410 Stainless Steel Heat Treatment

410 in the martensitic stainless family

410 is the lowest carbon grade in the 12 percent chromium martensitic stainless family. Chromium at 11.50% is what puts the grade in the stainless family and holds the corrosion resistance, while carbon at 0.15% is the lowest figure in that family and it is the one that sets the hardness ceiling. A quenched part comes out of the cycle at roughly 220 Brinell, which is about 20 HRC, so the grade is taken for parts that need corrosion resistance together with moderate strength and good machinability. It is not a cutting edge steel, and where a die or a blade has to hold 50 HRC or more the carbon has to come from a higher grade such as 420, 440A, 440B or 440C, which start at 0.35% and climb from there.

The card is shop reference information rather than a specification. It prints one preheat step, one hardening temperature and two quench media, then a tempering table in Brinell hardness with a single figure on each row and no tolerance band anywhere. A first run of parts from a new heat of steel is worth treating as a trial before the cycle goes onto production work.

Chemistry of 410

Elements the reference card lists, percent

Source, heat treating reference information for type 410 stainless steel, printed page 200.

The card prints one figure for each element rather than a specification range. Molybdenum, vanadium and tungsten are listed on the card with no figure against them, so those rows are left out of the table instead of being printed as blanks. Phosphorus and sulfur are printed as maxima.

Chromium at 11.50% is the element the corrosion resistance rests on and the one that forms the passive layer. Carbon at 0.15% is the lowest figure in the martensitic family, and it is the reason the hardness ceiling sits close to 220 Brinell. Manganese at 1.00% and silicon at 1.00% are printed as single figures as well. Sulfur at 0.03% is low because 410 is a general purpose grade rather than a free machining one, and a shop that wants the chips to break up is looking at 416, which is the same base analysis with sulfur raised to 0.15%. Phosphorus at 0.04% and sulfur at 0.03% are printed as maxima. Molybdenum, vanadium and tungsten are listed on the card with no figure against them, so those rows are left out of the table. Composition data in the table is for general reference only, actual values vary by standard, mill and heat number, so confirm the figures against the material test certificate of the heat or ask Aobo Steel.

Hardening 410

Preheat, hardening temperature and quench

Source, heat treating reference information for type 410 stainless steel, printed page 200.

The card prints one preheat step, one hardening temperature and two quench media for the grade, with no section size condition against any of them, so the figures stand for the load as written.

The load goes in at 1200 °F (650 °C) for the preheat and then up to 1850 °F (1010 °C) for austenitizing, followed by an air or an oil quench. Air is the slower of the two media and the one to take on thin sections where distortion has to be held down, while oil is used where the section is heavy enough to need faster cooling. A 410 part leaves the quench at about 220 Brinell whichever of the two media is used, because the carbon content is too low for the quench to build much hardness, and that is the figure to keep in mind while the grade is being chosen. One hardening temperature is printed, so a shop running a different austenitizing window is working outside what the card gives.

Tempering response of 410

Hardness left by each tempering temperature

Source, heat treating reference information for type 410 stainless steel, printed page 200.

The card prints 220 BHN for the as quenched condition, the same figure the table repeats at every step from 300 °F to 700 °F. The hardness is printed in Brinell on the card rather than in Rockwell C, and no tolerance band appears against any row.

The tempering line is flat across the lower half of the table. Every step from 300 °F (150 °C) to 700 °F (370 °C) leaves 220 BHN, which is the figure the card prints for the as quenched condition as well, so that part of the table buys stress relief and toughness rather than any loss of strength. Above 700 °F the figures move the other way, 230 BHN at 800 °F (425 °C) and 239 BHN at 900 °F (480 °C), which is where chromium carbides come out of solution and the tempering curve picks up a small secondary hardening response. At 1000 °F (540 °C) the reading drops to 185 BHN, the lowest on the card, and that is the point where the temper has gone past the range a part keeps its strength in. The card prints one figure on each row and says nothing about the number of tempering cycles, so treat the line as the response of the grade and settle the cycles with your heat treater before the parts go into service.

Related reference data

410 is the base of the martensitic stainless family, and the grades above it in carbon are set out on the 420 stainless steel heat treatment page, the 440A stainless steel heat treatment page and the 440B stainless steel heat treatment page. The supply condition of the stainless grade we hold is on the 420 stainless steel page, mechanical property rows for 410 and 416 sit on the martensitic stainless steel properties chart, and chemistry for every grade is on the stainless steel composition chart. Tempering bands across the tool steel groups are on the tool steel tempering chart.

Reference data compiled from Heat Treatment, Selection, and Application of Tool Steels (William E. Bryson, second edition, Carl Hanser Verlag, 2009). The chemistry, the hardening cycle and the tempering response for type 410 come from the heat treating reference information on printed page 200.