.03 Physical Properties Value (Units) Density0.283 lb/in 3 (7.8 g/cm 3 ) Thermal Conductivity 296 BTU-in/hr-ft²- F (42.7 W/m-K) Specific Heat 0.114 BTU/lb- F (0.48 J/g-K) Thermal Expansion Coefficient 7.2μin/in- F for -0 F (13 μm/m-k for -0 C) Modulus of Elasticity29.7x10 3 ksi (5GPa) Poisson s Ratio 0.29 Mechanical Properties Hardness Value (Units) See Figure 1 for tempering curve Tensile Properties See Figure 2 and Figure 3 Charpy Impact Fracture Toughness See Figure 4 Fatigue See Figure 5 Heat Treatment As hot rolled Temperatures ( F/ C) Normalize 10-10ºF/8-925ºC Anneal Quench and Temper Forge at 20ºF (10ºC) maximum, do not forge below 10ºF (8ºC) 1500-10ºF/815-8ºC, slow cool Austenitize at 10ºF to 10 F, (8ºC to 930ºC), quench in oil or water, temper at 930ºF to 1325ºF (500ºC to 7ºC)
Hardenability Typical jominy hardenability is plotted in Figure 6 and compared to 41 steel. Workability Weldability Hot Forgeability Similar HAZ hardening to 41 in welding response, but with less propensity to crack during welding. Commonly friction welded for tool joints. Similar to 41 material (10ºF 2250ºF, 8ºC 1230ºC) Tensile Strength At Service Temperatures Corrosion Resistance High Temperature Properties See Figure 7 and Figure 8
45 Tempering Temperature (ºC) 500 550 0 650 0 45 Rockwell C Hardness 35 30 25 35 30 25 900 1000 0 10 1300 Tempering Temperature (ºF) Figure 1 Tempering Curve. Material hardened at 10 F, water quenched, and tempered for 1.5 hours. Lab generated curve with 0.7" stock. 1 Tempering Temperature (ºC) 0 650 0 Strength (ksi) 1 150 1 130 1 0 1000 900 800 Strength (MPa) 100 Ultimate Tensile Strength 0 Yield Strength 90 1050 0 1150 10 1250 1300 1350 Tempering Temperature (ºF) Figure 2 Ultimate Tensile Strength and Yield Strength. Production material was austenitized at 10ºF, water quenched, and tempered between 1075ºF and 1325ºF for approximately minutes. Tubes range in size from 12.25" OD to 3.375" OD with wall thicknesses ranging from 2.125" to 0.42."
80 Tempering Temperature (ºC) 0 6 6 6 680 0 7 Elongation (%) Reduction in Area (%) 80 Elongation (%) 24 28 24 Elongation (%) Figure 3 16 0 1150 10 1250 1300 1350 Tempering Temperature (ºF) Elongation and Reduction in Area. Production material was austenitized at 10ºF, water quenched, and tempered between 1075ºF and 1325ºF for approximately minutes. Tubes range in size from 12.25" OD to 3.375" OD with wall thicknesses ranging from 2.125" to 0.42." 16 Testing Temperature (ºC) -80 - - - 0 Charpy Impact Energy (Ft-Lbs) 100 90 80 50 30 Transverse Longitudinal -100-50 0 50 100 150 Testing Temperature (ºF) y = ksi uts = 1ksi Figure 4 Charpy Transition Curve. Austenitized at 15ºF and tempered at 10ºF for 45 minutes. Production heat treated samples from 1.0" wall tubing. 1 130 1 100 90 80 50 Charpy Impact Energy (J)
Stress at Failure (KSI) Figure 5 Cycles 10 4 150 10 5 10 6 10 7 10 8 1 = 149 KSI y 1000 = 161 KSI 950 130 1 100 90 80 500 10 4 10 5 10 6 10 7 10 8 Cycles Fatigue Strength. Austenitized at 10 F, water quenched, and tempered at 11 F for 1.5 hours. Lab generated data from 0.7" stock. R.R. Moore rotating bending fatigue samples. R = -1. uts 900 850 800 750 0 650 0 550 Stress at Failure (MPa) Hardness (HRC) 58 56 54 52 50 48 46 44 42 38 36 Position (mm) 0 10 30 50 Impact 7 41 0 5 10 15 25 30 35 Jominy Position (1/16 th of in.) 58 56 54 52 50 48 46 44 42 38 36 Figure 6 Jominy hardenability from production data.
1 135 130 Testing Temperature (ºC) 0 50 100 150 0 250 RT y RT uts = 1 KSI = 134 KSI 950 900 Strength (KSI) 125 1 115 105 Ultimate Tensile Strength Yield Strength 100 0 100 0 300 0 500 Testing Temperature (ºF) 850 800 750 0 Strength (MPa) Figure 7 Ultimate Tensile Strength and Yield Strength at Elevated Testing Temperatures. Austenitized at 10 F, water quenched, and tempered at 1285 F for 65 minutes. Production heat treated samples from 1.438" wall tubing. 75 65 Testing Temperature (ºC) 0 50 100 150 0 250 % Reduction RT y RT uts = 1 KSI = 134 KSI 75 65 Ductility 25 25 Ductility % Elongation 15 0 100 0 300 0 500 Testing Temperature (ºF) 15 Figure 8 Elongation and Reduction in Area at Elevated Testing Temperatures. Austenitized at 10 F, water quenched, and tempered at 1285 F for 65 minutes. Production heat treated samples from 1.438" wall tubing.
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