Quenching Performance Analysis of Die Casting Die Steel
1. Mechanical properties of low carbon steel after tempering
When the tempering temperature is lower than 200 C, the strength and hardness hardly decrease, while the plasticity and toughness remain basically unchanged. This is because only carbon atoms are separated at this temperature without precipitation. Reasons for the retention of solid solution strengthening.
When tempering temperature exceeds 300 C, hardness decreases greatly and plasticity increases. This is due to the disappearance of solid solution strengthening, the aggregation and growth of carbides, the recovery and recrystallization of alpha phase. After tempering at low temperature, the comprehensive properties obtained are not superior to those of low carbon martensite.
2. High carbon steel is generally not quenched completely, so that the carbon content in austenite is about 0.5%.
High hardness is obtained after quenching and tempering at low temperature, and a large number of dispersed carbides are produced to improve wear resistance and refine austenite grains.
When the tempering temperature is higher than 300 C, the hardness and strength decrease obviously, the plasticity increases, and the impact toughness decreases to the lowest. This is because the sheet Theta carbides precipitate and grow adequately between martensite bands, which reduces impact toughness, while the alpha matrix improves plasticity, and the strength decreases due to the combined effect of recovery and recrystallization.
The hardness increases slightly when tempering temperature is lower than 200 C, which is due to aging hardening caused by precipitation of dispersed E (u) carbides.
Die casting die is one of the three main factors in the production of aluminium alloy die casting. The use of dies directly affects the life of dies, production efficiency, product quality and cost of die casting. For the die casting workshop, good maintenance of the die is a powerful guarantee to ensure the normal production of the die, is conducive to the stability of product quality, to a large extent reduces the intangible production costs, thereby improving production efficiency. In view of the problems encountered in the actual production, how to make the maintenance of the die better was discussed.
Baking Paint Die Casting Products
Firstly, the mould files should be set up and the preparatory work should be done well.
(1) When each die enters the factory, it is necessary to establish a complete set of usage records. This is an important basis to ensure future maintenance. Every project should be completed carefully and clearly, including daily production modules.
(2) As a die manager, the structural parts of each part of the die must be recorded in the die files after the die is imported into the factory. The vulnerable parts of the die should be listed according to the needs, and the minimum inventory of vulnerable parts should be established in advance, such as ejector rod and core, such as N, which delays production due to insufficient preparation. Because companies have so many experiences and lessons, it is necessary to prepare for them. If production is delayed due to unprepared spare parts, the cost of die-casting enterprises is very large, and the number of time, manpower, heat preservation furnace (or liquefied gas) is not small. The most important thing is the production delay. Delay in delivery will cause greater losses!
Technical Conditions for Pre-plating of Zinc Alloy Die Castings
There are two pre-plating processes for zinc alloy die castings:
(1) Mechanical polishing, chemical degreasing, electrodegreasing, cleaning, etching, cleaning and pre-plating.
(2) A mechanical polishing, degreasing, corrosion removal, cleaning, ash removal film, cleaning, pre-plating.
3.1 Mechanical Polishing
Polishing is to use parabola and polishing paste to slightly cut and polish the surface of parts, so as to make the surface of parts smooth and improve the surface finish. The linear speed of polishing wheels for zinc alloy die castings is generally 20-25 m/s. The parabolic wheels should be oiled in shifts, less oiled, first with red polishing paste, then with white polishing paste. Polishing is usually done by hand. Both hands exert force evenly, but not too much. In addition, the tangent point of the parabolic wheel should not stay in a certain position to prevent the smooth and compact surface of zinc alloy die casting from being thrown through, thus affecting the quality of electroplating.