Sustainability has become a very important issue in the context of global warming, which is the biggest problem of our age. Sustainable manufacturing practices are one of the significant environmental initiatives taken by manufacturing industries to preserve the environment and improve the quality of human life while performing manufacturing activities. In terms of sustainable manufacturing, materials must be processed at the most optimum cutting parameters. For this reason, cutting tool selection and optimization of machining parameters are made. In addition, the correct selection of cutting fluids used as coolants has also become important. Today, the Cryogenic Cooling method and the Minimum Lubrication Amount (MQL) cooling method are used as an alternative to conventional cooling fluids. Especially in the context of green manufacturing, the MQL technique has become prominent in recent years and its usage is becoming widespread. Among the main features of the MQL technique are that it reduces the cutting zone temperature and the amount of lubrication needed to reduce friction in the cutting zone. In the cryogenic cooling method, liquid nitrogen is used as a cooling liquid to reduce the temperature in the cutting zone.

In addition to heat treatment, surface hardening processes such as cementation, nitruration, carbonitruration, and boring are performed to improve the mechanical properties of tool steels. In recent years, the cryogenic process, which is a complementary process to heat treatment, has emerged to improve the mechanical properties of tool steels. The cryogenic process is known as the process of keeping materials in a liquid or gas environment in nitrogen up to -196 °C. This method is of great importance in terms of sustainable manufacturing since it does not have any negative impact on the environment. It has been subject to a lot of research effort due to its superior properties such as increased hardness, high wear, fatigue and impact resistance, homogeneous microstructure, low residual austenite ratio, low residual stress, high tensile strength, and high dimensional accuracy. Experimentally, it is necessary to carry out considerable processing to determine the optimum conditions, which is undesirable in terms of both time and cost. For this reason, different optimization techniques such as the Taguchi method, artificial neural networks, response surface methodology, fuzzy logic, and genetic algorithms can be applied to experimental results in order to determine optimal processing conditions with fewer experiments.

In this Special Issue, we aim to publish articles on the improvement of the mechanical properties of high-strength steel, especially sustainable manufacturing, cryogenic machining and cryogenic treatment applications, minimum quantity lubrication technique, heat treatment applications, surface integrity, and optimization techniques. Likewise, we hope to attract review articles describing the current state of the technology.

Potential topics include but are not limited to the following:

• Sustainable and green manufacturing
• Sustainable optimization
• High-strength materials (tool steels, super alloys, composites, etc.)
• Mechanical behaviours of materials: tensile, fatigue, residual stress, and other mechanical characteristics
• Cryogenic machining
• Cryogenic treatment
• Minimum quantity lubrication (MQL)
• Optimization techniques (machine learning, Taguchi analyses, response surface method, regression, etc.)
• Heat treatment, coatings, boring, etc.
• Artificial Neural Networks (ANN) and Finite Element Modelling (FEM)
• Additive manufacturing
• Surface integrity