Do you know where the wonderful journey of vanadium and cars started? Henry Ford I, founder of Ford, an American centuries-old store, happened to find that most of the parts were damaged seriously after the car crashed. Only one crankshaft was basically intact.
Later, curious people examined it and found that the vanadium contained in the crankshaft might be related to it. As a result, Ford has opened the history of vanadium microalloying for manufacturing key parts of Ford cars.
Vanadization of Automotive Parts
Before 1970s, tempered steels with complex manufacturing processes were always haunting the automotive parts industry: complex processes, long production cycle, high production costs, environmental pollution...
The emergence of vanadium brings hope to this predicament. In 1972, German Gerlach Company developed a vanadium microalloyed non-quenched and tempered steel 49MnVS3. The steel was forged to produce crankshaft for automobiles, successfully replacing medium carbon CK45 quenched and tempered steel.
This new technology breaks through the traditional understanding that only steel can be strengthened and toughened by quenching and tempering treatment. Without quenching and tempering treatment under hot rolling or hot forging conditions, mechanical properties can be guaranteed to match those of quenched and tempered steel. It is immediately attached great importance to by automotive manufacturing industry, thus revealing the extensive application sequence of vanadium microalloyed non-quenched steel in automotive industry and mechanical manufacturing industry. Curtain.
Compared with traditional quenched and tempered steels, why do microalloyed non-quenched and tempered steels get people's favor?
Eliminate conditioning and heat treatment, save heat treatment costs and reduce production costs;
Reducing environmental pollution caused by heat treatment, microalloyed non-quenched and tempered steel is known as "green steel".
Simplify production process, shorten production cycle and improve production efficiency.
Save straightening process, avoid waste products in straightening process, and improve product qualification rate;
Eliminating quenching and tempering process can reduce spare parts processing and increase material utilization rate by 5-10%.
Improve the cutting performance, improve the surface accuracy of parts and improve product quality;
The annealing process before cold drawing can be cancelled for cold work hardened non-quenched and tempered steel, the loss of annealing oxidation can be saved, and the utilization ratio of materials can be increased by 3-4%.
Vanadium-Vitamin in Steel
Why can vanadium play such a magical role?
First, vanadium precipitation strengthening
The solubility of vanadium in austenite is very high. At the conventional reheating temperature, vanadium can be fully dissolved in austenite. During the cooling process after forging, fine V (C, N) particles are precipitated, which significantly improves the strength of steel.
Second: Fine grain strengthening of vanadium
With the combination of nitrogen, vanadium carbide and nitride can precipitate in high temperature austenite, prevent austenite grain growth, increase phase transformation core, and increase the nucleation position of ferrite in grain, refine ferrite grain. Therefore, microalloying element vanadium is an important element for structure refinement.
Third: Nitrogen Fixation of Vanadium
Among all microalloying elements, only vanadium has the function of remoulding nitrogen. By forming vanadium nitride, the harmful element nitrogen in steel can be transformed into a favorable and cheap alloy element. At the same time, nitrogen can promote the precipitation of vanadium carbonitride, and transform most vanadium existing in the form of solid solution into vanadium precipitation, which can reduce the amount of vanadium alloying element and reduce the production cost of steel.
Therefore, in the relevant standards of microalloyed non-quenched and tempered steels, such as European standard EN10267-1998 and national standard GB/T15712-2016, almost all kinds of steels contain vanadium.
Rapid Development of Vanadium Microalloyed Non-quenched and Tempered Steel
The strong technical and economic advantages of vanadium microalloyed non-quenched and tempered steels mentioned above constantly promote the rapid application of vanadium microalloyed non-quenched and tempered steels in the automotive field. After more than 40 years of development, vanadium microalloyed non-quenched and tempered steel has been widely used in the manufacture of automobile crankshaft, connecting rod, steering knuckle, manipulator arm, front axle, rear axle, solar wheel, bearing seat, wheel hub, speed change fork, piston head, ball pin, etc. In addition, vanadium microalloyed non-quenched and tempered steel has been further applied in tractor connecting rod, crankshaft, gear, machine tool screw, flower, etc. Key shaft, spindle and other shaft parts; thread fasteners; sucker rods in pumping units and so on.
Our Gap
In the past ten years, China's automobile industry has made rapid progress. Ten years ago, in 2008, China's automobile production was only 9.345 million vehicles. By 2017, China's automobile production reached 29.11 million vehicles, accounting for more than 32% of the world's total output. It has been the world's largest automobile manufacturer for ten consecutive years. At the same time, China's own brand automobiles have also developed rapidly. In 2017, China's own brand passenger car market share reached 40%.
At present, although China is a big automobile producer, it is not a powerful automobile producer. The self-sufficiency rate of automobile parts is only 50%. There are still a large number of parts to be imported. At present, low-cost vanadium microalloyed non-quenched and tempered steels have been widely used in foreign automobile manufacturing industry. Compared with foreign countries, there is a big gap in the application quantity, application scope and technology development in China's automobile manufacturing industry. Especially for domestic automobiles with independent brands, the application proportion of vanadium microalloyed non-quenched and tempered steels is still very low. According to the estimation of China's automobile production, the potential usage of V microalloyed non-quenched and tempered steel should be in millions of tons every year, and the market prospects are broad.
In order to develop China's automotive industry better and faster, and vigorously increase the proportion of vanadium microalloyed non-quenched and tempered steels with excellent performance, omitting heat treatment and friendly environment, it is an inevitable trend for China's automotive parts industry to reduce costs, improve competitiveness and national energy saving and emission reduction.
