I buy a spring made of 1.2mm steel wire from a hardware store that needs quenching
It may be that the wire itself is not made of spring.The main performance requirements of spring steel are high strength and high yield limit and fatigue limit, so spring steel has higher carbon content. However, the hardenability of carbon steels is poor, so alloy steels must be used for springs with larger cross sections. The major alloying elements in alloy spring steels are silicon and manganese. They can increase hardenability and yield strength of steel.Carbon steel is used for spring with smaller diameter, and the process is mostly cold drawing, such as 65#, 75#, 85#.The diameter is a little big, and the spring produced by thermoforming process adopts 60Si2Mn, such as automobile leaf spring and buffer spring of railway vehicle.For high stress important spring can use 50CrV, commonly used in advanced sedan leaf spring, engine valve spring, etc..Other spring steel materials include: 65Mn, 50CrMn, 30W4Cr2V, etc..1.2mm diameter is not fine, so it is not hardened, it is too hard to break.
First of all, you don't know whether the material is suitable for springs.Gas torch burning red spring, water or oil? The quenching temperature is not too good. It's too difficult to control: it can't be just right. Besides, tempering is necessary after quenching. Without tempering, of course, very brittle (hardened case), to the temperature above 400 degrees insulation for a period of time.If you're patient, experiment slowly, I hope. But if you're discouraged, it's hard to succeed.
The quenching temperature of the spring depends on the critical temperature of the spring material. After quenching, there should be no free ferrite and cementite in the metallographic structure of the spring material, so as not to lead to uneven deformation or fatigue strength. When quenching, the oxidation and decarburization shall be prevented as much as possible.
In general, hot bending spring coil spiral spring and disc spring of hot stamping, preferably in hot forming and quenching by the heat immediately. In this way, the heating and the decarburization degree of the spring can be omitted, and the surface quality of the spring can be improved both economically and at the same time.
Spring: Spring quenching hardening is the steel is heated to the critical temperature of Ac, or Ac: the above heat preservation time, the austenite with greater than the critical cooling rate of rapid cooling, so as to obtain the heat treatment method of martensite.
