How to detect raw materials of stainless steel rods for petrochemical industry?

The machining department of a petrochemical unit needs to conduct ultrasonic non-destructive testing of semi-finished stainless steel rods when producing pressure components such as pressure-soluble bomb casings and micro-reactor joints. In the past, the flaw detection method was: cut the stainless steel bar provided by the supplier into appropriate small sections, rough-turn the outer circle, and flatten both ends; after passing the visual inspection, use a straight probe to detect flaw from the two ends of the cylinder using the flat contact method. Curved surfaces are tested using circumferential and longitudinal water immersion methods with straight probes. In this way, the problem of the limitation of the length of the water-flooding flaw detection tank on the length of the inspected material is solved. However, this detection method becomes destructive testing for stainless steel rod raw materials. After defects are found during inspection, it is difficult to return or replace them, which wastes materials, increases processing costs, and causes losses to the unit. On the other hand, the results of inspection by this method are: flaw detection is carried out from both end faces of the cylinder using the straight probe contact method, and few defects are found: semi-finished products that have undergone "comprehensive" flaw detection, the finished product is still normal during the pressure test and use. Individual longitudinal cracking occurs.

The wire rod petrochemical machinery processing department generally only needs to use the oblique probe contact method to conduct circumferential flaw detection on the stainless steel rod raw material along the circular surface in both clockwise and counterclockwise directions, so that defects buried on the surface and near the surface of the raw material can be found. Ultrasonic non-destructive testing is light and flexible, can quickly find defects, accurately locate defects, and can be used for on-site flaw detection. On simple tooling, the entire length or section of the raw material can be inspected for flaw detection to roughly judge its overall quality. If problems are found, materials can be returned and replaced in a timely manner to achieve selective purchase of materials, which can greatly reduce production costs and reduce material waste. .

With the rapid development of my country's automobile industry, the demand for free-cutting steel for automobiles is increasing. The use of free-cutting steel in automobiles accounts for about 2.1% of the weight of the entire vehicle, second only to carbon steel (accounting for 5.8%), alloy steel (accounting for 3.7%), accounting for the third place in the steel materials used in automobiles. At present, the annual demand for free-cutting steel for automobiles in my country is about 100,000 tons (excluding steel used in the agricultural machinery industry and agricultural machinery such as tractors), but there is a big gap compared with Japan's annual consumption of 1 million tons. It can be seen that my country's free-cutting steel The development potential is great.

Free-cutting steel is mainly used to manufacture automobile parts, such as crankshafts, connecting rods, struts, steering bars, running parts, washers, flanges, gear brakes, shafts, racks, spark plugs, etc.