DRILLING TOOLS Wellhead Power Tongs,Elevator Slips,Wellhead Tools,Downhole Tools Rugao Yaou Import & Export Trade Co., Ltd , https://www.ntyaoumachinery.com
Common quality defects of bearing parts after heat treatment include: quenching microstructure overheating, underheating, quenching cracks, insufficient hardness, heat treatment deformation, surface decarburization, soft spots, etc.
Overheat
Overheating of the microstructure after quenching can be observed from the rough mouth of the bearing part. However, the exact microstructure must be observed to determine the degree of overheating. If coarse needle-shaped martensite appears in the quenched structure of GCr15 steel, it is quenched and superheated. The formation may be caused by excessive overheating of the quenching heating temperature or excessive heating and holding time; or it may be due to the serious banding of the original structure, forming a local martensite needle-like coarseness in the low carbon zone between the two zones. Local overheating caused. The retained austenite in the superheated structure increases, and the dimensional stability decreases. Due to the overheating of the quenched structure, the crystal of the steel is coarse, which leads to a decrease in the toughness of the part, a decrease in the impact resistance, and a decrease in the life of the bearing. Excessive heat can even cause quenching cracks.
2. Underheat
If the quenching temperature is low or the cooling is poor, a tortite structure exceeding the standard is produced in the microstructure, which is called an underheated structure, which lowers the hardness and sharply reduces the wear resistance, which affects the bearing life.
3. Quenching crack
The cracks formed by the internal stress during the quenching and cooling process of the bearing parts are called quenching cracks. The causes of such cracks are: due to excessive heating temperature of quenching or too rapid cooling, the microstructure stress when the thermal stress and metal mass volume change is greater than the fracture strength of the steel; the original defects of the working surface (such as surface micro cracks or scratches) Trace) or internal defects of steel (such as slag inclusion, severe non-metallic inclusions, white spots, shrinkage residuals, etc.) form stress concentration during quenching; severe surface decarburization and carbide segregation; insufficient tempering after quenching of parts Or not tempered in time; the cold punching stress caused by the previous process is too large, forging and folding, deep turning tool marks, sharp edges and corners of the oil groove. In short, the cause of the quenching crack may be one or more of the above factors, and the existence of internal stress is the main reason for the formation of quenching cracks. The quenching crack is deep and slender, the fracture is straight, and the fractured section has no oxidation color. It tends to be a longitudinal straight crack or an annular crack on the bearing ring; the shape on the bearing steel ball is S-shaped, T-shaped or ring-shaped. The microstructure characteristic of quenching cracks is that there is no decarburization on both sides of the crack, and the difference is obvious with forging cracks and material cracks.
4. Heat treatment deformation
When the bearing parts are heat treated, there are thermal stresses and tissue stresses. These internal stresses can overlap or partially cancel each other. It is complex and variable because it can follow heating temperature, heating speed, cooling method, cooling rate, and part shape. And the change in size changes, so heat treatment deformation is inevitable. Knowing and mastering the law of change can make the deformation of the bearing parts (such as the ellipse of the ferrule, the size of the ferrule, etc.) in a controllable range, which is conducive to the production. Of course, mechanical collisions during heat treatment can also deform the part, but this deformation can be reduced and avoided with improved handling.
5. Surface decarburization
During the heat treatment process of the bearing parts, if it is heated in an oxidizing medium, the surface will be oxidized to reduce the mass fraction of carbon on the surface of the part, resulting in surface decarburization. The depth of the surface decarburization layer exceeds the final processing allowance and the part is scrapped. Determining the depth of the surface decarburization layer The metallographic method and the microhardness method can be used in the metallographic examination. The surface layer microhardness distribution curve measurement method shall prevail and the arbitration criterion may be used.
6. Soft point
The phenomenon that the surface hardness of the bearing parts is insufficient due to insufficient heating, poor cooling, improper quenching operation, etc. is called quenching soft point. It can cause a serious drop in surface wear resistance and fatigue strength like surface decarburization.
Strength. With a robust and varied inventory, Drilling Tools is strongly positioned to support the oil and gas industry. With strategically located facilities, we have the capability to supply customers in a timely and efficient manner. Ultimately, our people are our greatest strength, as they allow us to deliver unsurpassed quality and service 24 hours a day, 7 days a week.
Innovation. Drilling Tools is on the cutting edge of the Oil and Gas marketplace. One example is the Drill-N-Ream® patented wellbore conditioning system. This system enables oil and gas operators to achieve the technical limits of today`s drilling challenges. Another innovative development is our low torque stabilizer offerings. These tools are geometrically configured to provide bottom hole assembly stability with minimal torque and drag to enable high rotational speeds and ease of slide drilling for trajectory control.
Performance. We know the importance our customers place on reliability. That's why when it comes to performance, the world's leading oil and gas operators and service companies are confident Drilling Tools will be there to provide reliable solutions to meet today's drilling challenges.
Common defects in heat treatment of bearing parts
Summary of Common Defects in Heat Treatment of Bearing Parts: Tightening Policy Continued Profits in Machinery Industry Enterprises High-speed Machining is the development trend of automobile mold manufacturing. Heavy-duty ball screw pair has recently developed a successful CNC milling machine. The basic machinery industry: technological progress drives the industry's continued Prosperity of the first imported CNC high-speed gear hobbing machine settled in Hangzhou rolling bearing oil selection of single-row angular contact ball bearings and double row angular contact ball bearings Japan to strengthen the development of China's machine tool and mold market, efficient thread cutters, what is the grinding machine? Laser control chip breaking Japan development KeyWord: self-lubricating bearing; new application of differential transmission type displacement sensor; digital interface circuit, valve selection, function and Main factors of piping system Virtual manufacturing technology Application defects in manufacturing industry Common handling of tissue surface parts Bearing overheating caused by stress bearing parts Heat treatment Common quality defects Quenching microstructure Superheated Quenching Crack hardness is not enough heat treatment Deformed surface decarburization 1. Hot rough bearing part quenched microstructure observed superheat superheat must determine the exact microstructure observed quenching occurs GCr acicular martensite hardened tissue overheating causes of possible quenching.