Fasteners are a kind of general parts used for mechanical connection and fixation. The heat treatment process of fasteners is divided into two processes, heating and cooling, and reasonable control of the two processes can achieve the ideal heat treatment quality.
(1) Bolts, studs, screws, nuts and special-shaped non-standard parts mainly based on ML35 (32, 40), etc., due to the problem of material hardenability, such parts should be selected with a faster cooling rate during the heat treatment process Quenching medium, so as to meet the requirements of hardness, metallographic structure and mechanical properties of parts quenching.
① When the product specification is M4～M16, 3%～5% KR6480 polymer water-based quenching agent can be selected. If 35, 35S steel is selected, it can be relaxed to M18～M20.
② When the product specification is M10～M24, 8%～10% KR7280 water-soluble quenching agent can be selected.
③ When the product specification is larger than M24, 10%～15% KR7280 hydroquenching agent can be selected.
④ When the product is mainly 45 steel, KR6480 or KR7280 can be selected according to the size of the product.
(2) For bolts, studs, screws, nuts and special-shaped non-standard parts based on 35CrMo, 40Cr, 20MnTiB, etc., the quenching medium used is as follows.
① The products are mainly 35CrMo and 40Cr, and KR118 quick quenching oil or 5%-10% KR6480 polymer water-soluble quenching agent can be selected.
② The products are mainly 20MnTiB and 35VB, and quenching agents such as KR7280 or KR6480 can be selected.
(3) Shallow carburized self-tapping screws, pins, etc., based on low-carbon steel 10, 15, 20, 20Cr, 1018, 1022, 10B21, etc., can be selected as quenching agents such as KR6480 or KR118.
(4) Spring washers, retaining rings, etc. mainly made of 65Mn, 60Si2Mn, 70 steel, etc., can choose KR118 quick quenching oil.
(5) KR1188 or KR6480 can be selected for more product types and larger size spans, which can meet the quenching and carburizing quenching quality of all alloy steels and carbon steels of a certain size.