24 July 2021 Precision Alloys
4j32 Precision Alloy Steel Bar
4J32 alloy, also known as super-tile (Super-Invar) alloy. In the temperature range of -60 ~ 80 ℃, the expansion coefficient is lower than that of 4J36 alloy, but the stability of low temperature is worse than that of 4J36 alloy.
The alloy is mainly used in the manufacture of precision instrumentation parts requiring high dimensional dimensions within the range of ambient temperature changes. Alloy 1.5 according to the provisions of the heat treatment system, and then by -60 ℃ cold speed 2h, should not appear martensite. However, when the alloy composition is not properly, at different temperatures of the austenite (γ) to the needle-like martensite (α) at room temperature or low temperature, the phase change is accompanied by the volume expansion effect.
The expansion coefficient of the alloy increases accordingly. The main factors that affect the stability of the alloy at low temperature are the chemical composition of the alloy. It can be seen from the Fe-Ni-Co ternary phase diagram that nickel is the main element of the stable γ phase. The high nickel content favors the stability of the γ phase.
Copper is also an important element of stable alloying. With the total deformation rate of the alloy increases, the organization tends to be more stable. Segregation of alloy components may also cause γ → α phase transformation in local regions. In addition, grain thickness will also promote γ → α phase transition.