4145H Modified Alloy Steel Round Bar, Hot Rolled Steel Bar

4145H Modified Alloy Steel Round Bar, Hot Rolled Steel Bar

Categories:Steel Bars

Model No.:


4145H Modified Alloy Steel Round Bar, Hot Rolled Steel Bar 


AISI 4145 steel is a chromium molybdenum alloy steel grade widely used in the oil and gas sectors. Similar to AISI 4140 but with a higher carbon content. 4145 is more popular in larger diameters due to its increased strength and harden-ability. AISI 4145 steel is commonly supplied quenched and tempered with a hardness of between 30 to 36HRc.AISI 4145 steel is commonly used for a variety of applications in the oil and gas sector. Used often for the manufacture of down hole drilling tools such as drill collars. Other applications include gears, shafts for hydraulic presses, rolls for paper mills, pump shafts and tool holders.

Chemical Composition(%):

0.43-0.490.85-1.100.10-0.350.035 max0.040 max0.80-1.100.25 max0.15-0.25


Mechanical Property Requirements:

Tensile Strength Rm (KSI)Yield Strength R2 (KSI)Elongation(%)Reduction Ration (%)Izod Impact (J)Charp Impact (J)Hardness (HRC)
140 min120 min14 min40 min30-36248-302



Heat treatment temperatures, including rate of heating, cooling and soaking times will vary due to factors such as the shape and size of each AISI 4145 steel component. Other considerations during the heat treatment process include the type of furnace, quenching medium and work piece transfer facilities. Please consult your heat treatment provider for full guidance on heat treatment of AISI 4145 steel.
Annealing: Heat the steel slowly to 800-850°C and allow enough time for the steel to be thoroughly heated. Cool slowly in the furnace to 480°C followed by air cooling.
Stress Relieving: When parts are heavily machined, ground or otherwise subject to cold work, stress relieving will be beneficial prior to hardening.
Hardening: AISI 4145 steel is usually supplied ready heat treated to 30-36HRc. If further heat treatment is required annealed AISI 4145 should be heated slowly to 840-875°C and after adequate soaking at this temperature quench in oil. Temper as soon as the tools reach room temperature.
Tempering: Heat carefully to a suitable temperature selected by reference to a tempering chart or table (usually between 550-700°C, soak at the temperature for 2 hours per 25mm of ruling section, then allow to cool in air. Tempering between 250-375°C is not advised as tempering within this range will seriously reduce the impact values of this steel.

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