New Engineering Materials for Industrial High Pressure Valves
When choosing the material of flow passage parts of Industrial High Pressure Valves, the different flow velocities (maximum operating pressure) and weightlessness should be taken into account. At high pressure (over 400 MPa), materials with high hardness and good red hardness, such as tool steel or cemented carbide, are selected. At low pressure (100-400 MPa), the material is required to have good plasticity and willfulness, as well as high hardness. For example, the ultra-high pressure needle valve of HIP Company in USA uses austenitic 316 stainless steel with working pressure of 690 MPa and body precipitation hardening stainless steel 17-4PH with working pressure of 1034 MPa. Overseas, stainless steel and tool steel are used for parts, discs and seat to withstand cavitation erosion, while chromium-aluminium steel and stainless steel are used for seat base. With the successful development of industrial ceramic technology, ceramic material valves have also appeared. Ceramic materials have high erosion resistance at low angle of attack, but due to the reduction of needle taper, the strength at the end of the needle decreases, and the reaction force between needle and seat decreases, which affects the reliability of the seal. Therefore, when choosing ceramic material to make valve needle, not only its taper but also its strength should be considered.