Heat Treating Common Steels Temperature and Quenching Medium Chart

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Heat Treating Common Steels Temperature and Quenching Medium Chart

Heat Treating Common Steels Temperature and Quenching Medium Chart

Quenching Media: Quenching solutions act only through their ability to cool the steel. They have no beneficial chemical action on the quenched steel and in themselves impart no unusual properties. Most requirements for quenching media are met satisfactorily by water or aqueous solutions of inorganic salts, such as table salt or caustic soda, or by some type of oil. The rate of cooling is relatively rapid during quenching in brine, somewhat less rapid in water, and slow in oil.

Tempering: Tempering reduces the brittleness imparted by hardening and produces definite physical properties within the steel. Tempering always follows, never precedes, the hardening operation. In addition to reducing brittleness, tempering softens the steel. Tempering is always conducted at temperatures below the low critical point of the steel. In this respect, tempering differs from annealing, normalizing, or hardening, all of which require temperatures above the upper critical point.

Annealing: Annealing of steel produces a fine-grained, soft, ductile metal without internal stresses or strains. In the annealed state, steel has its lowest strength. In general, annealing is the opposite of hardening. Heating the metal to just above the upper critical point, soaking at that temperature, and cooling very slowly in the furnace accomplishes annealing of steel.

Normalizing: The normalizing of steel removes the internal stresses set up by heat treating, welding, casting, forming, or machining. Stress, if not controlled, leads to failure. Because of the better physical properties, steels are often used in the normalized state, but seldom, if ever, in the annealed state. One of the most important uses of normalizing is in welded parts. Welding causes strains to be set up in the adjacent material. In addition, the weld itself is a cast structure as opposed to the wrought structure of the rest of the material. These two types of structures have different grain sizes, and to refine the grain as well as to relieve the internal stresses, all welded parts should be normalized after fabrication.

Heat Treating Steels Temperature and Quenching Medium Table

Steel Number	Temperatures			Quenching Medium (n)
Steel Number	Normalizing Air Cool (°F)	Annealing (°F)	Hardening (°F)	Quenching Medium (n)
1020	1,650–1,750	1,600–1,700	1,575–1,675	Water
1022 (x1020)	1,650–1,750	1,600–1,700	1,575–1,675	Water
1025	1,600–1,700	1,575–1,650	1,575–1,675	Water
1035	1,575–1,650	1,575–1,625	1,525–1,600	Water
1045	1,550–1,600	1,550–1,600	1,475–1,550	Oil or water
1095	1,475–1,550	1,450–1,500	1,425–1,500	Oil
2330	1,475–1,525	1,425–1,475	1,450–1,500	Oil or water
3135	1,600–1,650	1,500–1,550	1,475–1,525	Oil
3140	1,600–1,650	1,500–1,550	1,475–1,525	Oil
4037	1,600	1,525–1,575	1,525–1,575	Oil or water
4130 (x4130)	1,600–1,700	1,525–1,575	1,525–1,625	Oil (c)
4140	1,600–1,650	1,525–1,575	1,525–1,575	Oil
4150	1,550–1,600	1,475–1,525	1,550–1,550	Oil
4340 (x4340)	1,550–1,625	1,525–1,575	1,475–1,550	Oil
4640	1,675–1,700	1,525–1,575	1,500–1,550	Oil
6135	1,600–1,700	1,550–1,600	1,575–1,625	Oil
6150	1,600–1,650	1,525–1,575	1,550–1,625	Oil
6195	1,600–1,650	1,525–1,575	1,500–1,550	Oil
NE8620	—	—	1,525–1,575	Oil
NE8630	1,650	1,525–1,575	1,525–1,575	Oil
NE8735	1,650	1,525–1,575	1,525–1,575	Oil
NE8740	1,625	1,500–1,550	1,500–1,550	Oil
30905	—	(g)(h)	(i)	—
51210	1,525–1,575	1,525–1,575	1,775–1,825 (j)	Oil
51335	—	1,525–1,575	1,775–1,850	Oil
52100	1,625–1,700	1,400–1,450	1,525–1,550	Oil
Corrosion resisting (16-2)(1)	—	—	—	—
Silicon chromium (for springs)	—	—	1,700–1,725	Oil

Steel Number	Tempering (drawing) Temperature for Tensile Strength (psi)
Steel Number	100,000 (°F)	125,000 (°F)	150,000 (°F)	180,000 (°F)	200,000 (°F)
1020	—	—	—	—	—
1022 (x1020)	—	—	—	—	—
1025	(a)	—	—	—	—
1035	875	—	—	—	—
1045	1,150	—	—	(n)	—
1095	(b)	—	1,100	850	750
2330	1,100	950	800	—	—
3135	1,250	1,050	900	750	650
3140	1,325	1,075	925	775	700
4037	1,225	1,100	975	—	—
4130 (x4130)	(d)	1,050	900	700	575
4140	1,350	1,100	1,025	825	675
4150	—	1,275	1,175	1,050	950
4340 (x4340)	—	1,200	1,050	950	850
4640	—	1,200	1,050	750	625
6135	1,300	1,075	925	800	750
6150	(d)(e)	1,200	1,000	900	800
6195	(f )	—	—	—	—
NE8620	—	1,000	—	—	—
NE8630	—	1,125	975	775	675
NE8735	—	1,175	1,025	875	775
NE8740	—	1,200	1,075	925	850
30905	—	—	—	—	—
51210	1,200	1,100	(k)	750	—
51335	—	—	—	—	—
52100	(f )	—	—	—	—
Corrosion resisting (16-2)(1)	(m)	—	—	—	—
Silicon chromium (for springs)	—	—	—	—	—

Notes:

(a) Draw at 1,150 °F for tensile strength of 70,000 psi.
(b) For spring temper draw at 800–900 °F. Rockwell hardness C-40–45.
(c) Bars or forgings may be quenched in water from 1,500–1,600 °F.
(d) Air cooling from the normalizing temperature produces a tensile strength of approximately 90,000 psi.
(e) For spring temper draw at 850–950 °F. Rockwell hardness C-40–45.
(f ) Draw at 350–450 °F to remove quenching strains. Rockwell hardness C-60–65.
(g) Anneal at 1,600–1,700 °F to remove residual stresses due to welding or cold work. May be applied only to steel containing titanium or columbium.
(h) Anneal at 1,900–2,100 °F to produce maximum softness and corrosion resistance. Cool in air or quench in water.
(i) Harden by cold work only.
(j) Lower side of range for sheet 0.06 inch and under. Middle of range for sheet and wire 0.125 inch. Upper side of range for forgings.
(k) Not recommended for intermediate tensile strengths because of low impact.
(l) AN-QQ-S-770—It is recommended that, prior to tempering, corrosion-resisting (16 Cr-2 Ni) steel be quenched in oil from a temperature of 1,875–1,900 °F, after a soaking period of 30 minutes at this temperature. To obtain a tensile strength at 115,000 psi, the tempering temperature should be approximately 525 °F. A holding time at these temperatures of about 2 hours is recommended. Tempering temperatures between 700 °F and 1,100 °F is not approved.
(m) Draw at approximately 800 °F and cool in air for Rockwell hardness of C-50.
(n) Water used for quenching shall be within the temperature range of 80–150 °F.

Figure 1 Temperature chart indicating conversion of Centigrade to Fahrenheit or vice versa, color temperature scale for hardening temperature range, and tempering temperature range.

Reference:

Federal Aviation Administration
Aviation Maintenance Technician Handbook,
FAA-H-8983-30A
2018