Question: 1045 Steel heat treatment creation
Question: 1045 Steel heat treatment creation
(OP)
sample of 1045 steel, air cooled from ~800C for 15sec then water quenched. HRC of 43. Temperatures not really known. Air cooled in cool room. water was 26C intially.
My thinking: Theoretically the microstructure might be anything that lies along the time:15sec vertical line of the 1045 TTT diagram, giving almost anything there but bainite.
I guess I am looking for someone who has experiance in this- who can give me a typical air cooling temp rate, or a typical composition
thanks!!
My thinking: Theoretically the microstructure might be anything that lies along the time:15sec vertical line of the 1045 TTT diagram, giving almost anything there but bainite.
I guess I am looking for someone who has experiance in this- who can give me a typical air cooling temp rate, or a typical composition
thanks!!





RE: Question: 1045 Steel heat treatment creation
RE: Question: 1045 Steel heat treatment creation
RE: Question: 1045 Steel heat treatment creation
In this case we already know the hardness, but not the size.
The 15 sec. delay in water quenching is of course more important as the size decreases.
RE: Question: 1045 Steel heat treatment creation
I can tell you a few more things about my processing of the specimen that will hopefully fill in a few more of the many missing pieces:
My specimen was about a 1.5" tall cylinder with a diameter of 3/4".
It was quenched in 4gal tap water (initial temp: 19.5C, final temp:26C). Afterwards, about 1/2" was sliced off (rather roughly) of one end after the heat treatment, the remaining expose circular face was polished .3u, then .1u cloth grit.
The HRC values were obtained on one of the faces. 43.8 was an average of many very similar values that were found running long the diameter. There was no significant change in the hardness between the inside and the edges.
Some of the grooves left from the blade were too deep to remove by polishing- they show up in parts of the SEM pictures.
The surface was chemically etched with 2% Nital and then the pictures were taken. (x200, x400)
RE: Question: 1045 Steel heat treatment creation
RE: Question: 1045 Steel heat treatment creation
RE: Question: 1045 Steel heat treatment creation
RE: Question: 1045 Steel heat treatment creation
All that being said, I am not sure what your question is. 800 C (1475 F) is marginally sufficient for austenitizing 1045. If anything happened during the air cool portion of the HT cycle, you should see free ferrite in the microstructure. In the AQ condition, I'd expect martensite and "a mix of higher temperature transformation products" meaning a mixture of bainite, fine pearlite, and possibly primary ferrite (depending on the actual composition, temperatures, and cooling rates.