The microalloyed non quenched and tempered steel has the advantages of simplifying the production process, improving the material utilization rate, improving the quality of parts, and reducing energy consumption and manufacturing cost because it cancels the processes of quenching + high temperature tempering (quenching and tempering) of traditional carbon steel and alloy structural steel; At the same time, it has good social benefits such as energy saving, pollution reduction and green environmental protection.

The process flow comparison between manufacturing automobile connecting rod with non quenched and tempered steel and manufacturing connecting rod with original quenched and tempered steel is as follows:

Quenched and tempered steel: blanking – medium frequency heating – roll forging – pre forging – final forging – trimming – heap cooling – shot blasting – quenching and tempering – fine pressing – cold calibration – flaw detection – machining.

Non quenched and tempered steel: blanking – medium frequency heating – roll forging – pre forging – final forging – trimming – thermal calibration – controlled cooling – shot peening – fine pressing – flaw detection – machining.

It can be seen from the above comparison that the manufacturing of automobile connecting rod with non quenched and tempered steel not only saves the quenching and tempering treatment process after forging, but also saves the cold calibration process after heat treatment, so that the non quenched and tempered steel automobile connecting rod obviously has the following technical and economic characteristics and advantages.

1. The material consumption of heat treatment and related processes is saved, and the pollution is reduced. The elimination of quenching and tempering process can save the consumption of quenching medium (especially quenching oil) and the pollution caused by quenching and tempering. Non quenched and tempered steel shall be environmental friendly mechanical structural steel, known as “green steel”.
2. For the newly-built heat treatment workshop, some investment in heat treatment site, personnel and equipment can be saved; For the existing heat treatment workshop, the maintenance cost, material consumption and labor cost of some heat treatment equipment can be saved, and the heat treatment site can also be used for other purposes.
3. The cold calibration process is omitted. The original automobile connecting rod is easy to deform after heat treatment, so it must be straightened, and it is easy to produce waste products. After using the non quenched and tempered steel, because there is no heat treatment and no deformation, the cold straightening process is omitted, the deformation stress is avoided, the service life of the parts is improved, and the production cost is reduced.
4. The waste products generated in the heat treatment process are avoided. After the non quenched and tempered steel is used, the waste products caused by quenching cracking can be completely avoided because of no quenching treatment.
5. The non quenched and tempered steel is a material suitable for cracking automobile connecting rod. Compared with the traditional processing technology, the cracking technology is to replace the split processing with overall processing, change the semi-circular processing of the original automobile connecting rod body and automobile connecting rod cap into cracking, and round and finish the big head hole after assembling the bolts, eliminating the traditional processing procedures such as broaching and grinding of the joint surface of the automobile connecting rod body and automobile connecting rod cap, The bolt hole structure design and overall processing technology are simplified, and the processing accuracy requirements of bolt holes are reduced. Compared with traditional automobile connecting rod processing technology, cracking technology can reduce machining process by 60%, save equipment investment by 25%, reduce cutting tool cost by 35%, save energy by 40%, and reduce production cost by 15% ~ 20%. Its economic and social benefits are very significant.
6. Shorten production cycle and improve labor productivity. The use of non quenched and tempered steel automobile connecting rod not only saves the quenching and tempering process with a long production cycle, but also reduces the manufacturing process of automobile connecting rod, shortens the production cycle, and effectively improves the labor productivity. According to statistics, using non quenched and tempered steel to make parts can generally shorten the production cycle by about 15%.
7. It can reduce the number of employees and corresponding expenses, reduce costs, improve product competitiveness and improve material utilization. By using non quenched and tempered steel, the machining allowance of parts can be reduced, the size of materials used can be reduced, and the utilization rate of materials can be increased by 5% ~ 10%.

Microalloyed non quenched and tempered steel is strengthened by adding trace V, Ti, Nb and other elements into the steel, and then precipitation of carbides or carbonitrides in ferrite and pearlite after forging or rolling cooling. It does not need quenching and tempering, which can reduce heat treatment procedures and equipment, avoid waste products caused by heat treatment deformation and quenching cracks, and reduce consumption and production costs.

Automobile connecting rod is made of non quenched and tempered steel. At the current price, although the non quenched and tempered steel used for manufacturing automobile connecting rod is about 400 yuan per ton more expensive than the original carbon 45 steel, the non quenched and tempered steel does not need heat treatment, and the direct heat treatment cost can be saved about 800 yuan per ton; Because the non quenched and tempered steel is easy to process, it can save about 800 yuan per ton of cutting tools and electricity; In addition, other indirect saved costs, such as labor cost and the cost saved by shortening the production cycle and reducing the scrap rate, are equivalent to about 600 yuan per ton of automobile connecting rod. According to rough accounting, the production of diesel engine connecting rod with non quenched and tempered steel can save 8-11 yuan per piece.

China has abundant V, Ti and Nb resources, which can fully meet the development needs of domestic microalloyed non quenched and tempered steel. With the further development and wide application of non quenched and tempered steel, steel mills will produce higher quality and lower price non quenched and tempered steel. Therefore, the development of non quenched and tempered steel automobile connecting rod has considerable economic benefits. Microalloyed non quenched and tempered steel automobile connecting rod has excellent technical and economic characteristics. The development of non quenched and tempered steel automobile connecting rod can not only reduce the production cost of automobile connecting rod, but also improve the labor productivity and market competitiveness of products, so as to lay a foundation for the expanded use of non quenched and tempered steel.

Of course, when the metallurgical plant produces non quenched and tempered steel, it needs to add microalloy additives, which increases the difficulty of process control, and will increase the price of rolled products. In machinery manufacturing plants, die losses will be increased due to relatively low requirements for hot forging temperature and increased resistance to thermal deformation, but the total manufacturing cost will be significantly reduced. For example, the Volkswagen automobile factory in Europe uses 27mnvs6 to manufacture automobile connecting rods, reducing the total cost by 10%. The excellent technical and economic characteristics of microalloyed non quenched and tempered steel will have great attraction for relevant enterprises eager to survive in the market competition.