Production method of molybdenum and molybdenum alloy materials
Molybdenum and molybdenum alloy materials can be made by stamping, metal processing and welding. The surface of molybdenum alloy is processed with high precision. However, attention should be paid to the fact that molybdenum has high temperature strength but poor room temperature strength, and its toughness is not as good as that of carbon steel or brass. The higher ductile brittle transition temperature also indicates that molybdenum is prone to internal cracking.
Forming and metal pressure processing are common processing methods of molybdenum and molybdenum alloy, mainly including bending, stamping, punching, drawing and spinning. The machining effect is related to the surface state of the material, the size of the forming section and the deformation rate. In addition, molybdenum and molybdenum alloy have typical plastic anisotropy, that is, when bending molybdenum plate, the bending axis is perpendicular to the main rolling direction, the processing effect will be better. It is especially easy to produce plane cracks in the formed plates in stamping, punching and shearing billets, which are intergranular cracks spreading along the grain boundary plane during rolling. The preheating temperature of 4.0 ~ 6.0 mm MoCu alloy slab is above 1100 ℃; Mo and Mo alloy can be welded, that is, this method is usually used without excessive stress. The strength of the recrystallized zone of the solder joint and its surrounding matrix is very low, and the ductile brittle transition temperature is much higher than that of the non affected area around the solder joint. The concentrated deformation of the welding area and the three-dimensional stress caused by the limitation of the base metal can lead to brittle fracture. The general welding method of molybdenum and molybdenum alloy, that is, the welding seam and heat affected zone are small, so it is not easy to have problems. The results show that oxygen has a negative effect on welding and segregation at grain boundaries, thus reducing plasticity. Therefore, arc casting molybdenum alloy with higher carbon content is easier to weld than powder metallurgy molybdenum alloy. Similarly, carbide strengthened molybdenum alloy is easier to weld than pure molybdenum. Most molybdenum parts are welded in high purity inert gas chamber to minimize the adverse effect of oxygen. When welding materials containing volatile alloy components, bubbles (bubbles) will occur in the weld. Therefore, it is not easy to carry out welding processing by doping molybdenum alloy.
