Effect of Tempering Temperature on Microstructure and Corrosion Resistance of Plastic Mould Steel S136 SUP

Since the 21st century, the development of automotive and home appliance industries has greatly contributed to the prosperity of the plastics industry, which has led to an increasing demand for molding molds. In the production process, the molds will be impacted, worn and corroded, especially in the production of plastic products made of PVC, fluoroplastics and flame retardant ABS, etc. The molds will be corroded by the corrosive gases generated such as hydrogen chloride, hydrogen fluoride and sulfur dioxide, which requires plastic molds to have a certain degree of corrosion resistance while ensuring strong toughness.S136 SUP is a modified martensitic stainless steel based on S136 from ASSAB, Sweden, which has fine-tuned the content ratio of some elements to ensure a certain strength and high toughness at the same time. The chemical composition, heat treatment and microstructure of the steel have a certain influence on its corrosion resistance, and the tempering temperature of the heat treatment has a greater influence on the corrosion resistance of martensitic stainless steel. Therefore, in this paper, the microstructure and corrosion resistance of S136 SUP at different tempering temperatures are explored and studied.

Comparison of microstructure and mechanical properties of plastic mould steel for physical application

In this paper, plastic mold steel S136 and S136 SUP were studied for microstructural observation and mechanical properties through metallographic, SEM, EDS, XRD, hardness test and impact test. The results showed that after the same heat treatment, the martensite structure of S136 SUP was denser, the carbides were more uniform and finer, and the hardness was slightly lower but the toughness was greatly increased compared with that of S136. the residual austenite content of S136 and S136 SUP were 2.46% and 10%, respectively, and the heat treatment hardness was 50.1 HRC and 49.1 HRC, respectively. The impact toughness was 90.6 J and 299.1 J.

Study on Machinability of Pre-Hardened Plastic Mould Steel

The relationship between machinability and microstructure of plastic mould steel is still not clear enough, despite the application of plastic mould steel is more and more wide. In this study, two typical plastic mould steels, namely, 718 (DIN 1.2738) and SDP1 steel with the same hardness are chosen to investigate turning force, tool wear and milling force by experimental test. Combining with the turning and milling test, discussions about cutting force and the relationship between machinability and microstructure are made. And it’s found that the micro-uniformity has a great effect on the machinability of plastic mould steel.

Development of Domestic Prehardened Plastic Mould Steel

The classification, properties of the domestic prehardened plastic mould steel are reviewed, the composition design and heat treatment process improvement in the chinese prehardened plastic mould steel are commented, its development direction is pointed out. Quenched and tempered prehardened steel has been developed and upgraded based on foreign steels, while non-quenched and tempered prehardened was invented by ourselves, and has been researching and developing because of its good cost performance ratio.